Re: Transfer a 8250 diskette

From: Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de>
Date: Thu, 10 Nov 2011 17:51:11 +0100
Message-ID: <4EBC00FF.1010505@laosinh.s.bawue.de>
On 11/10/2011 08:33 AM, Nicolas Welte wrote:

>> 1541B ROM RELEASE NOTES: 251968-02   (16K byte, 300ns, checksum=$1A69)

That's the second revision ROM used in the 1541C, the one with the track 
zero sensor.

>> 3.  SAVE-@ (SAVE with replace) is fixed.  The variable  NODRV is now a
>> 16-bit addressable var,  and the STLBUF routine steals the buffer locked by
>> drive one.

If the fix is in 251968-02, then all 1541-II should be safe since they 
use 251968-03.

Makes me wonder about the 1551 and 157x. Did they get the fix too? 
Especially the 1551, there is only one ROM revision I know of.



>> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>>   PLEASE NOTE:  THIS ROM WILL _NOT_ WORK IN EARLIER 1541 PCB'S, WHICH
>> REQUIRE DIFFERENT SIZED ROMS (8K),  AMONG OTHER BOARD DIFFERENCES!
>>   * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

If the difference is only the physical ROM format, then it should be 
possible to use 251968-03 in an old 1541 with some extra work.

The other differences he's refering to might be the track zero sensor. 
Using 251968-03 should be no problem then, the 1541-II doesn't have one.

  Gerrit


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