exxos's Atari, Amiga & retro forum

Hi,

My setup includes a DFB1X with MAPROM.PRG for TTRam, HDUtils 12.53 and bluescsi.
I'm getting "Illegal Instruction" (4 bombs) error when MAPROM is active and I'm trying to read files off my bluescsi. If I disable MAPROM, everything is good.

Has anyone succeeded in using TTRam with a SCSI HD? There's a thread on flashing a 4.04 OS variation that might remove the need for MAPROM, but I'm not sure the issue is MAPROM, rather TTRam activation.

Just before any experts like exxos / badwolf chime in, can you load the latest EmuTOS 1.4 onto your flash-rom and try SCSI using that? I think that would be a worthwhile test. EmuTOS doesn't require MAPROM or any hard disk drivers. Since they added full true colour support to 1.4 I personally don't see any reason to be using standard Atari TOS anymore. You can simply double-click EmuTOS.PRG if you want to try EmuTOS without flashing it.

Are you using NVDI? That's a requirement.

Just a quick update that I flashed the TOS4DFB.IMG mentioned elsewhere as it does not require MAPROM.PRG, but now when accessing SCSI I get 11 bombs :-)

Will test next with EmuTOS 1.4 and report back.

I also just noticed at the bottom of the page: https://exxosforum.co.uk/atari/last/DFB1X/
"FIRMWARE V105 MODIFICATION"

Just wondering if you've got that. Not sure if this is related to your problem or not though.

whomper, I just noticed you're having many problems and most seem to be going unresolved (on the forum)

Your SCSI issues can be related to your clock patch issues here: viewtopic.php?p=130943#p130943

But you haven't made an update in that thread for quite a while. From what I remember there was an issue with your SDMA trace, and capacitor / resistors. I know you have now got a DFB1X and it's easy to just think this is the problem, but the Falcon is like a house of cards, you gotta stack everything on a stable base, otherwise you're gonna be chasing ghosts.

Steve wrote: 25 Jul 2025 10:32 whomper, I just noticed you're having many problems and most seem to be going unresolved (on the forum)

Your SCSI issues can be related to your clock patch issues here: viewtopic.php?p=130943#p130943

Indeed, I'm still working off the original clock patch, and have recently added a DFB1X, and the system seems stable apart from sound DMA, which I will tend to when receiving the missing resistors for the V4 patch installation.

Meanwhile, I noticed SCSI and TT Ram are not friends, so I'm wondering if others have managed to get them to work together. (There are a few threads on the topic related to HDDriver and this setup, but are non conclusive).

Steve wrote: 25 Jul 2025 08:23 I also just noticed at the bottom of the page: https://exxosforum.co.uk/atari/last/DFB1X/
"FIRMWARE V105 MODIFICATION"

It may seem that the only thing v1.05 adds to the mix is the ability to activate on board TOS when DFB1X is disabled, so might not add much here.

whomper wrote: 25 Jul 2025 10:53 Indeed, I'm still working off the original clock patch, and have recently added a DFB1X, and the system seems stable apart from sound DMA, which I will tend to when receiving the missing resistors for the V4 patch installation.

Meanwhile, I noticed SCSI and TT Ram are not friends, so I'm wondering if others have managed to get them to work together. (There are a few threads on the topic related to HDDriver and this setup, but are non conclusive).

So this is the answer to all your problems .. SCSI stability needs a clock patch, and to my knowledge DFB1X needs a clock patch for stable operation. In my opinion.

whomper wrote: 25 Jul 2025 10:53 Indeed, I'm still working off the original clock patch, and have recently added a DFB1X, and the system seems stable apart from sound DMA, which I will tend to when receiving the missing resistors for the V4 patch installation.

But the image you sent me last night shows no clock patch at all ?


Your not going to get anywhere trying to solve DMA issues until basic things are fixed first. If you cannot do the work yourself I suggest you find someone local who can do modifications for you. If you are not confident in them, then you could inherently make things a whole lot worse..

I also did not send you any resistors because you said you did not want to fit the leaded ones in case it ripped up the tracks ! So I never sent any!

I think you should just concentrate on one problem at a time because you have several threads open now, and it is becoming immensely confusing for everyone involved trying to figure out what you are and are not actually doing.

I think I have cured this issue, Installing Hddrutils' ALTRAMFIX.PRG in the AUTO folder as first app seems to cure the issue with SCSI. Objective is to setup a 64K buffer.

It did reduce bluescsi transfer rate from about 1,840 kb/sec to 1,740 sk/sec though