Glenn's Computer Museumurn:uuid:7d108532-31e2-3b01-a843-002544115e922015-03-07T00:00:00ZG. Glenn HenryA collection of old IBM and military computers.AMF 662/D Computer2015-03-07T00:00:00ZG. Glenn Henryurn:uuid:7beb88cc-5e30-35db-837b-fd8cccc1505a<h3>AMF 662/D Computer</h3>
Sperry/Ford Mark-6 Fire Control Computer2014-09-11T00:00:00ZG. Glenn Henryurn:uuid:e8b8d08c-992d-3682-9383-11b7cadb8059<h3>Sperry/Ford Mark-6 Fire Control Computer</h3>
<p>World War II gave rise to some amazing electromechanical computers used by the military.
The most impressive was the Navy's <a href="http://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer">Mark I and Mark 1A fire control computers</a>.
used on battleships.
A great reference to this device and many similar electromechanical fire control devices
can be found at <a href="http://www.hnsa.org/doc/#guns"">this site</a>.
Most of the complex fire control equipment, including the Mark I, was designed by the Ford Instrument Company (not associated with Ford Motors).
Here is a great paper on <a href="http://web.mit.edu/STS.035/www/PDFs/Newell.pdf">Ford-designed mechanical analog computers</a>.</p>
<p>As far as I know, there are no intact versions of these large WWII devices outside of historic ships,
although we have a <a href="../mark1/">couple of pieces</a> of a Mark I in our museum.
However, we do have a complete, but smaller, WWII fire control computer designed by the Ford Instrument company,
and, interestingly, manufactured by IBM.
It is mentioned in the above referenced paper, we find "Ford's answer to the merchant ship problem was the Computer Mark 6...
Although only about the size of a large wheel of cheese,
it ingeniously contained a simplified capability for solving the surface fire control problem."</p>
<p>Figures 1 and 2 shows our "large wheel of cheese" sized Mark 6 mod 16 computer.
Figure 3 shows a close up (hard to read, I recommend the largest size photo)
of its label showing its pedigreed (Ford and IBM) along with a May 1942 date.
The label notes that it is for a <a href="http://en.wikipedia.org/wiki/3%E2%80%B3/50_caliber_gun">3" 50-caliber gun</a> shooting a 13 lb. AA projectile.
Other WWII naval fire control computers were electrically powered;
the Mark 6, however, is manually powered using a spring motor, wound by hand with the knob on the lower left of Figure 2.</p>
<p>I can find only three references to this device after significant searching: (1) the above mentioned paper on Ford computers,
(2) Figure 9, a picture of the device in a <a href="http://www.ussslater.org/tour/decks/flyingbr/gun-dir-hut/director.html">restored WWII destroyer escort</a>,
and (3) Figure 16, a picture in a navy manual describing <a href="http://www.eugeneleeslover.com/USNAVY/CHAPTER-20-F.html">fire control equipment in a 16" gun turret</a>.</p>
<p>(Both these sites are great if you are interested in navy ships, especially from WWII.)</p>
<p>There are several mysteries here. First, even though the Ford computer reference above talks about <a href="http://en.wikipedia.org/wiki/Defensively_equipped_merchant_ship">defensively equipped merchant ships</a>,
Figure 6 shows that someone wrote "off ship Arkansa's" [sic] on our device.
That seems to be a reference to an old WWII battleship,
<a href="http://en.wikipedia.org/wiki/USS_Arkansas_%28BB-33%29">the USS Arkansas, BB-33</a>,
which, in fact, did have 3"/50 guns.
In addition, we have the Figure 9 picture of our computer mounted in a destroyer escort.
Since the 3"/50 gun was used on almost every US ship in WWII,
it is likely that the Mark 6 computer was used on many ships.
And, we have what must be a variant model associated with the main guns of a a battleship (Figure 9).
The second mystery is the fact that the label mentions an "AA projectile", yet
the details of the Mark 6 operation seem to be suited to ship-to-ship firing.
Also, the above Ford reference talks about "<em>surface</em> fire control" for the Mark 6.</p>
<p>Finally after a lot of physical effort (the bolts were corroded), we have removed its case exposing its innards as shown in Figures 10-15.
Figure 11 is a close-up of part of a mechanical multiplier that lies under the ship and target inputs.
The spring that powers its calculations is a large cylinder shown in Figures 13 and 14.
Near the bottom left of Figure 13 is the governor that tries to produce a constant speed output
as the spring unwinds.
Figure 15 is the back of the device showing the bearings for some of the mechanisms.</p>
<p>It is obvious from the dirt and marring on the face that this device was used.
The insides, however, are pristine!
And, the only lubrication is on the spring pedestal (the dark blob on the bottom left of Figure 15).</p>
IBM System/322014-03-30T00:00:00ZG. Glenn Henryurn:uuid:1658c2c1-08f8-3eec-93d9-49ae5f444cd2<h3>The IBM System/32: The Second IBM Personal Computer</h3>
<p>Announced in early 1975, the <a href="http://www-03.ibm.com/ibm/history/exhibits/rochester/rochester_4017.html">IBM System/32</a>
was the lowest cost IBM offering (at the time) and became very popular.</p>
<p>It was a small single-user business-oriented computer that was less expensive than the System/3 Model 6 (some models leased for less than $1,000 per month.
The System/32 was designed for business applications (e.g., billing, inventory control, accounts receivable, sales analysis, etc.) written in RPG.</p>
<p>The system was a single desk-sized unit comprising a processor, fixed-disk storage, a data diskette, a printer, and an operator console
with a small visual display screen.
The System'32's tiny display contained six lines of 40 characters each.
Solid-state main storage was available in sizes from 16K to 32K bytes.
A emovable contained around 262 KB, and the fixed disk options were approximately 5 or 9MB.
Two communication options were available (BSCA and SDLC) supporting data rates up to 7200 bps.</p>
<p>Figure 1 shows the complete System/32 (the weird photo angle is to mask a huge amount of junk in the room).
Figure 2 shows the operator station with the small display on the left and the printer behind the keyboard,
which is shown in more detail in Figure 3.
Figure 5 shows the hidden CE panel (in front of which I spent many nights, see below).
Swinging the logic gate out, we see in Figure 5 the giant disk drive.
Figure 6 and 7 show the front and back of the logic gate.
This small amount is the entire logic in the system (other than the CRT control logic and without the optional communications feature).
Figure 8 shows the back of the unit with the vertically mounted CRT in a shield to the left of the disk drive.
The motor for the diskette reader is alos seen below the CRT shield.</p>
<p>From an application viewpoint, the System/32 had the same instruction set as the System/3 models and the system software (SCP) was very similar to that of the System/3 Model 6's. Similarly, the primary application language was RPG.
Due to its small business orientation and low cost, the System/32 was very successful:
according to the IBM link, it became the most installed IBM computer of the 1970's.</p>
<p>Even though the System/32 appeared to software to have the System/3 instruction set,
internally the processor did not directly execute System/3 instructions.
To minimize cost, the I/O devices were very "dumb" and the processor (called the Control Storage Processor, or CSP)
was optimized for low-level control of the I/O devices.
The code executing in the CSP (called microcode) was contained in a writable control storage
and included an emulator of the System/3 instruction architecture.</p>
<p>Microcode for the System/32 was much simpler than the typical "horizontal" microcode as implemented on other IBM processors.
The System/32 processor had what we would later call a RISC architecture.
