Re: Reading Commodore 900 disks in the 8250 (LP)

From: Didier Derny <didier_at_aida.org>
Date: Thu, 11 Jan 2024 20:09:19 +0100
Message-ID: <bfa8f452-badb-4895-84da-8e1144f371c0_at_aida.org>
Hi


Don't remember how but there is a way to load and execute code for the 
second 6502 used has fdc

it was used by a software named "Silicon Office" to protect their floppy 
disk...

the company I was working for Procep (selling commodore in france) asked 
me to write a program to copy their disks...


I forgot the details but I just remember that I had do upload code for 
the second 6502...

you probably need the source code of the DOS and analyse the dialog 
between both processors

they have a shared memory  (the program has to be placed in this memory)


--

didier


Le 11/01/2024 à 12:55, Michal Pleban a écrit :
> Hi!
>
> Baltissen, GJPAA (Ruud) wrote on 10.01.2024 14:44:
>
>> Regarding formatting a disk, the software, that is executed by the 
>> 2nd 6502 (FDC controller), can be found in the ROM of the first 6502, 
>> the bus controller. The 1541 uses the same principal so you could 
>> start with studying that one first. Main advantage: everything in one 
>> ROM.
>
> Well, I guess then my specific question is: how do I execute code on 
> the second CPU? When I send a "Memory-execute" or "user" command to 
> the drive, it is being executed on the first CPU, correct? With the 
> 1541, when everything is run on the same CPU, you can surely execute 
> drive-interfacing code this way, but how to do it when there are two 
> CPUs involved and only the DOS-CPU is user-facing?
>
> Regards,
> Michau.
>
>
Received on 2024-01-11 21:00:04

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