🚀 go-pugleaf

In article <664@lzaz.ATT.COM> hcj@lzaz.ATT.COM (HC Johnson) writes:
>In article <1280@hiatus.dec.com>, chad@norge.dec.com writes:
>> 
>> Hi
>> 
>> I would like to know if replacing one row of 256kb chips (16 chips)
>> with one row of 1 megabit chips in a 1040 or 520STFM/upgraded will
>> give the magic 2.5 meg RAM on the motherboard.  Is there a problem
>> with this?
>> 
>> Also, I would like to DIY upgradethe old style 520 to 1 meg using
>> any method not requiring an add on board.  That means most likely
>> piggybacking.  Could someone please post what needs to be done to
>> do this. Ie, any extra parts needed, any pins not to solder, any jumpers, etc...
> 
>1. 1 meg drams are narrow, 256k drams are wider.  there may also be a differ-
>ence in pinouts.  my ezram-II uses 3 (thats three) plug in strips for
>each ram position--wide for 256, narrow for 1 meg.
>
>2. my second atari is a 520ST with a 1 meg upgrade.  each chip has piggybacked
>on it a second 25k dram.  All pina are soldered except for the chip select.
>It works, and there are no connectors to work loose like my ezram.
>
>Howard C. Johnson
>ATT Bell Labs
>att!lzaz!hcj
>hcj@lzaz.att.com

What?  1 Meg rams are 18 pin devices - 256K rams are 16 pin devices
They are both packaged on 0.300 inch wide spacings.
/leonard
.]