Instructions were 16-bits wide and addresses were 16-bits wide.
The microcode control storage was 4K 16-bit words (an extension of another 4K was available and contained emulation of floating-point arithmetic).
Four usable interrupt levels each had eight 16-bit general purpose registers.
All logical and arithmetic instructions were register-to-register operations.
Main memory was accessed only by load and store instructions.
There were condition flags for branching and only about 19 basic instructions.
Of course, there was no pipelining, no caches, no branch prediction, or other performance features like are common on modern processors.</p>
<p>A CSP instruction executed in, on average, five to seven 200ns clock pulses.
That is, a CSP microcode instruction instruction executed in about the same time as the 1.5us processing of a byte in the memory-to-memory architecture of the System/3.
Since emulation of a System/3 architecture instruction tool many microcode cycles, emulation of System/3 was very slow.
This lead to the innovation of moving some of the SCP into microcode (discussed more below).</p>
<h4>Sidebar: My Personal History With the IBM System/32</h4>
<p>In 1970, I finished my work on system software for the <a href="../s3m6/">IBM System/3 Model 6</a>.
I then worked on the architecture of another proposed small computer, which was killed and the key personnel asked to move to Rochester MN.
I was offered the job of the second line manager developing the operating system (the System Control Program, in IBM terminology)
for a new small computer system (which ultimately became the System/32).
So, in 9/71, I moved to Rochester (getting married to an IBM programmer on the way).</p>
<p>As well as being the manager of the system software development,
I proposed and personally coded microcode that implemented some of the disk management functions of the operating system in microcode.
While this seems obvious now, at the time I believe this was the first time this was done in IBM (moving SCP functions into microcode).
I vividly remember watching the 1972 Olympics at home nights while also translating the System/3 SCP disk management code in microcode.
There was no simulator of the CSP; the only way to debug code was on the hardware.
Machine time was hard to get since there were few models available and the engineers were busy working on them.
Thus, I mainly found time to use the hardware at night.
I remember long nights sitting in front of a very early hardware model and debugging my code using the control panel shown in Figure 4 (the only debug mechanism available).
Due to the developing nature of the hardware, I also found a few bugs in the hardware.</p>
<h4>The Museum's System/32</h4>
<p>The museum acquired the System/32 from its original owner in a small ranching and farming town in Oregon.
This information came from its only owner before the museum acquired it:</p>
<p>"I bought it new in the 70's for a farm machinery business to do bookkeeping and some inventory control.
There were no bookkeeping software packages tailored for the 32 at that time,
so the IBM sales folks found me a system 3 package and a programmer to modify it to run on the 32.
My training to this point was a degree in engineering using a slide rule.
I worked with the programmer and the wonderful instruction manuals and learned RPGII
and went on to write many programs for the 32 and my business."</p>
IBM System/3 Model 62013-08-30T00:00:00ZG. Glenn Henryurn:uuid:ba04f870-b370-3db5-85bf-bb92a02c49d0<h3>The IBM System/3 Model 6: The "Real" First IBM Personal Computer</h3>
<p>The <a href="http://en.wikipedia.org/wiki/IBM_System/3">IBM System/3 family</a> was a very successful line of small business-oriented computers in the 1970's.
The first member, the Model 10, shipped in mid-1969 and was a card-based batch-oriented system intended to replace unit-record
(punched card) commercial applications: billing, inventory control, accounts receivable, sales analysis, payroll, etc.
The System/3 applications were written in RPG, a non-procedural language originally based on the data-flow of IBM card-based accounting machines.
Of particular interest, the Model 10 introduced a new format of punched card along with I/O devices for it.
This card was much smaller than the standard IBM card but could contain more data: 96 columns vs. 80 columns.</p>
<p>Figures 1 and 2 show our console from the card-oriented IBM System/3 Model 10.</p>
<p>The System/3 Model 6,shipped in late 1970, was the second model introduced.
As opposed to the card-based batch-oriented Model 10, the System/3 Model 6 was designed for interactive usage, both for business applications, but also for engineering and scientific applications.
It had no attached card equipment, but rather had a good keyboard and an (optional) CRT display.
The business applications used the same general operating system and RPG language,
but there was a new interactive BASIC-language operating system for engineering and scientific applications.</p>
<p>Figure 3, from an IBM ad, shows a person using the System/3 Model 6 with its BASIC software package.
Figures 4 etc. show the museum's Model 6 (we do not have the optional CRT display).</p>
<h4>Sidebar: My Personal History With the IBM System/3 Model 6</h4>
<p>In 1968 I was working at IBM San Jose on the design of a follow-on to the IBM 1130,
a small engineering and scientific computer.
Late in the year, our project was redirected by upper management
to use another IBM processor that was being developed in Rochester: the IBM System/3 processor.
This was probably the worst architecture ever imagined for engineering and scientific computing:</p>
<ul>
<li>No floating-point instructions</li>
<li>No multiply or divide instructions</li>
<li>No shift instructions</li>
<li>No registers (other than 2 index registers)</li>
<li>(All operations were memory-to-memory)</li>
<li>Only 16-bit addresses, no virtual memory hardware</li>
<li>etc.</li>
</ul>
<p>I was redirected as well--to the newly forming Boca Raton development laboratory.
I arrived in Boca in early 1969 and became the manager of one of two departments developing the
<em>IBM System/3 Model 6 BASIC</em> program.
I managed the operating system underlying the BASIC interpreter.
My department implemented a 64KB virtual memory (in software, there was no address translation hardware),
the math library, the I/O subsystem, a powerful desk calculator function (ala the later UNIX "bc" function),
and an integrated, disk-based help system.
In spite of my complaints about the System/3 instruction set, the BASIC system actually performed well.</p>
<p>In addition to the BASIC project being my first IBM management job,
I also met my wife while working on this project;
she was an IBM programmer in Boca working on operating system development.
(In fact, as a nice touch, my System/3 Model 6 arrived literally on the day of our 42th anniversary.)</p>
<p>After my work on the System/3 Model 6 was finished, I worked on the design of another small computer system.
That project was cancelled and, in the Fall of 1971, I moved to Rochester where my new job was ss
the second-line manager of the system software for another new small computer system:
the <a href="http://www-03.ibm.com/ibm/history/exhibits/rochester/rochester_4017.html">IBM System/32</a>.
Amazingly, the museum also has our own System/32, <a href="../s32/">check it out</a>.</p>
<h4>The First IBM PC?</h4>
<p>The IBM System/3 Model 6 hardware together with its BASIC software package was,
I claim, the first "IBM Personal Computer"; that is,
a computer on a desk with a keyboard and a CRT display device, a printer, a removable disk drive,
and software for a user to program in interactive BASIC.
Effectively, this system could do what the Apple II did, only much better (internal fixed disk, 64KB virtual memory, etc.),
and 9 years earlier.</p>
<p>The only flaws with our solution was that it was a large desk with an large lump on one end,
it weighed 1,300 lbs, it used 220V power, and it rented for about $1,000 a month.
Accordingly, sales were low and the BASIC software received little attention in the market or within IBM.
(In spite of the BASIC system having no visibility, I and another person from my department [Brad Beitel] went on to be very successful at IBM.)</p>
<h4>The Museum's Model 6</h4>
<p>My Model 6 was procured in August, 2013.
It came from the original owner who had used it to run business applications for her small company.
