RE: Upgrade 2040/3040 DOS 1 floppy drive to DOS 2?

From: Hoffmann-Vetter, Martin <>
Date: Fri, 30 Jul 2010 23:45:50 +0200
Message-ID: <003501cb3030$9666bcf0$1b09a8c0@mhvnb10>

> However, I have just realized they're not broken - they are just
> stuck with Commodore DOS 1.X as opposed to the 2.X versions I am
> used to.

Some commands are'nt implemended in DOS 1.

> if there is any way to upgrade them to a newer DOS version.

Yes, you can update from DOS 1 to DOS 2 by changing the DOS-ROMs (901468-06
and 901468-07 for DOS 1 to 901468-11, 901468-12 and 901468-13 for DOS 2 or
901468-14, 901468-15 and 901468-16 for DOS 2 Rev.) and the RIOT (901466-02
for DOS 1 to 901466-04 for both DOS 2 versions).

> My EPROM programmer can handle 2532 chips,
> so upgrading the ROM is not a problem, but I have noticed that a
> DOS 2.x floppy drive uses a different 6530 RIOT than a DOS 1.

Correct, you must change the RIOT, too.

> If I only upgrade ROM and keep the original RIOT, will it work at
> all?


> Is there any custom DOS 2 compatible version that could be
> made to run with a board otherwise equipped for DOS 1?


> Is there some known replacement circuit for 6530 chips? I see there
> exists BIN code from a DOS 2 chip, so I assume there is a way to
> program an "emulation" as well. I do realize it contains RAM, I/O
> and timers so not trivial.

Yes, have a look at the 8250LP, SFD1001 or the disc in 8296-D. Alle these
bords have a doutherboard for the RIOT (e.g. 251252 rev. A for SFD1001 -
. Because Commodore don't put the new DC code for some DOS 2.5 and 2.7
versions in a new RIOT. They hide the ROM from the RIOT and put the new DC
code in an additional EPROM (2716). So you can use a RIOT from any commodore
floppy with any code.

Best regards

Martin Hoffmann-Vetter

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Received on 2010-07-30 22:00:04

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