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Glenn’s Computer Museum

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Figure 1: IBM 2870 Control Panel
Figure 2: IBM 2870 Control Panel

IBM 2870 Control Panel

As mentioned elsewhere, the IBM System/360 family had a new and powerful type of I/O attachment: the IBM channel. The channel comprised a programmable I/O controller and standard physical attachments to a wide variety of I/O devices. There were two basic type of channel controllers: A selector channel, and a multiplexor channel.

The IBM 2870 was the multiplexor control unit for the System/360 family. Figure 1 is the control panel from an 2870 controller. (The wooden frame is an add-on for displaying the panel.) Figure 2 is a page from the 2870 manual showing this control panel. Careful study of the control and status indicators shows that the 2870 was effectively a programmable computer.