1970- This is a rare 1970s IBM Computer Engineer’s Control Panel to diagnose problems with the System 370’s 3803-2 Data Channel Control Unit (for Tape, Disk and Peripheral hardware data exchange to mainframe).The IBM 3803/3420 Magnetic Tape Subsystem combines the capabilities of the IBM 3803 Control Unit and the IBM 3420 Magnetic Tape Unit to provide a wide range of data rate capabilities for those systems requiring 10½-inch reel compatibilityAt 6,250 bytes per inch (BPI) recording density, the 3420 Models 4, 6 and 8 have a nominal data rate of 470, 780 and 1,250KB/second, respectively. The Models 4, 6 and 8 can optionally read and write data at 1,600 BPI. The standard recording density for the 3420 Models 3, 5 and 7 is 1,600 BPI with optional 800, 556 and 200 BPI capability.
One 3803 Control Unit can provide access to as many as eight tape units. Sixteen 3420 tape units can be accessed through two, three or four control units.