Disk Controller Breakdown

A project log for HP 4952A turned general purpose CP/M machine

Attempting to reverse engineer an HP 4952A into a general purpose z80 computer capable of running CP/M.

Trevor Johansen AaseTrevor Johansen Aase 12/31/2018 at 23:060 Comments

This is a simple little board. Exactly the same as in the 4951C so I have full schematics. This gave me the initial system bus J1 pinout.

Nothing interesting to note other than the fact that the entire card is essentially an SBC. Full 8088 processor with 32k RAM & ROM. The typical WDC floppy controller. There is a custom DMA controller and PIT interrupt generator.

The manual says that this board will load a disk transparently into memory. I assume they mean the "file" that contains the bus data only as there is not enough system ram.