4MB STFM RAM SIMM ADAPTER REVISED

Upgrade your RAM from ST to Falcon.
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exxos
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Re: 4MB STFM RAM SIMM ADAPTER REVISED

Post by exxos » Fri May 31, 2019 10:45 am

I've never tried tos102 with 4mb, I don't even know if 4mb works with 102 unless someone else has tried it ?

PSU OK ?

Possible bad soldering or broken track on the upper RAS CAS lines..
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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krisfeigl
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Re: 4MB STFM RAM SIMM ADAPTER REVISED

Post by krisfeigl » Fri May 31, 2019 2:16 pm

I am more concerned about damage to the MMU.

Its strange that it worked long enough for my floppy to be detected and sysinfo to run. Luckily I took a photo to show a friend within a few seconds and then I exited sysinfo to run the ram test tos file. It was during the ram test that it seemed to stop and then corrupt gfx appeared on the screen. The machine had locked up and from that moment on after turning the machine off and back on again all it would ever see was the 1024K of ram.

It was as if excess current had caused something to burn out in the about 60 to no more than 90 seconds of operation.

I checked all 35 solder joints I think with a monocle twice before powering the board up last night. I have taken photos of the top side of the board b4 I soldered the 4mb board on top of it just in case but cannot see any problems.

Could it be an issue with the MMU on pin66now?
Is this the 1st of these mods that you have had tried on the surface mount MMU?
Is the sfc mount MMU the same electronically as its larger brother but simply a different package?
I really want 4MB of ram. What exactly does placing that jumper across those vias do that could cause this issue?

I will try and resolder the link to pin66 on mmu just to be sure and I assume you suggest that I try and install at least the rom switcher now and boot with TOS 1.04

thanks for your help.

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Re: 4MB STFM RAM SIMM ADAPTER REVISED

Post by stephen_usher » Fri May 31, 2019 2:17 pm

Mega 4STs existed before Rainbow TOS was released, so it should work, surely?
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: 4MB STFM RAM SIMM ADAPTER REVISED

Post by exxos » Fri May 31, 2019 2:29 pm

krisfeigl wrote:
Fri May 31, 2019 2:16 pm
Its strange that it worked long enough for my floppy to be detected and sysinfo to run. Luckily I took a photo to show a friend within a few seconds and then I exited sysinfo to run the ram test tos file. It was during the ram test that it seemed to stop and then corrupt gfx appeared on the screen. The machine had locked up and from that moment on after turning the machine off and back on again all it would ever see was the 1024K of ram.
It does sound like you have a bad connection somewhere..

krisfeigl wrote:
Fri May 31, 2019 2:16 pm
It was as if excess current had caused something to burn out in the about 60 to no more than 90 seconds of operation.
This sounds more like a power supply issue, you need to have them recaped at least.
krisfeigl wrote:
Fri May 31, 2019 2:16 pm
I checked all 35 solder joints I think with a monocle twice before powering the board up last night. I have taken photos of the top side of the board b4 I soldered the 4mb board on top of it just in case but cannot see any problems.
Just because you do not see any problems, it does not mean that they are not there.. I would suggest adding flux to your solder joints and heating them up to reflow the solder anyway.
krisfeigl wrote:
Fri May 31, 2019 2:16 pm
Could it be an issue with the MMU on pin66now?
Other than a bad solder joint I do not see what else it could be.. Unless the MMU is faulty, but its unlikely.
krisfeigl wrote:
Fri May 31, 2019 2:16 pm
Is this the 1st of these mods that you have had tried on the surface mount MMU?
No. Lots of people over the years have used the SMT MMU with 4MB. My remake board has even been tried with a SMT MMU running 4MB a few weeks ago in fact.
krisfeigl wrote:
Fri May 31, 2019 2:16 pm
Is the sfc mount MMU the same electronically as its larger brother but simply a different package?
Its the same chip, but SMT package, and different pinout than PLCC.
krisfeigl wrote:
Fri May 31, 2019 2:16 pm
I really want 4MB of ram. What exactly does placing that jumper across those vias do that could cause this issue?
The jumper connects the 4MB wire from the MMU to the DRAM. It is to allow people to fit a switch to switch between 1MB and 4MB RAM.
krisfeigl wrote:
Fri May 31, 2019 2:16 pm
I will try and resolder the link to pin66 on mmu just to be sure and I assume you suggest that I try and install at least the rom switcher now and boot with TOS 1.04
As mentioned above by steve, TOS102 should be good with 4MB. Though I really would update to TOS104 anyway.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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Re: 4MB STFM RAM SIMM ADAPTER REVISED

Post by krisfeigl » Thu Jun 20, 2019 2:00 pm

Hi Guys

Thought I should update what transpired.

I changed PSUs. No change. Then I resoldered and refluxed all joints on bottom of board. No change. To be sure I also replaced r71 r72 and r73 with 68 ohm resistors too. Then I had the bright idea of shortening the yellow kynar MMU wire as I was worried it had introduced a delay being overly long. And hey presto that seemed to fix the problem so it was MMU related.

I have subsequently moved on to the next step, soldering in my 1st PLCC socket for the BLITTER chip using EXXOS prebuilt Crazy socket.
I rebooted the board after I cleaned up properly WITHOUT installing the BLITTER just to be sure no harm and all was well.

Bad news is I then installed the 2.3 accelerator and its matching TOS 1.04/2.06 board. The board booted straight away into TOS1.04 and i got to desktop. I was then able to run sysinfo but it showed the system was running at 8mhz and not 16 as I expected. Just as I noticed that the screen flickered and up came 4 to 8 bombs. The machine then blackscreened and reset and GEM desktop never appeared again. All I get are bombs at startup POST. I have tried resoldering the 16mhz wire and the TOS board link wire with no change. I did add the 8mhz select wire to earth to see if that would help but I was unclear as to whether I was to leave the 16mhz wire connected as well???

Tomorrow I will go back to this and put back my original 68000 back in its socket but I wanted to know what do I do with the TOS board. I will set it for TOS1.04 of course but will it work without the 2.3 accelerator and its wire in place?

Are these new issues i am having related to my surface mount mmu board being different timing wise from the standard board you designed this 2.3 accelerator on or have you had people use my board revision before? I know it MIGHT be PSU related but I do have a spare I could use but both are from 30 yr old STFMs and not new beefed up PSUs.

I know I should move this topic to the accelerator section too EXXOS so I will post any photos etc and continue this topic there

Thanks again for your help with this project. Its been INTERESTING to say the least ;-)

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Re: 4MB STFM RAM SIMM ADAPTER REVISED

Post by exxos » Thu Jun 20, 2019 2:06 pm

The booster defaults to 16MHz.. I assume you had the 16MHz wire connected to it ? Otherwise it will default to 8MHz regardless of 8/16MHz wire selection..

But yes, you should probably open a new thread in hardware issues, or start you own blog on all this :) It does sound like you are trying to do to much at once which will make things harder to diagnose.

EDIT: BTW I don't know about sys info, but if you are looking at that for speed results, it likely won't recognise the booster. You should use GB6 for such speed testings.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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