RE: Who owns a 8050/8250 with tandon drives?

From: Martin Hoffmann-Vetter <>
Date: Sat, 17 May 2014 18:37:46 +0200
Message-ID: <001d01cf71ee$56102ed0$>
Hello William,

>> Btw, is DOS 2.1 released after DOS 2.5?
> It's been a long time, but I think DOS 2.1 came first.

There is an reference to "Commodore Drives are History Part II" from Jim
Brain (Commodore World, Issue 18) where jim listed the 8050 between the 3040
with DOS 2.0 and the 4040 with DOS 2.1. So it's possible DOS 2.5 was
designed before DOS 2.1 was released.

> I think the 5 in DOS 2.5 refers to the 500K disk format.

This is an nice idea. ;-)

> What about 2.6?

This is the DOS for the single cpu version 2031/1541/1551. This is a 170 kb
disk format (see DOS 2.1), based on DOS 2.5.

> The double sided format is DOS 2.7.

This was designed later. It support super side blocks for large relative

> Was there
> something in between, or did they leave an extra number in case it
> would be needed?

They need and used this version number. It's in the right chonology
sequence. The problems starts with DOS 3.0. There are two main versions
known. First is based on DOS 2.7 for the 8280 and 9060/9090. The second DOS
3.0 was many years later released and based on the DOS 2.6 for 1571. The
question is, was some code fragments from the DOS 2.7 or early DOS 3.0 used
in the later DOS 3.0? At this time i try to analyse this. But it seems there
is nothing from them in the later DOS 3.0. Only the DOS 10.0 (1581) use some
things from DOS 2.7 and/or DOS 3.0 (specially super side blocks support).

The other question is, what's about the 8061/8062? It was sold after DOS 2.5
was current and before DOS 2.7 is designed. But the capacity was so great,
it must be use super side blocks.


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Received on 2014-05-17 17:00:03

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