It was used for this purpose until about 1985 when it was decommissioned by IBM and stored in the owner's basement,
where it gradually became buried under typical basement storage items (show in Figure 23).</p>
<p>Getting it physically to the museum (in Austin) from the basement in Omaha was a complicated logistically operation,
but it finally made it.
(Mark Rothbauer of Centaur was the key person here; he went to Omaha and freed it from the basement.)
The system's condition is dusty but good considering the it is over 40 years old and hasn't been used for over 25 years.
The usage meter indicates 2977 hours powered on.
The Model 6 also came with 17 disk packs including the operating system, as well as a lot of documentation.</p>
<p>I (with help from others here at Centaur) will try to restore it to running condition.
The likely things that need repairing are replacing electrolytic capacitors and drive belts,
but my biggest worry is the disk drive.
Stay tuned for progress.</p>
<p>The Model 6 is very rare these days.
A <a href="http://www.ibmsystem3.nl/remaining.html">interesting web site that covers System/3 family</a> tracks existing devices.
It knows of only two other Model 6's, neither of which are operational.</p>
<h4>A Walk-Around</h4>
<p>Figures 3, 4, and 5 show the general layout.
Figure 6 shows the keyboard, which is very nice, especially for that time. Included are a numerical keypad and 16 function keys.
The keyboard complex also included the basic controls for the operator along with "halt code" lights which the program can set.
Figure 7 show detail of the 16 lights corresponding to the function keys.
These keys are used by the application program and thus have user-writable labels on the lights to remind the operator of what the keys do.
To the right of the function key labels there are another eight output lights that can be set by the program.
These also have user-writable labels and are used to tell the operator what function to perform next.</p>
<p>Figure 8 shows the back of the swing-out logic gate with its wiring. There are five logic boards installed. (The missing one is for a communication option).
Figure 9 show the other side of the gate and Figure 10 shows it with the board covers removed.
Figure 11 shows a closeup of a particularly interesting board.
On the left of this board are eight pluggable cards, each containing many modules, primarily IBM MST logic modules (more on this technology below).
On the right of this board is the magnetic-core memory module.
Our system is fortunate in that it has the largest possible Model 6 memory: 16KB.
The smallest memory for a Model 6 was 8KB. (The BASIC software package I worked on ran in only 8KB).</p>
<p>(The Model 6 was probably the last IBM computer to use core memory.
Subsequent System/3 models used solid state memory as did the S/370 IBM mainframe family at this time.)</p>
<p>The System/3 instruction set was very simple. It had 28 instructions, two index registers,
a condition flags register, and some control registers.
There were no accumulator or general purpose registers;
operations were performed memory-to-memory.
For example, the ALC (Add Logical Characters) instruction (4-6 bytes long, based on addressing options)
adds one memory field to another field, one-byte at a time for a specified length from 1 to 256 bytes.
Instruction timing is simple: 1.52μs for each memory byte touched.
For example, a 4-byte ALC instruction moving 16 bytes in memory takes 30.4μs.</p>
<p>Figure 12 shows the CE (Customer Engineer) control panel. This was our primary debug tool when I was developing code for this system.
We would single step the code examining processor state using the lights.
You could also easily modify memory from this console.
Figures 13 and 14 show the back view of the system including the cables the connect the two halves together.
For shipping and installation, the system could be separated into two components: the "table" part, and the "box" part.
(Our system had to be separated into two pieces in order to get it though doors.)</p>
<p>Figure 15 shows the back of the 5444 disk drive unit at the left of the table (from the front).
There is a compartment for a second 5444 under this, but our system only has one disk drive.
There were two models of this drive; the larger had a capacity of 5MB split equally between a fixed platter and a removable platter.</p>
<p>Figure 16 shows the disk drawer opened with the removable disk installed.
Below this is a fixed disk platter that shares the same access arm as the removable disk.
Figure 17 shows the disk drawer with the removable disk removed.
The fixed disk is barely visible through a hole on the right (where the index transducers are).
Figure 18 shows a view looking at the retracted heads and the cleaning brushes on the right.</p>
<p>Figure 19 shows some of the documentation received and five disk cartridges containing system software.
Figure 20 shows 12 more cartridges that we have.
Figure 21 show a closeup of the removable disk cartridge with the access holes for the heads and cleaning brishes.</p>
<p>Finally, Figure 22 shows the a cassette tape used by the IBM Customer Engineer to run diagnostics and deliver software fixes.
This was used since the only removable medium is the disk cartridge, too large for the CE to haul around.
So, looking at Figure 12, there is an audio jack ("J1") used to plug in a ordinary tape player.</p>
Sperry S-1 Bombsight2013-03-15T00:00:00ZG. Glenn Henryurn:uuid:1903655e-b4b7-3af6-afd5-a8f64c5d6612<h3>Sperry S-1 Bombsight</h3>
<p>It turns out that the famous Norden bombsight was
not only U.S. bombsight of World War II.
The first bombsight accepted by the Government was the Sperry S-1 that was developed in
the 1930's.
It was designated as "standard" equipment in March 1941 and was
used in some U.S. Army Air Forces bombers early in World War II,
primarily <a href="http://en.wikipedia.org/wiki/Consolidated_B-24_Liberator">B-24 Liberators</a>.
However, all contracts for production of the Sperry sight were canceled in late 1943.
Many claim that the Sperry S-1 was a superior design to the Norden and clearly politics were involved in the
procurement decisions.
The September 1999 issue of IEEE Spectrum has a
very good <a href="http://thevaluesell.com/images/LSearle_bombsight.pdf">article</a>
on this topic, appropriately called <em>The Bombsight
war: Norden vs. Sperry</em>.</p>
<p>As shown in Figures 1 and 2, the Sperry S-l sight is essentially a cube with control (data input) knobs on each side
and a vertically mounted telescopic viewing system. (Figure 2 shows the fact that we just acquired another S-1; see discussion of it below).
The data input knobs are similar to the Norden bombsight, but were positioned on both sides of the instrument.
Primary controls on the right side were concentric azimuth rate and displacement knobs,
a cross-trail correction knob, a trail knob for setting in the standard value for the bomb,
and a caging control for the vertical gyro.
On the sight's left side were the concentric range displacement and rate knobs,
a time-of-fall knob for setting in this bombing table datum,
an angle sweep knob for initial location of target, and a caging control for the azimuth gyro.
In Figure 1, the slanted portion at the bottom of the front is the viewing port of the telescope.</p>
<p>Figures 3,4 and 5 show some of the complicated mechanicals inside the S-1.
It is hard to see, but Figure 5 shows the front of a disc integrator.
The rotating disc in seen sticking up above the mechanism at the rear and the brass component
is part of the mechanism that adjusts along the radius of the disc.</p>
<p><strong>New news 3/2013:</strong> Even though I already have 1+ S-1 bombsights (see below),
I just got another one which has some interesting and new (to my collection) features:</p>
<ul>
<li>It has a modification ("M-2") that. was added to the S-1 family in 1943. As shown in Figure 6, this modification adds an
important feature to the original S-1: "tangent scales".
The tangent scale mechanism is used to indicate release points for high altitude and low altitude attacks.
Other changes in the M-2 mod are changes in the azimuth gearing, including a new clutch, and some ergonomic changes to the control knobs.</li>
<li>As Figure 7 shows, it came with an original manual for the M-2 modification. I have never seen such before.</li>
<li>It also came with its logbook, shown in Figure 8. The logbook show things like test history, modification history,
and operational (bombing) history. The later pages have been torn out but
in the remaining stubs one can see that this device has a real history of being used in bombing flights.</li>
<li>It was actually manufactured by IBM in Endicott, as shown in Figure 9.</li>
<li>And, as shown in Figure 10, It arrived in the original transport case for the S-1 bombsight.
