Hi Everyone,
I'm making some good progress with the Philips P800 minicomputers. I'm
anxious to get an operating system running on them, and lack of
working disk drives (I haven't been able to get one of the X1215
cartridge disc drives going yet), has pushed me in a somewhat
different direction. I found an image of an X1215 disk pack containing
a DOS version 5 installation on Theo Engel's website. I have
implemented a very basic X1215 emulator in an FPGA PCIe card. Together
with a small piece of software, and a cable with the necessary level
converters, the emulator presents the X1215 disk images to the disk
controller in the P800. The software is responsible for loading the
image into the FPGA's memory buffer one track at a time.
This now works to the point where the initial part of the IPL works
correctly. Four sectors are read from disk, after which the P800
displays a "MONITOR?" prompt. After typing "DOM", there is another
flurry of disk activity, then nothing. No "** DOS 05 **" banner. I
noticed that the disk emulator never asks for anything other than
track 0, so there is probably an error in the implementation of the
SEEK command.
To be continued...
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