1541LPT

From: Baltissen, GJPAA (Ruud) (ruud.baltissen_at_abp.nl)
Date: 2006-05-29 09:22:45

Hallo allemaal,
 
 
> I have my 1541LPT project working :)

I tested it with the programs 'check disk' and 'performance test', found on
the original 1541 test disk and all worked fine.

Some additional technical information:
- The PC runs a little Pascal program. At start-up it loads an hardcoded D64
image. But I altered the Initialize command in a way that it accepts an
extra parameter. This parameter tells the PC what D64 image to 'load'.
- The speed: 
 - The original Kernal has to wait for the wanted sector to pass the head.
In case of 1541LPT the wanted sector is presented the moment it is asked
for. 
 - I shortcircuited the stepping routine and it is definitively is faster
then the original. But the routine checking if the motor is running or not
is still in place so things could be improved here yet.
 - Formatting a track is now sending two bytes to the PC and that's it. 

Future:
- Maybe using G64 image. At this moment I use the ID found in the BAM as ID
found in the sector header as well. Programs using different ID's in
different sectorheaders as copyprotection will detect an error and stop.
Using G64 can avoid this.
- Making a version for JiffyDOS, SpeedDOS and other speedloaders. FYI, the
only part of JiffyDOS that my program affects is the format routine.
- Using 'bigger disks'.  This could be done by shifting all needed
'calculations' to the PC; in this way the 1541 only acts as a pass-through
station. This could have an impact on the compatibility of course, but
imagine the gain.
- Now I'm using an extra 6522 as interface. Imagine using an USB interface
instead....

My future plans:
- First thing to do: creating a page on my site with all info, schematics
etc.
- Making a 16 KB version
- Making at least a JiffyDOS version
- Bigger disks
- Knowing how to do the trick with a 1541, I could do the same trick with a
1571 and 1581. With the 1571 no additional hardware is needed as we can use
the onboard 6526! 


--
    ___
   / __|__
  / /  |_/     Groetjes, Ruud
  \ \__|_\
   \___|       http://Ruud.C64.org




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