digger wrote on 2026-09-07, 17:20:

Hi @FreddyV. Got it. IRQ3 only. […]
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FreddyV wrote on 2026-09-07, 16:09:

Hi @digger

For tandy 1000 EX, you should keep only the IRQ3 wired. Only 2,3,4

Picomem 2 multiplexed irq is still only on IRQ7

Hi @FreddyV. Got it. IRQ3 only.

What exactly do you mean with "Only 2,3,4"? Those can't be IRQs. Do you mean "remove jumpers 2, 3 and 4", since I should only have jumper 1 in place for IRQ 3?

I'm going to try it tonight and share my findings here.

Thanks!

Only 2,3,4 exist on the header, so only 3 is usable

Hi,
It detect IRQ5 as the tandy 1000 video use it...
So the picomem see it fired, but it is an error.
It will then try to use irq5 as picomem irq, but picomem 2 irq is hardcoded to irq5.

So, I have to mofify the firmwareto correct those things.

Once done, I should allow the emulated DMA to work at the same time as real dma.

Then, SB can work as well.

Picomem 1 has virtual dma working on the ex/hx.

You can also use mod master XT to use GUS. No need of dma/irq

FreddyV wrote on Yesterday, 14:54:

Hi, It detect IRQ5 as the tandy 1000 video use it... So the picomem see it fired, but it is an error. It will then try to use ir […]
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Hi,
It detect IRQ5 as the tandy 1000 video use it...
So the picomem see it fired, but it is an error.
It will then try to use irq5 as picomem irq, but picomem 2 irq is hardcoded to irq5.

So, I have to mofify the firmwareto correct those things.

That might explain the instabilities I was experiencing, especially when trying to use the PicoMEM 2 to increase the RAM on the machine. The test results of PICOMEM.EXE would sometimes fail, sometimes not, at some point I got random ASCII art filling the screen, sometimes I would have random lock-ups on the DOS prompt, and Monkey Island (the 16-color version) would always start up with a garbled screen and then quit with a heap corruption error. I would also get the garbled screen when forcing the game to run in CGA mode, just with only 4 colors of random pixels instead of 16.

Graphical applications that would work with 256KB or less ran fine, even with the PicoMEM 2 installed: Alley Cat with the Tandy patch and os8088.

Using only the PSRAM (and not the Pico's faster zero-waitstate RAM) for emulating all the RAM did appear to make the RAM tests of PICOMEM.EXE pass, but Monkey Island sill wouldn't run.

I also noticed the memory configuration in the PicoMEM 2 setup resetting or changing sometimes after a restart or power cycle.

Once done, I should allow the emulated DMA to work at the same time as real dma.

Then, SB can work as well.

Picomem 1 has virtual dma working on the ex/hx.

That would be pretty cool! Sound Blaster support on that machine would merely be a nice-to-have to me, since the on-board 3-voice synthesizer is the machine's charm, but it's still fun to play with.

I made some screenshots of the various PICOMEM.EXE test runs. Let me know if those are useful to share. Maybe I can have those results written to log files instead. Does PICOMEM.EXE have an option for that? Or maybe I can just redirect the output.

I'm currently running it with DR-DOS (SvarDOS), in case that matters.

Would it be possible to add Disney Sound Source (DSS) emulation to the PicoMEM 2, in addition to just Covox Speech Thing emulation? The Sound Source would be a period-correct sound device for this machine, which would compliment the 3-voice synthesizer well with buffered PCM output and some support in games that can run on PC/XT systems. And it requires neither IRQ nor DMA. You might be able to port the DSS emulation code from the Picovox firmware, which is based on the same microcontroller as the PicoMEM 2.

Happy to help with troubleshooting/debugging with any of this.

Thanks!