Re: CBM900 hard disk timeout

From: MikeS <>
Date: Sun, 24 Aug 2014 16:38:12 -0400
Message-ID: <169579C659624B36B050A4E8E6DDB060@310e2>
I'd try to exhaust all other possibilities before formatting the disk in 
case there are any rare files on it.

Did you have a pull-up resistor on the index line when testing?

I want to test this drive before I send the board to make sure it works but 
I have to find and set up a compatible system first; I'm also waiting a bit 
to see if you get yours working without it.

In the meantime it might be useful to have aorking drive for comparison.


----- Original Message ----- 
From: "Michał Pleban" <>
To: <>
Sent: Sunday, August 24, 2014 3:39 PM
Subject: Re: CBM900 hard disk timeout

> Hello!
> Michał Pleban wrote:
>> 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").
> I have checked it some more and it turns out these are simply SASI
> commands. So the floppy controller uses the command 04 which means
> "format disk", which makes perfect sense. The hard disk controller does
> not support this command, but it does support command 06 which means
> "format track". It might be theoretically possible to hack some Z8000
> code to send this command to the controller to see what happens.
> Regards,
> Michau.
>       Message was sent through the cbm-hackers mailing list 

       Message was sent through the cbm-hackers mailing list
Received on 2014-08-24 21:00:33

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