Junkbox CP/M system?

Allison ajp166 at bellatlantic.net
Tue Apr 24 13:50:15 CDT 2007


>
>Subject: Re: Junkbox CP/M system?
>   From: Holger Veit <holger.veit at iais.fraunhofer.de>
>   Date: Tue, 24 Apr 2007 15:35:10 +0200
>     To: General Discussion: On-Topic Posts Only <cctech at classiccmp.org>
>
>Allison schrieb:
>>> On CF, IOCS16- is honored--but it's not on any IDE  hard drive you're 
>>> going to buy today.
>>>     
>>
>> I've heard that was true of any drive over 500mb and have not seen anything
>> over 80mb that does. 
>>
>> Me I keep saying if you really need the simplicity of 8b transfers and 
>> the low cost that comes from a surplus IDE drive just ignore the high 8bits
>> and enjoy it.  There's no harm from that.  So what if half the storage
>> is unused, likely the drive is large anyway.
>>   
>You are going to lose the error flags from the status register which a 
>transferred on D8-15, IIRC.
>Also the drive identify command will return only half of the data.
>It is not an issue with pure data blocks; you'll then just have 256 byte 
>blocks rather than 512.

Both are minor issues.  CP/M cannot use the identify and a bios that uses it
to configure is going to grow far to fast.  The error bits are a minor problem,
sufficient to say if you get an error (low 8bits signal generic error) whats
one to do? Answer, not much as something big happened.  CP/M doesn't handle 
errors the bios does.  It's simplistic but 99.999% of the time unless there's
a programming error where the host and drive are out if sync, errors mean
it's time for a new drive.


Allison

>
>-- 
>Holger
>




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