Re: CBM900 hard disk timeout

From: Michał Pleban <>
Date: Sat, 23 Aug 2014 15:52:36 +0200
Message-ID: <>

Clockmeister wrote:

> What you need is a dump of the controller ROM and check with a hex
> editor to see if  formatting software is present on the ROM.

I have pasted the controller firmware disassembly here:

The disassembly claims that the controller supports commands: 01, 05,
06, 08, 0A, 0B, 0C, 0D, 15, 16. I am struggling too much with the 8048
assembly to verify it, but let's suppose it's true.

The BIOS disassembly shows the following commands are used:

02 - Restore Drive (?)
04 - Format
08 - Read
0B - Seek
0C - Init Drive (?)

The floppy controller ROM disassembly shows that it supports, among
others, commands 04, 08 and 0A which would make sense taking into
account the above BIOS uses (0A is supposed to mean "write").

So, it appears the controller firmware does not support the command 04


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Received on 2014-08-23 14:00:03

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