Marconi 2828A Digital Simulator
 

I've just got a couple of bits of test gear made by Marconi instruments, I'll start separate threads about them to avoid confusion.

The first is a 2828A digital simulator. I think it's a test data generator for digital telephone systems.

Physically it's a 2U rack unit with a number of plug-in PCBs going in from the top, along with a linear PSU. The boards are interconnected by the edge connectors and there are also ribbon cables ending in DIL plugs that connect some of the boards to each other and to the front panel controls.

Most of the ICs seem to be 4000 series CMOS, there is also an 8085 processor with EPROMs and a RAM/IO chip along with something that I think is a ULA on one of the boards.

Does anyone know anything about this unit? Google has turned up nothing.