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.