The bombsight in its case weighed about 150 pounds.</li>
</ul>
<p><strong>New news 10/2010:</strong> my original S-1 arrived in many pieces and I had long planned
to reassemble it but reality has set in (reality = I never will get around to this)
so I've now acquired a complete S-1.</p>
<p><strong>Original news:</strong> I have acquired a disassembled S-1 as shown in Figures 11 and 12.</p>
<p>Also, Figure 13 shows the control panel for an A-5 autopilot which was developed to go with the S-1 bombsight.
The A-5 seems to be the first all-electric three-axis autopilot (using tubes, of course).</p>
Navcor Analog Computer2013-01-10T00:00:00ZG. Glenn Henryurn:uuid:bfcafb1f-e535-3b33-8597-5f28f25e4aa5<h3>Navcor Analog Computer</h3>
Sperry P-4 (Gunsight) Computer2013-01-10T00:00:00ZG. Glenn Henryurn:uuid:5ac594dd-1e87-3ea2-91bc-799135ccb81d<h3>Sperry P-4 (Gunsight) Computer</h3>
<p>Here is a extremely rare device, an electromechanical Sperry P-4 (Gunsight) Computer.
The only good information I could find about this device can be found in this <em>very interesting</em>
<a href="http://www.edn.com/design/analog/4402983/Design-hindsight-from-the-tail-gunner-position-of-a-WWII-bomber-Part-one">article describing another museum's (a real one) P4</a>.</p>
<p>Briefly, the background is that the P-4 was originally designed as part of a central fire control system for the remote control of bomber gun turrets primarily for the
<a href="http://en.wikipedia.org/wiki/Boeing_B-29_Superfortress">B-29</a> and
<a href="http://en.wikipedia.org/wiki/B-32_Dominator">B-32</a> bombers (the B-32 was a backup in case of problems with the B-29 program).
Ultimately, the Sperry P-4 was not chosen by the Army and was replaced by the GE-designed fire control system covered
elsewhere in the museum.
According to the referenced article, only 460 P-4 systems were contracted for and the number actually built out of these 460
is unknown as the contract was canceled before they were all built.
There were several factors that lead to the GE system being chosen, including P-4 schedule delays,
but one of the most critical was the small field of view from the periscope.</p>
<p>Our P-4 is about six-feet tall and weights about 200 pounds!.
Figure 1 shows the front of the entire device (a water bottle show the scale).
The periscope on the top looked out through a window on the top of the centrally located sighting compartment on the plane.
Just below the base of the periscope, Figure 2 shows the eyepiece for viewing (our device is missing part of the the eyepiece),
and the controls and readouts for items like airspeed and altitude.
Below that, shown in Figure 6, are the steering controls for manipulating the left-right and up-down of the view through the periscope.
Figure 7 show the mechanism to translate the control movements.
Figure 3 show the back of the device, slanted (as can be seen in Figures 4 and 5) to fit (I guess) the upper curve of the fuselage.
There was also a foot pedal connected to a rod on the side for zooming the view.
Our device is missing this foot pedal.
It also has damaged side panels.
Otherwise, the insides seem pristine: in Figure 8 notice the grease on the three-dimensional cams.</p>
<p>The real interest is the internal computing mechanisms show in the side views of Figures 4 and 5 (obviously the side panels have been removed.).
In person, the details are very impressive.
Much of the mechanical computing elements are not easily seen in these pictures.
Figure 8 is just one example of the complexity that lies deeper within the case.</p>
<p>Figures 10,11, and 12 show the periscope with its case removed.
There are three controls attaching to the computer unit: pan, tilt, and zoom.
These controls is transferred from three rods that attach to matings at the bottom of the periscope.
There is also a heating element.
Note the very small optical element (a prism); it is about the size of a thumbnail.</p>
IBM 705 Console & Components2012-12-19T00:00:00ZG. Glenn Henryurn:uuid:e94a74bb-60b4-3243-81c7-8a8d7ba60ebb<h3>IBM 705 Console & Components</h3>
<p>The museum has a control console from a <a href="http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP705.html">IBM 705 computer</a>.
I believe this to be very rare item since the 705 was first shipped in late 1954 and was withdrawn in early 1960.
That's a long time ago and there can't have been many shipped during that short period
(but I haven't found credible numbers for the total shipped).
Also, the 705 was quite expensive: about $590,000 in 1954 dollars.</p>
<p>(Note that on our console the original IBM 705 banner has been replaced with a customer's banner ("Confederation Life").
Since computers were so rare in the 1950's they were usually proudly displayed in a "glass house" by their users,
often with the user's name on them.)</p>
<p>The IBM 705 architecture was heavily optimized for business applications
such as billing, payroll, accounts receivable, and inventory control,
as opposed to computationally intensive applications.
In early computers, hardware was so expensive and limited in capability that the each computer
was specifically designed for certain types of applications,
with a common differentiator being character handling vs. arithmetic computation.
In the 1950's IBM introduced several 700-series computer starting with the pioneering IBM 701.
The IBM 702, IBM 705 were optimized for business applications,
while the IBM 704 and IBM 709 were optimized for engineering and scientific applications.
Shown on the left is a pre-System/360 "family tree" drawing from IBM of its early computers which illustrates the various model and their introduction dates.
This application optimization continued through later transistorized descendants of these 1950-era computers (such as the IBM 7080 which was the follow-on to the 705)
until the introduction in 1964 of the IBM System/360 family, which had a "general purpose" architecture.
Even after that, low-end IBM computers such as the IBM 1130,
<a href="http://en.wikipedia.org/wiki/IBM_System/3">System/3</a>, System/32, and System/38
were optimized for specific applications.
And, process-control applications were addressed by the specialized IBM 1800, IBM System/7,
and <a href="http://en.wikipedia.org/wiki/IBM_Series/1">IBM Series/1</a> families.</p>
<p>The IBM 705 used vacuum tubes (about 1,700 of them) for its logic and used magnetic core memory for storage.
Its instruction-set architecture was heavily optimized for business applications.
Of special note is the fact that memory was organized into 7-bit "characters"
and the two accumulators (corresponding to current processor registers) each contained 256 characters.
The memory size was either 20,000 or 40,000 characters.
A load from memory into the accumulator took about 17 microseconds.
The main input and output was magnetic tape (5M characters per reel), but a card reader and punch as well as a printer could be directly attached.</p>
<p>In addition to the control console, we also have some electronic components and original documentaion (some probably rare) for the IBM 705.
We have several of the pluggable processor logic elements as shown on both sides along with an ad for the IBM 701 showing the same type of pluggable unit.
Also shown is our stack of more than 25 original IBM documents about the 705 including the introductory volume
of the Customer Engineer (CE) internal documentation. This document describes the details of the logic elements and memory components.</p>
<p><strong>New arrivals 12/2012</strong></p>
<p>One of the most important peripheral I/O devices in a IBM 705 system was the IBM 767 Data Synchronizer.
Figure 14 show a picture of the 767 from the IBM 705 Reference manual.
The Data Synchronizer was the forerunner of what later became IBM's System/360 "Data Channels".
