8870 Adventures

© Joe Farr, 2011 – 2023

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  • DAP4

    The DAP4 was probably one of the most popular of the VDUs that were connected to the 8870/Quattro machine. It had an inbuilt smudge grill guard on the front that can be be easily removed on the later version of the case; put your finger nails between the light grey and the dark grey frame […]

  • DAP4 VDU processor board

    The above is a 1528-01 DAP4 VDU processor board with 16K of RAM. I’ve highlighted the main sections of interest. I’ve currently no actual Nixdorf technical information relating to the 1528-0x DAP4 CPU, but what I’ve been able to figure out is here. The DAP4 was in service for quite some time, and was used […]

  • Cables

    It’s a sad fact that when an 8870 is removed the animals in charge usually just cut through all the cables. I’ve seen keyboard cables cut because they couldn’t figure out how to removed a SAS connector – it ain’t rocket science. Anyway, I’ll list here all the information I can find and figure-out on […]

  • Communication interface personality boards

    There are many different ways to connect an 8870 to it’s VDUs, printers and the outside world in general. The 8870 supports PLC (Programmable Line Controller) devices that provide a lot of interface options and protocols but for general connectivity of VDUs and modems, the ALME (Asynchronous Line Multiplexer Extended) is the preferred and easiest […]

  • 8251 Datasheet

    The 8251 is a Programmable Communication Interface controller and is found inside a DAP4 CPU board 1528-xx and form the interface between the CPU board electronics and the external personality interface board.

  • TC550 Memory Datasheet

    The TC550 is a 256 word by 4 bit memory and two of these memories are usually found inside a DAP4 CPU board 1528-xx. They are extremely low power CMOS memories and as such are used as NVR (None-Volatile RAM) by the CPU board to store user changeable configuration data.