[CSDb] - User Forums - Release id #40365 : 25 x Turbo

Welcome to our latest new user Rodrigo Yeowtch ! (Registered 2024-11-24)

You are not logged in - nap

CSDb User Forums

Forums > CSDb Entries > Release id #40365 : 25 x Turbo

2006-09-21 07:29

tlr

Registered: Sep 2003
Posts: 1787

Release id #40365 : 25 x Turbo

Does anyone know the origin of this code...

Info:
Turbo at $e000-$e88d. ($e406 called by the small init at $014b)
Trackbuffer $e900-$fdff.
Transfer decode buffer $fe00-$ffff.

Quick analysis:
Init:
* There is no init except setting up the load vector.
* The load vector points to $014b.
* The routine at $014b copies some kernal routines ($ed00-$f0ff) to
ram under kernal and then jumps to $e406.
* At $e406 the filename is checked for '$' and device numbers below 8,
at which it skips out to $f4a6 for normal load.
* $e42c, print searching...
* $e433 loader init starts.

Loader:
* $e457 copy bootstrap to drive
At $e817 the drive code is stored, pre-M-W-encoded. Each command is
terminated with a $ff marker, and the last command is terminated by
an additional $ff marker.
This code is just a small bootstrap ($0706-$075f) waiting for the
rest of the code.
* $e489 copy the real drive code by high speed transfer.
Copies the code $e000-$e405 (inclusive) to $0300-$0705, resulting in
code from $0300-$075f.
The drive then jumps to $04af.
* $e4b2 speed load the entire track 18 for fast file finding.
* $e4d1 find the file with wild cards.
* $e529 file found, t/s to $b4/$b5
* $e542 print loading
* $e549 check for invalid track. Luxury! smile
* $e55c send track number
* $e566 load entire track.
* $e56d sector out of range for track?
* $e573 load sector data from track buffer until the track changes,
after each loop call $e59c to flush the buffer to memory.
* $e593 file loaded, flush buffer by calling $e59c a last time.
* $e599 exit out, done.

Load entire track at $e725:
* $e725, initialize sector count, set number of sectors to $a3. Start
on sector 0.
* $e742, call $e61f to get one block in two halves from drive to
$fe00/$ff00 and merge it into $e900+sector number using the two 32
byte tables at $e7ab and $e7cb. Checksum to $d7.
* $e748 add interleave 3.

... 30 posts hidden. Click here to view all posts....

2024-10-03 11:16

tlr

Registered: Sep 2003
Posts: 1787

Still no sign of the origins of this. I'm still wondering.

2024-10-03 17:06

chatGPZ

Registered: Dec 2001
Posts: 11352

Did you check 64er disks?

2024-10-05 16:09

tlr

Registered: Sep 2003
Posts: 1787

Quote: Did you check 64er disks?

I think I tried a bit a long time ago but couldn't find a comprehensive collection of them all.

EDIT:
Searched a bit again and eventually found somewhere that Amica Paint was originally published in 64'er Sonderheft 27 (1988).
The disk can be found here: https://www.planetemu.net/rom/commodore-c64-magazines-d64/64-er..

This disk contains the loader MOST-ACCESS C000, which surprise, is very similar to the other MOST-ACCESSes I've seen. It is however completely different to the BKS imported one discussed here so I find Graham's claim dubious. He does claim it's a text edit of MOST-ACCESS II though, so I guess that loader may be available somewhere else?

Previous - 1 | 2 | 3 | 4 - Next

Refresh

Subscribe to this thread: