CP/M survey

[Allison]

>
>Subject: Re: CP/M survey
>   From: Jeffrey Armstrong <jba at sdf.lonestar.org>
>   Date: Thu, 19 Apr 2007 12:08:11 +0000 (UTC)
>     To: cctalk at classiccmp.org
>
>
>>> >
>>> >Subject: CP/M survey
>>> >   From: Mark Tapley <mtapley at swri.edu>
>>> >   Date: Wed, 18 Apr 2007 09:09:45 -0500
>>> >     To: cctalk at classiccmp.org
>>> >
>>> >DEC Rainbow (8087, 832k (max for -A model), but
>>> that's irrelevant to CP/M-80).
>>>
>>> Not true as the rainbow also ran CP/M-80/88 as it
>>> was a dual CPU (has a z80).
>>>
>>> Allison
>>
>> Could it access more then 64k under CP/M-80? Don't
>> you mean CP/M-86? Not to nit pick...
>> I don't know about specific Rainbow revisions, but I
>>was under the impression the 'bow could go up to 896k.
>>Maybe I'm thinking of the Tandy 2000 via an 3rd party upgrade.
>
>I think Mark was trying to say that an 8-bit CP/M program on the Rainbow 
>can only access 64k RAM, which is true, under Rainbow CP/M-86/80.  A 
>16-bit program could access all of the Rainbow's system RAM under CP/M.

Of course and I referred to that.  What I avoid trying to do was say, hey 
it's a Z80 and 8bitters like 8080 and Z80 without only address 64k.  Granted
you can hang bank hardware on them and extend but the addressing is
still only 64k.

>And he's also right about the memory.  A 100A maxed out at 832k, while a 
>100B/100+ maxed out at 896k.  This is because 100A models shipped with 
>128k on the motherboard, while 100B/100+ models shipped with 192k.  So 
>when a maxed-out ram expansion card was installed, the 100A still had 64k 
>less than an equivalent 100B/100+.
>
>One interesting thing about 16-bit programs on CP/M-86/80 on the Rainbow 
>was that some were confused by too much RAM.  The most notable examples 
>are all the Rainbow ports of Infocom adventures; they all complain about 
>"not enough memory" if you have more than 512k or something like that.

Unlike PCs were 640k was all there was.


Allison