[comp.sys.atari.st] 4M & 2.5M

440488@UOTTAWA.BITNET (Doctor Who) (10/07/88)

In article    paul@cacilj.CTS.COM (Paul Close)write:
In article <...> lharris@gpu.utcs.UUCP (Leonard Harris) writes:
>>Datafree in Toronto is selling a 2.5 / 4 meg expansion board that plugs in

>Question: why are all the boards for 2.5 or 4 meg?  As I understand it, the
>ST can have 2 banks of memory.  I have a 1040, so that's one bank with one
>meg.  If I add 1 meg on the other bank, that's 2 meg (just like the mega-2).
>Where, then, do the 2.5 meg boards come in?
>--
>Paul Close    paul@cacilj.CTS.COM     ...!{uunet, ucsd, crash}!cacilj!paul

A Mega 2 does not have another 1 meg bank. It uses 16 1Mbit chips which
is 2 megabytes of ram.
Each bank has 16 places for ram chips. Chips can be 64K, 256K or 1M bit
A 1040 has 32 256K chips...adding this board in allows you to use either
256K or 1M bit chips in only one of the banks while the other take only
1M bit chip.....so a bank with 256K chip and another bank with 1 M chips
gives 2.5M

Doc'
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