Re: New idea HD for C=

From: Richard Atkinson (
Date: 1999-09-05 05:36:55

On Fri, 3 Sep 1999 wrote:

> Connecting an IDE-drive to a 1541
>       The idea is to addapt the above interface so it can be used by the 6502
>       in an 1541-drive. Then you have to change the Kernal. Problems: 1)
>       there is no listing INCLUDING comments etc. available. 2) Even if you
>       have the listing, it is very tough material to understand. 3) what
>       about PRGs who directly address the 6522 used for the transferring the
>       data from/to the floppy

I *really* like this idea. As we all know, the 1541 has a spare 8 bit port
on one of the VIAs, and that's exactly what an IDE interface would need in
addition to a decoded bit of address space and a little bit of glue logic.

Unfortunately software is not my strongest point, so:

1. Have the 1541 ROMs been disassembled and fully documented yet?

2. Is CBM-DOS capable of accessing large drives? If not, it would have to
be implemented as a large number of virtual disks, which might not be a
bad idea as it would get round the no-subdirectories limitation.

3. For the 1541 code experts: approximately how much hardware-specific
code would have to be changed?

Having one or two IDE devices with their high data bytes on the VIA port
does not preclude using it for parallel transfers to the C64 as well, as
the IDE bus goes high impedance when not being accessed.


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