kodak80 blog

[kodak80]

First post for my blog. So something simple. I decided to take a 520STFM C070789-001 REV F board and update it to 1mb RAM and also use sockets as I had 2 sets of RAM chips removed from donor boards for my H4s which needed testing.

I followed Exxos guide here: https://www.exxosforum.co.uk/atari/last/ram/index.htm

Capacitors and resistors also came from the donor boards.

I was surprised to find that with the capacitors and the 3 missing resistors added that the board still booted up with empty sockets in bank 2.

Process was:
Add sockets and test board boots. Booted fine.

1.sockets soldered in.jpg (127.3 KiB) Viewed 6902 times

Add capacitors and test board still boots. Booted fine.

2.caps added.jpg (164.3 KiB) Viewed 6902 times

Add resistors and......test board still boots. Booted fine.

3.resistors added.jpg (104.48 KiB) Viewed 6902 times

4.boot working.jpg (35.63 KiB) Viewed 6902 times

Finally, insert RAM chips.....and....test board still boots

5.RAM chips inserted in sockets.jpg (157.88 KiB) Viewed 6902 times

1mb showing in Sysinfo

6.Sysinfo showing 1mb.jpg (89.65 KiB) Viewed 6902 times

Both sets of pulled RAM chips were tested and all working fine when tested with YART.

Very happy with the outcome.

[exxos]

[rubber_jonnie]

Good job sir

Gotta love these revision mainboards, very simple to work with.



Next dual TOS board

[JezC]

@kodak80 Great result!

I will have to try this on some of my 520 STFMs once I nominate the donor systems...yet more jobs to add to the ever-growing list...

[kodak80]

My PCBway order finally arrived and included these 32 pin to 28 pin ROM boards:

IMG_4918.jpg (241.27 KiB) Viewed 6787 times

I built a couple up and tested them with 27C010 chips with TOS 1.04 with IDE patch programmed in and tested them in one of my 2 chip STFMs:

IMG_4920s.JPG (383.19 KiB) Viewed 6787 times

These were so that I can test the programmed chips work. For the final solution, I was thinking to solder these PCBs into the Atari to effectively give me two 32 pin sockets but have not looked at the height given that the shielding will be very close to the front one.

So, happy that the PCBs and the ROM chips seem to work.

[kodak80]

I recently purchased a 520 STFM board from the UK and when it arrived, it was showing 11 bombs on boot with some corrupted graphic artifacts on the screen. The board is the same model and revision (C070789-001 REV F2) as the one I was testing the 2 chip adapter boards in.

All ICs on this board are soldered directly and there are no sockets apart from MMU and GLUE ICs.

There is no real information on the internet about what 11 bombs actually is in the 68000 CPU but the little information I found would say it is address bus or data bus related. The TOS on this board was 1.04 UK (2 chip) and as these are not as available as the 6 chip, I decided to remove these ICs and install some sockets. After installing the original ROMs back in the new sockets, the board was no worse than before so I had not damaged anything by soldering in the sockets.

I then swapped the TOS ROM ICs for the 32 pin PCB adapted ones I had created in the previous post. Hey presto, the board booted to the green desktop.


With further swapping of 1 ROM chip at a time, I confirmed the the front ROM (HI) was faulty. The original LO ROM chip was working fine.

Just sharing this information as the 11 bombs is now resolved for this board.

[JezC]

Nice work!

I'm still trying to find/make time to diagnose the faults on a few STFM boards so seeing these posts of positive results is very encouraging.

When I get round to ordering some PCB's I'll have to make sure to include some of your design in the order (if that's OK with you?) so that I can convert some of the 2 chip TOS 1.02 systems up to 1.04.

I'm also tempted to try and make a version to allow 2x images to be included with a switch to select the TOS image (so I can either boot 1.02 or 1.04 or maybe even choose 1.04 or 2.06/EmuTOS with the external decode for the additional memory space for v2.06 or larger EmuTOS images).

[kodak80]

As I have now tested these work. This is the Gerber for the 32 pin 27C010 adapter boards I used from my STFM 2 chip TOS. For anyone looking to get some made. Just keep in mind that sockets in the top of this make it sit too high for shielding to be fitted. It might work if soldered directly to the motherboard and have a 32 pin socket.

a51ca95b9e330dd9ace7ea63e2fa6130.png (13.78 KiB) Viewed 6710 times

STFM 32pin to 28pin TOS ROM adapter_gerber.zip

(18.6 KiB) Downloaded 256 times

[kodak80]

Nice work!

I'm still trying to find/make time to diagnose the faults on a few STFM boards so seeing these posts of positive results is very encouraging.

When I get round to ordering some PCB's I'll have to make sure to include some of your design in the order (if that's OK with you?) so that I can convert some of the 2 chip TOS 1.02 systems up to 1.04.

I'm also tempted to try and make a version to allow 2x images to be included with a switch to select the TOS image (so I can either boot 1.02 or 1.04 or maybe even choose 1.04 or 2.06/EmuTOS with the external decode for the additional memory space for v2.06 or larger EmuTOS images).

Yeah, something I would like to create also so that I could load the 256k EmuTOS into these 32 pin chips as an option but have no clue how the decode stuff works. At least I can now think about using an IDE board and drive in my older STFMs Just not sure the Exxos IDE board would fit in these model boards and have a keyboard in place.

[JezC]

Yeah, something I would like to create also so that I could load the 256k EmuTOS into these 32 pin chips as an option but have no clue how the decode stuff works. At least I can now think about using an IDE board and drive in my older STFMs Just not sure the Exxos IDE board would fit in these model boards and have a keyboard in place.

I think @rubber_jonnie and/or @PhilC might know where the decode info is (I thought I'd seen it but couldn't immediately find it just now) - they have both produced their own versions of some boards with the extra decoding logic included.

Thanks for posting the gerbers for your boards too!