First post, by RealityTech
So, This thing arrived the other day. I had one of these (PPC640 version) back in the day and ran a Bulletin board with it, there wasnt much else I could think of to do with it, it was limited and slow but DID have a fast (for the time) modem. Mine had a Stratum Sprint HD kit installed which made it even less portable but marginally more useful.
This was purchased as is, no gurantee at all. It fired up in Danish and went to a lone cursor and nothing else. Memory reminded me of the dip switches and re-enabling the internal CGA got it alive again. Now its working, but in Danish and theres a line out on the screen and it's in Danish still...
Memory once again jogged. A search suggested the only fix was to burn new ROMs but the PC1640 I had definateley had multi language support and this was supposedly the same BIOS. Some hunting found the very same links hidden behind the printer port. Using https://www.seasip.info/AmstradXT/ppctech/section1.html LK1 was cut and up it came in English. Wouldnt boot anything for toffee though. Popped in a 1.44Mb drive, removed said drive, set it to DS0 and tried again (The PPC uses drive selects). Formatted a 720 Freedos disk on a USB floppy and it booted!
I cleaned both original drives, B: came back, A: did not. in the interests of my sanity a GoTek was ordered and flashed with FlashFloppy and the non functioning A drive was removed. The sockets got fitted for the 640K upgrade and now I'm waiting on the chips.
So now I'm stuck, no HD, awful GFX and no real expansion. I remebered the expansion port and the Stratum and thought about re-building it. The unit used a realy fragile arrangement of a ribbon cable soldered to the expansion port and then a controller in the modem bay. I dont plan on fitting the modem so this void is empty. So first job, a daughter board to go from the connectors to the modem board. A day of fussing to get it to my liking and off it went to PCBWay...
This brings the ISA bus into the modem bay and adds the buffers and pullups needed. This wouldnt support a DMA capable device at this moment as the address buffers are one way. The pin header in the modem bay is PC104 compliant right down to the mounting holes so at this point with mo more work adding upgrades is possible, there are PC104 flash controllers, VGA cards that *should* work here. It wil also hapilly mate to the connectors externally for testing purposes as this is probobly a rather one way mod. I may change the mating with the connectors to a flex PCB but this isnt cheap.
So the plan...
Once the PCB arrives and I've tested it works as expected I plan on taking the XTMax design and making it fit in that modem bay. This gives me more RAM and a hard drive. I want to see if I can generate the select lines I need from the Teensy to drive a UART and from there an ESP8266/32 for Serial based networking. I also want to add an OPL3 in Adlib mode. I want the Adlib to passthrough the speaker so no external speakers are needed. I may also add support for LiOn batteries. As the official docs say the expansion should provide power, I'm hoping the move to modern regulators will reduce it's power thirst.
Once that works, well there are two other things I may look at. The Realtek 8bit single chip VGA would be the next logical step. Potentially an proper NIC of some kind.
This isnt a good example and the LCD is bad, so thats on the hit list too, especially if I can get VGA support in here. Ideally I want to push this little thing as far as I can just because