It attached up to 10 IBM 729 tape Drives and allowed overlapping reads and writes across these devices to and from the main memory of the IBM 705.
In today's terms it was a "multiplexed buffered DMA (Direct Memory Access) controller".</p>
<p>The museum contains a IBM 767 control panel, as shown in Figures 15, 16, and 17.
Note that the front panel has a large bus connector on it.</p>
<p>Figures 18 through 21 show two other control panels that I am sure come from pre-System/360 IBM equipment,
but I have not been able to identify them yet.</p>
Zentronik Drum Memory2012-12-15T00:00:00ZG. Glenn Henryurn:uuid:8be87873-29bb-3318-9b81-8f75f7f5338f<h3>Zentronik Drum Memory</h3>
<p>Before there were discs, magnetic drum memory was the state-of-the-art storage device.
In fact, earlier computers like the IBM 650 had no other memory device (no core memory, for example) other than its drum.
Here is an example of an early drum memory made behind the Iron Curtain by (I believe)
Zentronik Works in East Germany (GDR) sometime in the 1960's.
The Zentronik company manufactured several small computers as mentioned
<a href="http://de.wikipedia.org/wiki/Kombinat_Zentronik">here</a>.</p>
<p>This wonderful device is a <strong><em>very generous gift</em></strong> from Dr. Čestmír Čejka, a collector in the Czech Republic. He writes:</p>
<blockquote><p>It is a vintage Easten German very early magnetic memory unit made by
Zentronik in the city Zella-Mehlis in Saxonia. The works in Zella-Mehlis
were well known already before the war for its production of
electro-mechanical business machines, such as Mercedes Euklid.
Beginning about 1960, this factory started the first programme of
manufacturing of digital computers in the Eastern block. This memory
belongs to some of these earliest computers. In my opinion it was made in
the second half of the 1960's.</p>
</blockquote>
<p>Figure 1 shows the whole unit. The drum motor sticks up on top of the drum mechanism with the read/write heads surrounding the drum.
Figure 2 shows the rear panel of this device with its connections to the rest of the computer.
A closeup of the label showing the manufacture's name and city is shown in Figure 4.
Figure 3 is a closeup of the head mechanisms.
There are eight columns with 16 heads each.
Its not clear if the heads are a combined read/write or just a read read or a write head.</p>
<p>Details like rotation speed of the drum, data organization, data rates, etc. are not available.
I've hesitated to take the drum out so far since it seems difficult and I didn't want to damage the unit.</p>
IBM & RAND JOSS terminal2012-12-15T00:00:00ZG. Glenn Henryurn:uuid:d88146c9-9b17-3fe8-a0be-7544f4775390<h3>IBM & RAND JOSS terminal</h3>
<p><a href="http://en.wikipedia.org/wiki/JOSS">JOSS (JOHNNIAC Open Shop System)</a>
was a new computer language, which together with new remote terminals,
attached to RAND's
<a href="http://en.wikipedia.org/wiki/JOHNNIAC">JOHNNIAC mainframe computer</a>,
comprised one of the first time sharing computer systems.</p>
<p>This <a href="http://www.rand.org/content/dam/rand/pubs/reports/2008/R918.pdf">RAND document</a>
from RAND contains more information about the language and using the JOSS system.
Of particular interest to us is the special console designed for JOSS,
which is described in detail in
<a href="https://www.rand.org/content/dam/rand/pubs/research_memoranda/2006/RM5218.pdf">this RAND report</a>.
The JOSS console comprises a modified IBM 731 "input-output" electric typewriter attached to a specially designed control logic
which interfaces between the typewrite and a full-duplex communication channel.
Figures 1 and 2 come from this RAND report showing the console: the typewriter on top of the control box.</p>
<p>The museum contains an instance of the JOSS console control box.
Figures 3 and 4 show the front and back sides.
Figure 5 shows one of the 50 cards containing in the control unit's logic. This appears to use diode logic.
Also in Figure 5 we see the RAND label and serial number of our controller.
Figure 6 show some information pasted to the side of the controller,
and Figure 7 show some of the status lights on the top of the controller.</p>
IBM Card Equipment Programming Plugboards2012-12-12T00:00:00ZG. Glenn Henryurn:uuid:bf4cf2db-9591-3b9f-9c8d-22984b4e24f2<h3>IBM Card Equipment Programming Plugboards</h3>
<p>I love IBM card equipment!</p>
<p>Until the early '60s, most business applications were done on standalone card processing units (called by IBM <a href="http://en.wikipedia.org/wiki/Unit_record_equipment">unit record equipment</a> by IBM) like the ones in our collection (shown following this topic).
Even when computers started to be used, most programming was done on punched cards and all computers had punched card input and output.
It wasn't until the middle seventies at IBM that we internally switched from card input to CRT terminals.
Figure 1 is a box of 2000 fresh punched cards just waiting for our machines to use. (When I programmed on punch cards at IBM, our programs consisted of several trays of cards,
each try containing several of these boxes.)</p>
<p>Standalone card equipment ranged from simple devices like keypunches to primitive computer devices like the
<a href="http://www.columbia.edu/acis/history/602.html">IBM 602 Calculating Punch</a> which could do multiplication and division.
All but the simplest card equipment could be "programmed" by wiring a control board like the ones shown here (often called a plugboard).
Other than the fairly rare calculating punches, the most advanced card devices were accounting (also called tabulating) machines like the
<a href="http://en.wikipedia.org/wiki/IBM_407">IBM 407</a>
which read cards and printed a report based on the card data using some counters and simple branching logic (as defined by the plugboard program).
These tabulating machines were the computers of their day and were pervasively used in business.</p>
<p>Accounting machines could also be used in non-obvious ways;
in my first computer job in 1963 (application programming an IBM 7090 in Fortran and assembler),
one of the scientists had programmed an IBM 407
to do matrix multiplication.
(Here's a technical paper on this <a href="../../reference/407 p442-boyell.pdf">magic</a>. Figure 2 shows a page describing the programming.)
Later in college (1965-67) the computer we used (an <a href="http://en.wikipedia.org/wiki/IBM_1620">IBM 1620</a>) had only card input and card output.
The output punched cards were hand carried from the computer to the 407 for listing.
(The 407 was also used for many business tasks such as producing the student grade reports.)
So, since every run I made ended up on the 407, I naturally learned how to program the 407 to do "cute", but useless things.
We had lots of 407 boards, each preprogrammed with a particular application, similar to having multiple computer programs today.</p>
<p>Here is my collection of plugboards for IBM card equipment.
Figure 3 is the board for an <a href="http://en.wikipedia.org/wiki/IBM_1620">IBM 402</a> accounting machine, an earlier version of the 407,
and Figure 4 show how the plugs come out of the other side.</p>
<p>When the plugboard is inserted into the machine, the plugs contact sockets that are hardwired to
card read brushes, card punch controls, and internal counters and other logic.</p>
<p>Figure 4 also shows the label of what this program supposedly did (payroll).
Figure 5 shows our four <a href="http://en.wikipedia.org/wiki/IBM_557">IBM 557 Alphabetic Interpreter</a> plugboards.
Since we actually have a 557 in the museum, having multiple boards allows us to have different programs ready to us.
On the left side are some programming "statements" (plug wires) ready for more programming.</p>
<p>Figure 6 shows the plugboard for an <a href="http://www.columbia.edu/acis/history/collator.html">IBM 088 Collator</a>.
