Cable or Pinout for NEC PC-8001mkII

HxC Floppy emulator support for all others computers...
Post Reply
cjs
Posts: 5
Joined: Sun Sep 08, 2019 8:34 am

Cable or Pinout for NEC PC-8001mkII

Post by cjs »

I have a NEC PC-8001mkII computer (sometimes incorrectly called a "PC-8001mk2") which has a built-in disk controller for PC-8000-series double-density 5.25" drives. (The English and Japanese Wikipedia pages contain a bit of information about this model.)

The floppy disk connector on the back is a female 36-pin micro-ribbon connector, also known as a "Centronics" connector, similar to printer and SCSI drive connectors from the 1980s. That Wikipedia link shows the male and female connectors, and a picture of the female connector on the computer is attached to this post.

Unfortunately, I have so far been unable to find a pinout for that connector. Given the number of pins, I'm guessing that it's moderately likely that they're directly running Shugart's 34-pin SA-400 interface through that connector. I have an oscilloscope; if you have suggestions for me about how to reverse-engineer the interface I'll happily take them.

I'd like to use an HxC Floppy Emulator with this machine, both for N-BASIC and to run CP/M. So I have the following questions:
  1. Does anybody know what the pinout would be for the 36-pin micro-ribbon connector, or know anybody who makes/sells cables for it? (I'd prefer to make my own cable, as I have the parts for this, but I can buy one to reverse-engineer the pinout if that's absolutely necessary.)
  2. Has anybody already used an HxC with this or any other PC-8001-series machine?
  3. Is the disk format the same as the PC-8801 and/or PC-6601, both of which are on the HxC supported computers list? (The PC-8801 was the 16-bit series that followed on from the PC-8001 series, and the PC-6601 series was similar to the PC-8001 series but cheaper and with arguably better graphics.)
Attachments
NEC_PC-8001mkII_floppy-disk-interface.jpg
NEC_PC-8001mkII_floppy-disk-interface.jpg (76.51 KiB) Viewed 3629 times

Jeff
Site Admin
Posts: 7716
Joined: Fri Oct 20, 2006 12:12 am
Location: Paris
Contact:

Re: Cable or Pinout for NEC PC-8001mkII

Post by Jeff »

Have you the external floppy unit ? If so you can find the pinout from the internal floppy drive pinout which is probably standard ?

cjs
Posts: 5
Joined: Sun Sep 08, 2019 8:34 am

Re: Cable or Pinout for NEC PC-8001mkII

Post by cjs »

Jeff wrote:
Tue Sep 10, 2019 7:41 am
Have you the external floppy unit?
No, sadly, I do not.

Jeff
Site Admin
Posts: 7716
Joined: Fri Oct 20, 2006 12:12 am
Location: Paris
Contact:

Re: Cable or Pinout for NEC PC-8001mkII

Post by Jeff »

cjs wrote:
Tue Sep 10, 2019 4:17 pm
Jeff wrote:
Tue Sep 10, 2019 7:41 am
Have you the external floppy unit?
No, sadly, I do not.
Any schematic / Service manual ?

cjs
Posts: 5
Joined: Sun Sep 08, 2019 8:34 am

Re: Cable or Pinout for NEC PC-8001mkII

Post by cjs »

Jeff wrote:
Wed Sep 11, 2019 10:24 pm
Any schematic / Service manual ?
I have been unable to find one. If anybody comes across one (in English or Japanese), I'd love to have a copy.

It's looking as if I'll have to sit down with a 'scope and work it out for myself.

cjs
Posts: 5
Joined: Sun Sep 08, 2019 8:34 am

Re: Cable or Pinout for NEC PC-8001mkII

Post by cjs »

Just in case anybody's coming across this on a web search, this is not anything suitable for the HxC. That port turns out to be a parallel interface (8 data lines in each direction and some further control lines) that talks with a CPU or microcontroller in the disk drive unit using a high-level protocol (with messages like, "Here's data for track 3 sector 7; go write it."), similar to how the Commodore interfaces work. So while an HxC or two could be put in the external drive box, all the other electronics in that box are what's necessary to connect it to a PC-8001 system.

Post Reply