Re: More info A curious small circuit baord from a "]["?

[greg@apple2.com]

In article <389A3231.84D39184@ripco.com>,
Jonathan Schattke <wizwom@ripco.com> wrote:
>CUTblakeney@home.com (Jeff Blakeney) wrote:
>>Jonathan Schattke <wizwom@ripco.com> wrote:
>>>greg@apple2.com wrote:
>>>>Jonathan Schattke <wizwom@ripco.com> wrote:
>>>>>god23%heaven.org@teleport.com (Bart) wrote:

>>>>>> I am curious: if one pulled the 64k RAM on the motherboard, and 
>>>>>> replaced with 256k can it be addressed or is that a waste of 
>>>>>> time?

>>>>> Nope, it's a waste of time.  The hardware would not be able to 
>>>>> access any more RAM.

>>>> Would it be a suitable replacement for when the correct RAM chips 
>>>> go bad and the proper chips can no longer be obtained?  If it can 
>>>> only access a portion of the RAM, can it still access that portion 
>>>> reliably?  Provided suitable pinouts or adapters?

>>> Yes, the 64K DRAM used 8 Rows and 8 columns, the 256K used 9 of 
>>> each.  The extra address line should be grounded, then it will work 
>>> fine.

>> Well, depending on how you want to access the RAM above 64k, it is
>> possible to put 256K chips in place of the 64K ones and get more
>> memory.  [methods described]

> It would be nice if that would work, but you'd have to make up a 
> circuit to go through each of the 4 banks for refreshing, otherwise 
> you would lose the memory to charge leak.  Now, you're not talking a 
> very complex circuit, but it's a lot more difficult than I expect that 
> greg was looking for.

Actually, I was just pointing out a reason why someone would install 
larger memory than spec and wondering if that reason was indeed valid.  
I don't own an ][ or ][+.  Basically just countering the "it's a waste 
of time" statement.

Well, partly theory.  I have a IIgs memory card where I can't seem to 
find the ZIP DRAM chips I need to fully populate it.  Also, I don't 
discount the possibility that my //e or //c might not need a memory 
transplant in the future.  (The //e also has a RamWorks II that could 
use populating.)

That and I need card stock which would allow me to use a ribbon slot 
mover (if I can find where I put it) so my RamKeeper would fit in the 
case better with the non-AE card in the back slot.

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