"intelligent" disk drives

[Tony Duell]

> 
> On Sat, Nov 17, 2007 at 12:40:25AM +0000, Tony Duell wrote:
> > I've never seen a 2031, but all the GPIB-interfaces double drives contain 
> > 2 processors I think.
> 
> The 2031 is very much like a 1541, but with an IEEE-488 interface rather
> than C= IEC.

Interesting. As I said, I've never seen one, in fact the only CBM GPIB 
drives I've been inside are the 8050 and 8250LP.

> Prior to the 8050/8250, I think the arrangement was one 6502 to talk to
> the bus, and one 6504 to talk to the drives, but in other respects, the
> same.

I wonder why they changed? I've not got the data book in front of me, 
what was the address space of the 6504? The 8050 needs 8K, I think (4K 
shared RAM + ROM + I/O devices). Did the earlier drives have less shared 
RAM or something?


>  
> > The control processor ROM is in one of those 6530 RRIOT chips, which 
> > makes replaicng it a little problematic...
> 
> I have, I think, a full set of 2040 ROMs, including the right 6530, but
> most of my pre-8050 drives were originally 2040s that were later upgraded
> to the same ROMs as a 4040 (the only difference AFAIK is the label on the
> outside).

I seem to remember the 2040, 3040 and 4040 were all similar. One of the 
upgrades was just a ROM swap, but I thought the other upgrade involved 
rather more. But as I said I never used said units.

As an aside, IMHO one of the worst mistakes commodore made was that the 
8050 could not at least read the disks of the earlier drives. 

-tony