4MB STM RAM upgrade in 1040 STF?

[pixelpusher]

After installing Exxos' 4MB expansion (https://www.exxosforum.co.uk/atari/last/4mb/index.htm), which I had laying around for an embarrassing long time (the - non destructive - unsoldering job, was as time consuming as I imagined ) I looked at another 1040 STF of mine which has the early motherboard (viewtopic.php?f=52&t=6458) and wondered, if it would be possible to make the STM 4 MB upgrade from Exxos' store (the one base on agranlund's open soure contribution) work.

Does anyone know or has tried (if it fits and works)? The question has been asked about two years ago (viewtopic.php?p=88544#p88544) but nobody followed up, as far as I can see.

[rubber_jonnie]

Do you mean this one: RAM Expansion?

Should work fine.

[pixelpusher]

Do you mean this one: RAM Expansion?

Should work fine.

Yup #240 in the store. Thx rubber_jonnie!

[rubber_jonnie]

Do you mean this one: RAM Expansion?

Should work fine.

Yup #240 in the store. Thx rubber_jonnie!

What I would say is be very careful about installing the headers. Another user put some in the incorrect location and had issues, so just read the instructions fully.

[pixelpusher]

Yup #240 in the store. Thx rubber_jonnie!

What I would say is be very careful about installing the headers. Another user put some in the incorrect location and had issues, so just read the instructions fully.

Just to follow-up on this: I received the 4 MB expansion (faster than expected - thx exxos!); while it might work in the 1040, it definitely won't fit.

The spacing of the RAM chips in the 1040 is much wider than on the 520, so I would have to solder flying wires (which a colleague of mine had originally done for me - to extend the 1040 to 2.5 MB - with the machine at the end of the 80s, but started getting unreliable at some point) instead of the solid headers.

Guess I would have to learn to use KiCad - and find a source for the components (esp. the RAM chips - does anyone know where to get them?)...

[rubber_jonnie]

What I would say is be very careful about installing the headers. Another user put some in the incorrect location and had issues, so just read the instructions fully.

Just to follow-up on this: I received the 4 MB expansion (faster than expected - thx exxos!); while it might work in the 1040, it definitely won't fit.

The spacing of the RAM chips in the 1040 is much wider than on the 520, so I would have to solder flying wires (which a colleague of mine had originally done for me - to extend the 1040 to 2.5 MB - with the machine at the end of the 80s, but started getting unreliable at some point) instead of the solid headers.

Guess I would have to learn to use KiCad - and find a source for the components (esp. the RAM chips - does anyone know where to get them?)...

Do you have a photo? I'm surprised that the spacing is different so some sort of reference would be useful.

[pixelpusher]

Just to follow-up on this: I received the 4 MB expansion (faster than expected - thx exxos!); while it might work in the 1040, it definitely won't fit.

The spacing of the RAM chips in the 1040 is much wider than on the 520, so I would have to solder flying wires (which a colleague of mine had originally done for me - to extend the 1040 to 2.5 MB - with the machine at the end of the 80s, but started getting unreliable at some point) instead of the solid headers.

Guess I would have to learn to use KiCad - and find a source for the components (esp. the RAM chips - does anyone know where to get them?)...

Do you have a photo? I'm surprised that the spacing is different so some sort of reference would be useful.

Sure - note that the board starts on the left side with its pin holes directly over the DRAM chip (camera distorts a bit being held so close)

IMG_4514.jpeg (418.38 KiB) Viewed 539 times

(the wires from the home made extension are still there, so it looks a bit wild atm ), the expansion being about 2cm shorter than this (C070523-001 REV D) board revision would need.

[rubber_jonnie]

First thing I'd mention is that the board does not have the notches of the silkscreen lined up with the notches in the RAM chips, so can you flip it 180 degrees and take another pic please and also one of just the mainboard for reference, thanks.

[pixelpusher]

First thing I'd mention is that the board does not have the notches of the silkscreen lined up with the notches in the RAM chips, so can you flip it 180 degrees and take another pic please and also one of just the mainboard for reference, thanks.

I'm fully aware of that (and did that to not cover the one dram with the two full rows of pins on the expansion board) - and even if turned by 180 degrees, it would still not cover the last chip on the right (or the one left of it that's barely covered)...

I'll add screenshots when back from work...

[rubber_jonnie]

First thing I'd mention is that the board does not have the notches of the silkscreen lined up with the notches in the RAM chips, so can you flip it 180 degrees and take another pic please and also one of just the mainboard for reference, thanks.

I'm fully aware of that (and did that to not cover the one dram with the two full rows of pins on the expansion board) - and even if turned by 180 degrees, it would still not cover the last chip on the right (or the one left of it that's barely covered)...

I'll add screenshots when back from work...

I'm not saying it would fit but just that seeing it in the correct context is useful, and also seeing the bare board too.

I'm very image based, so not a dig, I just need to see things