Figure 7 shows the plugboard for an <a href="http://www-03.ibm.com/ibm/history/exhibits/650/650_ph13.html">IBM 533 Card Read Punch</a>.
The 533 is particularly important as it was the input/output device for the <a href="http://en.wikipedia.org/wiki/IBM_650">IBM 650 computer</a>,
commonly considered to be the first mass produced computer.
The 650 was the first computer I ever saw in person (on a high-school field trip to the engineering lab at UC, Berkeley),
and it had a great influence on my later choice to specialize in computers.</p>
<p>Figure 9 shows the plugboard for an <a href="http://www.columbia.edu/acis/history/602.html">IBM 602 Calculating Punch</a>.
Figure 8 is a closeup of this board showing some of the controls for multiplying and dividing.
Figure 10 shows our three plugboards for our <a href="http://en.wikipedia.org/wiki/IBM_514">IBM 514 Reproducing Punch</a>.
(Also shown are some programming plugs; these can be used on all the IBM boards.)
Figure 12 show the control board for a rare device: the IBM 063 Card-Controlled Tape Punch.
This device read cards and punched the corresponding values in <em>paper tape</em>.</p>
<p>Finally, Figure 11 shows a particularly rare piece: the control plugboard for an <a href="http://en.wikipedia.org/wiki/IBM_6400_Series">IBM 6400 Accounting Machine</a>.
This device is little know and I've never seen one (as opposed to all the other devices discussed in this section).</p>
<p>Figure 13 shows a new variety of a 402-403 control board.
Note that Figure 3 shows our other 402-403 board and this new one is subtly different.
Figure 14 shows a newly arrived control board for an IBM 85 collator.
The model 85 is an earlier collator version that the Model 88 whose control board is shown in Figure 6.
Note that the 85 board is much different (simpler) than that for the 88.
It seems that every different version of the same type of device (collator, interpreter, etc.) had a different control board.</p>
<p>Finally, I now possess a IBM 407 control board. As described above, this is my favorite card devices and
the epitome of card processing complexity.
Figure 15 show the large (and heavy, about 25 pounds) 407 control board with an apparently working program.
Figure 17 shows the label of the program which is "PAYROLL/CALC FICA/RETIREMENT/TAXABLE WAGES".
This payroll application is a typical 407 function (our college 407 was used monthly for this very purpose).
Figure 16 shows a close-up of some of the program's logic.
The big orange and gray blob things are splitters and combiners of signals.</p>
<p>I'm getting too many of these to photograph them, so here is
my inventory of IBM card equipment control panels:</p>
<ul>
<li>Type 46-47 <a href="https://en.wikipedia.org/wiki/IBM_650">IBM 650 system</a></li>
<li>Type 77 <a href="https://www-03.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV4004.html">IBM 77 Collator</a></li>
<li>Type 85 (x2) IBM 85 Numeric Collator</li>
<li>Type 88 IBM 88 Numeric Collator</li>
<li>Type 88-2 IBM 88 Numeric Collator</li>
<li>Type 101 <a href="https://en.wikipedia.org/wiki/IBM_101">IBM Statistical Sorting Machine</a></li>
<li>Type 323 IBM 323 Card Punch, part of <a href="https://en.wikipedia.org/wiki/IBM_305_RAMAC">RAMAC 305 system</a></li>
<li>Type 380 IBM 380 Console, part of <a href="https://en.wikipedia.org/wiki/IBM_305_RAMAC">RAMAC 305 system</a></li>
<li>Type 402-403 (x4)</li>
<li>Type 407</li>
<li>Type 513</li>
<li>Type 514 (x2)</li>
<li>Type 513-514-523</li>
<li>Type 521-541</li>
<li>Type 548</li>
<li>Type 553</li>
<li>Type 557 (x2)</li>
<li>Type 604 (x2) <a href="https://en.wikipedia.org/wiki/IBM_604">604 Electronic Card Calculating Punch</a></li>
<li>Type 834-836 IBM 870 Document Writing System</li>
<li>Type 6400</li>
</ul>
Farrand Y-7 Bombsight2012-12-10T00:00:00ZG. Glenn Henryurn:uuid:de10a6be-7bc9-3b3c-9f03-f39295b6afe3<h3>Farrand Y-7 Bombsight</h3>
<p>This is another massive optical bombsight made by Farrand.
Figure 1 shows the whole 80 pound beast compared to a soda can.</p>
<p>The only reference I can find to it is from the Air Force Systems Command, Historical Publication Series,
Development of Airborne Armament, 1910-1961:</p>
<blockquote><p>The vertical periscopes did not remain immune to the continuing drive for improvement.
First, Farrand altered the Y-3 vertical periscope to utilize a shallower optical dome;
the revision was designated Y-5, and scheduled for installation in the B-52,
Next, the Armament Laboratory published a design exhibit for a 50-inch-long vertical periscope, designated the Y-7,
which incorporated the shallow dome of the Y-5. Both Farrand and Eastman Kodak were to manufacture the Y-7.
This was the "ultimate" vertical periscope for the "K-Series" system,
and was intended for installations in the B-52, the B-36, and the "large nose" B-45.
In January 1952 Farrand contracted to design and construct two prototype Y-7's. One month earlier,
Farrand had delivered the first model of the Y-5 vertical scope to Boeing's Seattle plant for installation in the XB-52 aircraft.52</p>
</blockquote>
A-4 "Gun Bomb Rocket" Sight2011-12-10T00:00:00ZG. Glenn Henryurn:uuid:fc93aafc-0b7d-3f94-8d24-3cc8869baf8e<h3>A-4 "Gun Bomb Rocket" Sight</h3>
<p>This is the sighting element and the computing element of the gun/bomb/rocket aiming sight used on <a href="http://en.wikipedia.org/wiki/F-84">F-84 Thunderjet</a>
and <a href="http://en.wikipedia.org/wiki/North_American_F-86_Sabre">F-86 Sabrejet</a> fighters.
Figures 1-3 show the computing element, and Figures 4-9 shows the separate sighting element.
Figures 10 and 11 show information about the A-4 from from an F-86 flight manual.</p>
IBM System/360 Read-Only Storage (ROS)2011-12-10T00:00:00ZG. Glenn Henryurn:uuid:9876dd63-95bf-326d-83bb-1a8c30191d97<h3>IBM System/360 Read-Only Storage (ROS)</h3>
<p>Extensive <a href="http://en.wikipedia.org/wiki/Microcode">microcode</a> allowed the System/360 to provide a compatible
instruction architecture and compatible I/O across many models having significantly different performance.
Among the original offerings, the Model 30, 40 and 50 all had hardware significantly less powerful than the System/360 instruction
architecture and implemented the instructions via microcode.</p>
<p>The microcode was contained in a <a href="http://en.wikipedia.org/wiki/Control_store">control store</a>
implemented as read-only storage, or ROS
(this is IBM's term, today we call it read-only memory, or ROM).
Then, as today, ROS is implemented as a two-dimensional array of word-lines, which select the output for a particular address,
and the orthogonal bit lines which are the outputs.
Since only one word line is active at a time, the output for each bit of selected the ROS word can be defined
by either no connection at the intersection of the word-line and bit-line, or by connecting the word line to the bit line through a diode.
That is, when a bit-line is asserted, the output of the ROS is defined by the connects or no connects to the bit lines for that particular address.
The difference among the many implementations of ROM are primarily in the choice of this connection mechanism.
