Intel DD format differences

From: Steve Thatcher <melamy_at_earthlink.net>
Date: Tue Feb 22 05:34:14 2005

make that 3740 format...

as for the marks, yes they are different and I don't recall that being a problem with the TI controller I was looking at (I have one of them, but my data sheet to go with it has been lost...).

the headers (other than the ID address mark being different in value) contain the same number of bytes in the same order. Intel's format had 0 in the byte location (third byte) that said which side it was supposed to be (in other words side 0) and they had 0 in the location that defined the sector length (fifth byte - 1 for 128 byte sectors).

Unless Intel did the CRC different, these should be the only differences.

Eric, the gap and PLO sync bytes are in the DD system 34 format. They are not in the 3740 format that I was talking about.

best regards, Steve Thatcher


-----Original Message-----
From: "Dwight K. Elvey" <dwight.elvey_at_amd.com>
Sent: Feb 21, 2005 9:10 PM
To: cctalk_at_classiccmp.org
Subject: Re: Osborne-1 SD format

>From: "Eric Smith" <eric_at_brouhaha.com>
>
>Steve Thatcher wrote:
>> all Intel did was to use the same basic 3270 format and double the number
>> of sectors to make the OS changes easy. The gaps between real data did not
>> get as big from SD to Intel's DD.
>
>Intel made more changes than that. In addition to the use of M2FM and
>and different gap sizes, the index mark, ID address mark, data mark, and
>deleted data mark don't match standard FM or MFM. The gap and PLO sync
>bytes are different as well.

Hi Eric
 I'm almost sure that the headers of the sectors have something
different in them as well. I recall looking at it and thinking
that it was just something else that needed special handling.
Dwight
Received on Tue Feb 22 2005 - 05:34:14 GMT