Re: Speed of AE Z80plus ?

[mjmahon@aol.com (Michael J. Mahon)]

Moll wrote:

>Greg Buchner wrote:
>> In article <20040801025044.10926.00002773@mb-m02.aol.com>,
>>  mjmahon@aol.com (Michael J. Mahon) wrote:
>> 
>>>(Unoptimized
>>>screen I/O that switched to the 6502 on each character compounded
>>>the sluggishness.)
>> 
>> I always thought that was just something inherent in Z-80 computers.  I 
>> worked at a place for a while that used Dec Rainbow 100's 
>> <http://www.cedmagic.com/history/dec-rainbow.html> and the screen when 
>> running under the Z-80 mode was incredibly slow.  It was like using the 
>> VT-100 part of it at about ~4800bps.  The company had these computers 
>> and all they used was the Z-80 side of them, even though they had some 
>> MS-DOS software sitting around that was loads faster.  That would do 
>> near instantaneous screen updates.
>> 
>> Greg B.
>
>You know, that makes me wonder if a nearly all-native CP/M 2.2 BIOS 
>could be written, that only uses the 6502 for drive access.

It certainly could, for the cards that have direct access to Apple video
memory.

Of course, that might be a bit at cross purposes, since the really fast
CP/M cards for the Apple II did not have direct memory access, instead
passing all data a byte at a time through I/O ports.

-michael

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