Different types of "diodes" affect the speed, size, and ability to change the ROS.</p>
<p>All except the high-end model of the original introduction used microcode to implement the System/360 architecture.
Three different types of ROS were used: Card Capacitor ROS, Transformer ROS, Balanced Capacitor ROS.
We have samples of all three of the types.
Figure 1 shows a storage card of the Model 30's Card Capacitor ROS.
The storage card looks like an IBM punched card except it is made of Mylar and has metal lines etched on it.
(Much more about this ROS design can be found in J.W.Haskell,Design of a Printed Card Capacitor Read-Only Store, IBM Journal, March 1966.)
Figure 2 is a closeup of the card.</p>
<p>Each card has 12 word lines corresponding to the 12 rows on a standard punched card.
The contacts for the word lines are on the right in the picture.
Each word line attaches to 60 bit "pads" (again corresponding directly to the punch positions in a standard IBM card).
The metal pad can be eliminated by punching that position with a standard card punch.
Thus, bits in the microcode word for each word line are defined by the metal pad being present or absent.</p>
<p>The ROS cards are placed in a frame where bit lines run vertically aligned with each of the 60 column.
A thin sheet of Mylar goes between the card and the bit lines to form the capacitive coupling
between the metal pad and the word line.
The cards are mounted on a 20x12" board with four cards on each side.
The mechanics of the boards (ground planes, pressure on the card, insulator thickness, etc.) are such that the coupling ratio between
a punched and unpunched pad is at least 10:1.
The boards are assembled into a module to form the complete ROS.
The Model 30 ROS used 43 boards for a capacity of 4032 60-bit words (with one spare board).
The access time for this ROS is 0.75 microsecond.</p>
<p>It was relatively easy to change ROS cards in installed systems.
This flexibility was important because the Model 30 had an option to emulate the machine instruction set of the very popular IBM 1401.
Figure 9 (taken from another source) show IBM Field Engineer changing the ROS for a Model 30.</p>
<p>Figure 3 show the code portion of a module from the Model 40 Transformer ROS.
Instead of a capacitor forming the connection between the word line and the bit line,
the TROS used a transformer at the intersection.
Figure 4 is a closeup of one of the Mylar strips containing two 54-bit ROS words.
The word line is etched on the strip and completes a loop from one end back to the same end.
The current is routed in one of two ways around a central metal core for each bit.
The current direction around the core determines whether it is sensed as a 0 or 1.
The current direction is controlled by punches that disconnect one side of the current loop around each bit post.
(Much more about this ROS design can be found in D.M.Taub,T he Design of Transformer (Diamond Ring) Read-Only Stores, IBM Journal, September 1964.)</p>
<p>Figures 5 & 6 show the "bit line" sensing mechanism that sits on top of the metal cores for each bit.
Each module has 128 tapes, each storing 2 words. A total of 16 modules formed the ROS for the Model 40, for a total of 4K words.
The access time was 240ns with a cycle time of 625ns.
Figure 8 shows 8 modules of the Model 40 ROS; another 8 modules are behind the visible ones.</p>
<p>Figure 10 is part of the Balanced Capacitor ROS of the <a href="http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2050.html">IBM System/360 Model 50</a>.
It is called balanced because the capacitance load on the word line is the same regardless of the pattern of bits.
This is as opposed to the Card Capacitor ROS shown in Figure 1 where the number of 1 bits changes the word line capacitance.
The balanced approach allows a faster access time: the timing of the Model 50 was 90 ns access and 200 ns cycle.
The disadvantage of the balanced approach is that the bit patterns have to be manufactured into the card,
as opposed to the card capacitor approach where new ROS bits can be created on site.</p>
<p>Figure 11 shows a closeup of the card. A ROS bit is represented by two locations along the word lines.
There are two "word" line for each bit: one is the drive line to trigger reading.
Attached to this line is one "pad" shaped per bit.
There are two sense lines for each bit on the sensing plane that the ROS cards are pressed against:
one for 1 and one for 0.
The position of this bit pad over the two sense lines determines whether it is represents a 1 or 0.
The other word line a "balance" line for attaching the complement of the bit flags.
For example, compare the first two bits of the top two bit rows in Figure 11.
The first two bit pads are the same: the right pad is attached to the drive line.
The next bits are different: top row has left pad attached, and bext row has right pad attached.</p>
<p>(Much more about this particular ROS design can be found in S.A.Abbas, A Balanced capacitor Read-Only Storage, IBM Journal, July 1968.)</p>
Unknown Farrand Sighting Mechanism2011-12-10T00:00:00ZG. Glenn Henryurn:uuid:2b4853b7-c52f-3afb-9e09-a0534c7e33e7<h3>Unknown Farrand Sighting Mechanism</h3>
Fairchild A-4 (MX-10) Line-of-Position Computer2011-11-27T00:00:00ZG. Glenn Henryurn:uuid:7797e2b8-efd5-3199-85b5-2ea35760ec42<h3>Fairchild A-4 (MX-10) Line-of-Position Computer</h3>
<p>This wonderful device is a self-contained mechanical computer from the late 1930's that calculates a type of
<a href="http://en.wikipedia.org/wiki/Celestial_navigation">celestial navigation</a>
called <a href="http://www.math.ubc.ca/~cass/courses/m308-02b/projects/jackson/Page3.html">"line of position"</a>.
(If you're not fluent in celestial navigation, it more complicated than one might think.
If you want to know more, there are many of good references on the web and
<a href="http://www.celnav.de/astro.zip">here</a> is a free book I recommend.)
Another great reference is Technical Manual TM1-206, 1941 (Figure 12)
which includes a description of how to use the A-4 computer (Figure 13).</p>
<p>A very simplified description of line-of-position navigation is that given the time of day
and sighting data (from a sextant) of the sun or another celestial body like a star,
and by using precomputed tables, you can calculate the coordinates of a line on the surface of the earth,
upon which you must be.
Two such sightings and calculations produce two lines, whose intersection is where you are.
(Technically, these "lines" are not lines but are "circles of equal altitude" which intersect at two positions,
but in practice the position is not ambiguous.)
The line of position approach was discovered in 1837 by <a href="http://en.wikipedia.org/wiki/Thomas_Hubbard_Sumner">Thomas Sumner</a>
(his original publication describing the method is
<a href="https://www.google.com/search?tbo=p&tbm=bks&q=inauthor:%22CAPT.+THOMAS+II.+SUMNER%22">here</a>)</p>
<p>Although celestial navigation from a ship and an airplane are conceptually similar,
there are important differences, among these are the fact that
airplanes lack a stable horizon, experience high acceleration, and rapidly change their position.
This means that it is important to be able to make position estimates accurately and rapidly.
Before the A-4 computer, the line of position calculations required solving several trigonometric formulas
using data from massive <a href="http://en.wikipedia.org/wiki/Nautical_almanac">celestial almanacs</a>.
These calculations were done by hand or using specialized slide rules.
The A-4 performs these calculations with greater precision than slide rules,
and most conveniently, has the almanac values for the sun built into it,
thus eliminating almanac lookup in many cases.</p>
<p>As can be seen in Figures 6-10, the computation mechanisms are completely mechanical and are quite complicated.</p>
<p>The astronomical almanac data for the sun is machined into a replaceable module that covers a particular quarter of a year.
Our data is for fourth quarter, 1938 (Figure 5).
The replaceable unit is the shiny mechanism in Figure 9.
