New ST owner seeking upgrade recommendations

[ParanoidLittleMan]

I made in past expansion with 30 pin SIMMs for Atari ST . Without board. It was just direct soldering of SIMMs to proper locations.

And as I see this is the plan here too .

So, if you want I can write you detailed connection plan - to say so.

For now the principle:  Surely must first deactivate existing RAM. That means to connect all involved RAS and CAS lines to +5V . Of course not part what leads to MMU chip, but what leads to RAM chips - there are 68 ohm resistors between.

 

Connections:  you have 4 modules with 8-8-8-8 data lines. There are  2  16 bit banks, what Atari ST MMU chip can control, access .  Each bank has 3 control lines - CAS0H, CAS0L, RAS0       and CAS1H, CAS1L, RAS1 .

All address lines and write line go parallel to all RAM chips - in this case modules.   You need to connect 16 data lines to data lines of modules.  That needs some care.

There are Low and High data lines (bits in fact), and they need to be connected to modules like:

8 High data lines (D8-D15) to module what gets CAS0H  and to module what gets CAS1H .

8 Low data lines (D0-D7) to module what gets CAS0L  and to module what gets CAS1L .

RAS0 goes to modules where go CAS0H and CAS0L - that would be bank 0 .

RAS1 goes to modules where go CAS1H and CAS1L - that would be bank 1 .

So much for now.

Edited July 12, 2019 by ParanoidLittleMan
There was mistype

[+chicgamer]

3 hours ago, ParanoidLittleMan said:

So, if you want I can write you detailed connection plan - to say so.

Yeah, if you can give me an idea of exactly what connections to make, that would be great!

 

If it would help, I can take additional pictures of my board.

[Lynxpro]

On 7/12/2019 at 9:38 AM, chicgamer said:

Thanks for the info! I bought the SIMMs yesterday. Now to figure out what all wiring needs to be done ...

 

I may contact B&C in case they happen to have any documentation for installing the board. I'm a little concerned that no one will respond (it looks like pages have been down in B&C's store for a while).

 

B&C operates primarily on eBay under the account "MyAtari". You could try contacting him through there...

 

[+chicgamer]

Cool, thanks for the info!