Re: MFM drive gone nuts

From: Julian Perry <>
Date: Thu, 24 Jul 2014 00:21:52 +1000
Message-ID: <>
Hello smf,

Thursday, July 24, 2014, 12:05:02 AM, you wrote:

>>When I said early PC's, I meant early PC's with fixed  IDE definitions in 
>>the BIOS. XT class machines didn't store drive definitions in BIOS, that 
>>was the job of the controller.

> I assumed by early pc's you meant around 1981-1986.

> Fixed IDE types in the BIOS were a problem and there were issues moving IDE
> drives between computers with different BIOS.
> You also can have problems with swapping drives between RAID controllers, I
> saw problems moving SCSI drives between controllers in unix.

> I think there were similar stories with Amiga controllers, it wasn't just a
> PC thing.

>        Message was sent through the cbm-hackers mailing list

There's better.

I got stung BADLY with an EISA DPT ESDI controller once (PM2012B). Those had an
external ROM that managed disk dimensions, but interrogated the EISA
BIOS first to guess a "best fit" for the boot dimensions. Once
booted, the drivers took over, and allowed the rest of the drive to be
used (larger than the original int13 parameters would allow.). I went
and flash-updated the motherboard ROM to fix a UNIX panic issue - on a
customer's production NEC machine. Very kindly, NEC ALSO updated their
drive table..
The DPT controller found a "Closer fit" - switched drive dimensions
underneath the OS, and it no boot no more. :sadface:
No way to downgrade, either - had to replace the motherboard.. (a 2+
hour task)

Customer was not amused. Neither was I.

They were awesome controllers for the time, though.


       Message was sent through the cbm-hackers mailing list
Received on 2014-07-23 15:01:31

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