Remarks about Cyber 180 I4 1CQH board - Display Controller
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Some important general features of Cyber 180 I4 IOU:
- T1 is the 20 MHz base clock, ~ 10 nsec pulse
- I4 has 4 barrels of 5 PPs each, 250 nsec (x4)
   "PP cycle time" (4 MHz)

On DSC schematics:
- the schematics symbols follow the IEEE standard
- I4 boards are based upon the Motorola 10k ECL family
   of SSI/MSI integrated circuits
- the 10192 driver essentially is a 16 mA current sink
- the analog output stage therefore is a 3-bit DAC
   with complementary analog output, 0.25 V/bit