Re: Format sequence

From: Craig Taylor (
Date: 2006-05-28 02:55:01

There are probably a number of areas that you can "clean up" or skip over to
find more space in the drive RO M of the 1541.

Ones that immediately spring to mind:

&0: functionality - not sure it would be helpful / usable with your

disk 1 handling - remains of them are there but are not really relevant.
Unfortunately it's all spread out so to gain any usable space you'd have a
fun time shifting things around...

The duplicate disk (C932 - C951) routine.

Possible the concatenate format of the copy command as it's rarely used:
C96E - C9A0.

** Note above addresses are not guaranteed - just from a quick glance
through the ROM's.

- Craig Taylor

On 5/27/06, <> wrote:
> Hallo allemaal,
> I have my 1541LPT project working :) It hasn't been fully fool proof
> tested
> but it works. I can format a 'disk', save and load a one-liner and read
> the
> directory. And IMHO the rest should work as well as in fact I only altered
> the parts that are involved with writing to or reading from the floppy-
> disk.
> Some technical information:
> - one only needs to add a 6522 to the board and solder a 25 pin
> D-connector
> to the 6522.
> - I mentioned adding extra 2 KB of SRAM but you can forget that. At this
> very moment I'm only using TWO bytes of that RAM and IMHO it shouldn't be
> difficult to find a home for them in the first 2 KB.
> - At this moment the extra ROM part is 778 bytes big. The original format
> routine alone needs about 640 bytes and so, together with the unused 256
> bytes at $C000, I could squeeze it in the original ROM. But that would
> mean
> no extra commands at this moment like "changing disk".
> - The PC runs a little Pascal program. At this moment it loads an
> hardcoded
> D64 image. It is not much trouble to alter so it will use a parameter to
> tell it what disk to use. There is a way to tell the 1541 that the PC has
> 'stopped' and started again. In this case the 1541 will reset as well.
> Future:
> - I first will optimize what I have at this moment.
> - Add some extra commands like 'change disk'
> - Maybe using G64
> - Find out if I can find a place for all the routines inside the original
> - Making a JiffyDOS version. FYI, the only part that my program affects is
> the format routine.
> --
>     ___
>    / __|__
>   / /  |_/     Groetjes, Ruud
>   \ \__|_\
>    \___|
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