kodak80 H4 build (x2)

[exxos]

Cool. Only just fits!

[kodak80]

Board 3 SIMM with fix done on top.

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[kodak80]

I was thinking to try EmuTOS on one of my boards but I have no idea how to convert the IMG to work in a 27C4096 ROM chip. The plan was to replace TOS 1.02 in the dual boot ROM chip.

I have downloaded the 192kb EmuTOS IMG file but when I open it in my ROM programmer the bytes look to be swapped around. The first 2 bytes appear as 2E60 instead of 602E and the second 2 bytes show as 0401 instead of 0104 so I am guessing I need to somehow swap these around for programming a chip?

I have used PP's ROMSPLIT tool when programming for old ST computers with multiple ROM chips but as the H4 has a single 4mb chip, I am not sure I can use this tool.

Some guidance would be appreciated please.

EDIT: I think I have the answer. Using Hex Workshop, I can flip the bytes around and the output looks correct now in my programmer so now need to load this into a chip to test.

[exxos]

Yeah hex workshop or there's another one I can't remember currently, they have 16bit byte swap option.

[kodak80]

Okay, programmed HN27C4096G chip is working as dual boot TOS 1.04/EmuTOS 0.9.12.

Some initial shots on my H4:

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Interestingly the RTC date is way out under EmuTOS showing 1990. I checked with the FMC II software and the year was still set to 120 so I guess EmuTOS is managing dates differently to original TOS. Will do some reading on this.

EDIT: Date is resolved now and shows correctly under EmuTOS if I remove the DALLRTC.PRG from the AUTO folder and just run the AUTOFMC.PRG

[PaulJ]

@kodak80 , looks like a job for xboot so you can have differient startup steps for EmuTOS/TOS1.04.

[kodak80]

Okay back to the DMA H4 Buffer fix PCB. I now have one assembled and ready to test. Can someone confirm where the PAD1 on the fix PCB connects to on the H4 board? Does it connect to the 1.44mb GAL socket pin 7 (as per @Icky inverted IC bodge)?

FCAE8892-CB4C-4B96-85DA-109ADAB60E43.jpeg

[exxos]

It goes to FDCS on the DMA.

[kodak80]

It goes to FDCS on the DMA.

Thanks for confirming. Pin 7 on the 1.44mb GAL is labelled as FDCS in the schematic so this looks as good a place as any to connect to. Will give it a go. :D

[kodak80]

Okay have the DMA Buffer fix PCB installed and PAD1 is connected to pin 7 (FDCS) on the 1.44mb GAL socket.

I have EmuTOS running, my SatanDisk in and powered from 12v on one of the 4 pin power headers. SatanDisk works and floppy both work fine with the IC6 jumpers in place prior to testing this fix PCB.

Initial testing and I get weird non-consistent responses from floppy and no response from SatanDisk. Floppy seems to randomly work after reset. Sometimes shows A: and B: desktop icons, sometimes A: or B: no C: drive ever shows.

With TOS 1.04 the initial splash screen show Drives: 0 and then no desktop icons are shown.

EDIT: I have double-checked my soldering on the fix PCB and everything looks fine but the fix PCB stops both floppy and SatanDisk working when installed in my H4.