Close examination show part of a large gear with a track cut in it.
This is the data.</p>
<p>An interesting historical note: the Fairchild A-4 was used by Howard Hughes of his
<a href="http://tinyurl.com/7855chq">flight around the world</a> in 1938.</p>
MG-1 Mechanical Central Air Data Computer2011-11-27T00:00:00ZG. Glenn Henryurn:uuid:7083d369-3907-30b7-96f2-b817f825c280<h3>MG-1 Mechanical Central Air Data Computer</h3>
<p>This is a Bendix MG-1 Air Data Computer.
It was first used in the <a href="http://en.wikipedia.org/wiki/North_American_F-86_Sabre">F-86 Sabre</a> jet fighter.
The F-86 was effectively the first U.S. jet fighter, first deployed in 1949.</p>
<p>I actually have two (slightly different versions) of the MG-1.
Figures 1 and 2 show a complete unit.
Figures 3-6 show a second unit where I have cut the sealed container to expose the wonderful innards.
Inside is a mixture of mechanical pressure sensors (the two cylinders at the top of Figure 3),
many mechanical calculating mechanisms, and a number of electrical sensors.</p>
3D-Gyro Navigation Device2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:989d464a-d9e3-333a-a26b-40e12528ac70<h3>3D-Gyro Navigation Device</h3>
<p>This is yet another not-a-computer, but it is interesting.
It's a compact 3D gyroscope obviously used in some inertial navigation system.
Its cylindrical shape (about 9 inches in diameter and 16 inches in length) suggests that it came from a missile of some sort.
It is heavy for its size, about 30 lbs.</p>
<p>The block cylinders within the gimbals in the closeup pictures are the gyros.
There are two pairs of them mounted at right angles to the other pair.</p>
<p>There are no identifying labels that I can find, but the last service sticker was from 1961.</p>
B-36 A-1A Bomb Release Computer2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:30e1cf51-3c48-368c-8629-e3acc8a359ed<h3>B-36 A-1A Bomb Release Computer</h3>
<p>This is a very rare item.
It's part of the bombing navigation and control system for the
<a href="http://en.wikipedia.org/wiki/B-36">B-36 peacekeeper bomber</a>.</p>
<p>I can find references to the A-1A, but little detail. Here's one reference:</p>
<blockquote><p>The bombing-navigation system incorporating the Y-3 periscope and the A-1A computer,
dubbed the K-3A, came to be the standard system for B-36 aircraft and early production model B-52's.</p>
</blockquote>
<p>Another is:</p>
<blockquote><p>During later modernization programs, the K-1 system was replaced by the much more reliable K-3A system.
This included the Farrand Y-3 periscope bombsight, an A-1A improved bombing/navigation computer,
and an improved version of the Western Electric AN/APS-23 radar.
The Sperry A-1A bombing computer could be used between altitudes of 4700 and 50,000 feet, at grounds speeds between zero and 760 knots.</p>
</blockquote>
<p>Note that the Y-3 periscope sight is closely related to the Y-4 periscope sight <a href="../y4_bombsight">that we have</a>.</p>
Misc AEC Analog Computer2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:57c4545b-d07f-3b66-bce8-e12ff4ed3020<h3>Misc AEC Analog Computer</h3>
Analog Plugin Module2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:4084a152-d154-321f-8811-53c9eabcee00<h3>Analog Plugin Module</h3>
B-57 AN/ANS-7 Navigation Computer2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:01493c35-b09b-3437-8546-7a723eefc33a<h3>B-57 AN/ANS-7 Navigation Computer</h3>
<p>This is a navigation computer used in the <a href="http://en.wikipedia.org/wiki/RB-57">RB-57</a>,
the <a href="http://en.wikipedia.org/wiki/C-135">C-135</a>,
the <a href="http://en.wikipedia.org/wiki/F-100_Super_Sabre">F-100</a>,
and the <a href="http://en.wikipedia.org/wiki/RF-101">RF-101</a>.</p>
<p>(<a href="http://www.designation-systems.net/usmilav/electronics.html#_JETDS_AN_Listings">Here</a>
is a site summarizing the U.S. military equipment
designations, such as AN/ANS-7).</p>
<p>The ANS-7 first flew in the late 1950's. It was made by the Ford Instrument Co. (not affiliated with Ford
motor companies).
At the time Ford was one of the premier manufacturers
of electro-mechanical analog computers, including the most impressive
monster: the Mark I, which weighed over 3,000 lbs. (More on the Mark I
below).</p>
<p>Figure 2 is a closeup of two of the three disk integrators (as described in
the intro to this page) contained within the ANS-7.</p>
APA-16 Radar Bombsight Control2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:f88f049d-2679-325a-b821-0dbc0581c40c<h3>APA-16 Radar Bombsight Control</h3>
<p>This appears to be the control console for an AN/APA-16 radar bombsight.
It was used in the World War II era <a href="http://en.wikipedia.org/wiki/Consolidated_PBY_Catalina">PBY-6 patrol bomber</a>.</p>
APA44 Range Computer2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:79b57eef-1416-369f-b2d6-9e9fcd7c5b83<h3>APA44 Range Computer</h3>
<p>I don't know much about this device other than the AN description:</p>
<blockquote><p>AN/APA-44: Ground Position Indicator System;
manufactured by Bell Telephone Lab.; used with AN/ASB-3 and AN/APS-23/27/31; used in B-45 (together with AN/APS-23 to form AN/APQ-24), RB-66</p>
</blockquote>
<p>where ASB-3 is:</p>
<blockquote><p>AN/ASB-3: Bomb Directing Set; manufactured by Bell Telephone Lab.; used AN/APA-44, AN/APS-23</p>
</blockquote>
<p>and the APS- devices are search radars. And:</p>
<blockquote><p>AN/APQ-24: K-1 Radar Navigation & Bombing System; used in B-36B, B-45A, B-50, B-66B</p>
</blockquote>
<p>The fact that this device was used on the <a href="http://en.wikipedia.org/wiki/North_American_B-45_Tornado">B-45 Tornado bomber</a> is interesting.
The B-45 was U.S.'s first jet powered bomber and the first with in-air refueling.
It looked suspiciously like a World War II bomber with jet engines instead of propellers.
For example, the wings were staright instead of swept back.</p>
<p>The B-45 is not well known today since it was limited in many areas and was fairly quickly replaced by the
<a href="http://en.wikipedia.org/wiki/Boeing_B-47_Stratojet">B-47 Stratojet bomber</a>,
the first bomber with a modern jet-based design.
There were only 143 B-45's produced and they entered service in 1948 and by the early 1950's,
most had been converted to reconnaissance versions, the RB-45.</p>
B-36 AN/APA-59 Navigation Computer2010-07-26T00:00:00ZG. Glenn Henryurn:uuid:88cac9df-b028-3f71-8f7e-5547bd2ecb97<h3>B-36 AN/APA-59 Navigation Computer</h3>
<p>This is part of a complex of devices that integrated navigation, radar, and bombing functions for the
giant 10-engine <a href="http://en.wikipedia.org/wiki/B-36_bomber">B-36 bomber</a>.
We have two components: the APA-59 navigation computer shown here and the <a href="../a1a/">A-1A bombing computer</a>.</p>
<p>Figure 4 is a picture of the navigator/bombardiers station in the B-36 showing a very recognizable APA-59 (outlined in red) just beyond the bombsight periscope.</p>