Re: CP/M + (3.0) disk images posted to the web

[pausch@saaf.se (Paul Schlyter)]

In article <ap9536$cis$1@rage.aladdin.de>,
Christian Groessler  <cpg@aladdin.de> wrote:
 
> mjmahon@aol.com (Michael J. Mahon) writes:
> 
>> Christian Groessler wrote:
>> 
>>> Formatting with 2.2 does work, thanks.
>>> What card I have? I don't know :-) I got it from ebay and it has 4 dip
>>> switches and no hint who the manufacturer is.
>>> But it works so I don't care :-)
>> 
>> The 4-position DIP switch is a giveaway--it's a Microsoft SoftCard
>> clone.  That's handy, since most Apple CP/M software was intended
>> to be run with the SoftCard.
> 
> What are the dip swiches used for?
 
They're used to control various pieces of hardware behaviour for the
SoftCard.  With one of them, you can for instance turn off the
hardware translation of Z80 addresses to 6502 addresses; with another
one you can make the Z80 execute at full speed (4 MHz) instead of
running two cycles then idling two cycles (allowing the 6502 CPU to
refresh its internal registers).  But if you do any of this, Softcard
CP/M won't work... :-)
 
For use with Apple Softcard CP/M, all four switches should be in the
OFF position.  The only reason to want to put them in some other
position would be if you didn't run SoftCard CP/M but some of your
own custom Z80 code (if you want to do this, the Z80 Cross Assembler
version of the S-C Assembler could be useful -- it's available for
download at my Apple II page at tiscali.se -- see my .sig for the
full URL).  However I know of no software which needs these switches
to be set in any other position than all four being OFF.
 
If there's interest, I can dig up information about what these
switches actually control.
 
-- 
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Paul Schlyter,  Swedish Amateur Astronomer's Society (SAAF)
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