• Please review our updated Terms and Rules here

Amstrad PPC512 / 640 ISA Expansion Board Design

Wow! I'm trying to repair the internal hd board (the one plugged in the copro socket) since weeks... I will pass to this great external solution!
 
aotta said:
Wow! I'm trying to repair the internal hd board (the one plugged in the copro socket) since weeks... I will pass to this great external solution!
Click to expand...

You've got an HDD board that plugs into the coprocessor socket? If you're able to make pictures and/or ROM dumps I'd be interested to see them.
 
Yes, i've dumped the roms and made some shots. The Rom contains the hd driver on top, then the ROS 2.1 from &H4000, and it's splitted in 2 27C128 eprom.
The power circuit doesn't work anymore (i had a shorts while testing) but it was only for the +12v and +5v to the special power connector of its 20mb hd.
There's no PAL/GAL on the board, only 74hcXX and the ROM:

ICs.jpg
front_A.jpg

back_a.jpg
 

Attachments

  • ICs.jpg
    ICs.jpg
    195.4 KB · Views: 1
  • front_A.jpg
    front_A.jpg
    114.7 KB · Views: 1
Interesting ROMs. It looks as if the first 16k is the hard drive BIOS, and the second 16k is the PPC system BIOS, so they replace the PPC's own ROMs entirely.

The drive geometry is hard coded rather than any attempt being made to probe it from the drive.

There are two entry points, at offsets 6 (format hard drive) and 9 (set timeout for spin-down). The timeout appears to be stored in bytes 3Eh / 3Fh of CMOS memory.

The hard drive itself is a memory-mapped device at segment 0F000h. It looks to me as if it's ATA, with the registers at offsets 0,2,4,6,8,... within that segment. There's also an access at offset 1Ch which may be connected with the spin-down.

The copyright message is 'Controller Copyright (c) 1989 Bineco'
 
Thank you JohnElliott for the info! but i don't think the ROS mapped in the half ROM is a replacement of the original ROS, and i made a test (when the HDIC worked!) and, without the 40107 / 40108 Roms, the PCC didn't start.
I think that, in some way, the memory address is shared from the co-proc lines and the ROM/RAM. Now that the interface is not working, i can't see the ROM at expected C800 location, but noticed some bits differences at F000 when card is mounted. So, probably the roms copied the ROS to make consistence to reading at ROS addresses.
But i'm not at all at expert in 8086's machines, so are only my thoughts....
 
Well, i got today the 74hcxx logic ICs and... HDIC 88 is working again! now, since the anonimous original 20mb hd makes strange rumours (and i'd like to replace it with a CD or SD to IDE solution), i'll try to replace the original roms with the Universal XT Bios ones!
 
Oh coming very very soon :) with kicad files uploaded to github too.
XTIDE/512K RAM upgrade, LAN and adlib. The connecting bridge board not shown.
Boards should be with me next week.
 

Attachments

  • 20211107_201148.jpg
    20211107_201148.jpg
    119.2 KB · Views: 8
  • 20211108_133232.jpg
    20211108_133232.jpg
    124.6 KB · Views: 7
Yea, so with this I designed the PCB so that it can be mounted externally or internal and has the same dimensions as the internal modem. Then there is a bridge board that goes from the ports to the card if mounted internally. I went with Blue PCB for initial run.
 

Attachments

  • 20211109_130526.jpg
    20211109_130526.jpg
    132.8 KB · Views: 15
  • 20211111_222920.jpg
    20211111_222920.jpg
    109.4 KB · Views: 14
That is a thing of beauty! Is this something other PPC users can enjoy? Because holy hand grenade Batman, I need one of those! It would be awesome to have a hard drive in the system.
 
Yes, thats my intent. So once tested, this will be available to build via github design files, or buy , I will have a small number initial run, and will be fully assembled, but will require soldering to install via the bridge board. I will know next week if I have messed up or not LOL.
 
Cool, I would love to buy one of these and review it for the article I’m doing on the PPC range of computer. I’m fine with through hole soldering but not so confident with SMD’s.

i think I might have spoke to you earlier on YouTube! Lol
 
no news about the PPC_internal_card? i noticed the githhub public repository is empty since last year, i'd like to make a similar card (with only xt-cf support) for my ppc-512, but it would be great starting from a tested gerber pcb, in particular for the "daughter" pick-up part....
Please @Theoryboy give us some news, and thank you in advance
 
You must log in or register to reply here.
Back
Top