Re: New idea HD for C=
Date: 1999-09-06 23:00:36

Hallo Richard,

> 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.

NO, with some exceptions IDE-drives are 16 bit. Anyway I did not want to use 
this port to remain compatible with SW which do need this port like SPEEDDOS 
and Star Commander. My Idea was to add the interface I develloped and presented 
to you at the beginning of this year.

> Unfortunately software is not my strongest point, so:
> 1. Have the 1541 ROMs been disassembled and fully documented yet?

AFAIK no :( Please somebody, tell me I'm wrong !!! (and prove it too)

> 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.

256 sectors and 255 tracks = about 16 MB.

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

IMHO you only have to find out where data is written to/read from the 6522-port 
responcible for the data to/from the floppy and the stepping-motor. At this 
point you cut in to re-route the data to the HD. But the biggest problem will 
be the file system on the HD itself. This is one of the reasons I preferred 
working on the system using a PC

> 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.

But who garantees that the C64 (or PC) is tristated when you want to access the 
HD ??? IMHO that is out of your control.

Groetjes, Ruud

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