mnelson@cbnewsl.att.com (michael.c.nelson) (03/11/91)
I've been having some trouble with random files in comal.
Anyone out there still use it? I have an old c64 (an early
one with the buggy video, tan case) and an old 1541 (white
case!). Comal version is 0.14.
Anyway, I open a random file (or relitive in CBM's view) write
some stuff and read it back. Sometimes it's OK but then the
first block will develop a problem of everyother variable
(floating points: 5 bytes) is 0.
The following is a typical scenario:
- Use 'Comal Handbook' example to create and write random
file. (I added a few extra fp variables)
- Use 'Comal Handbook' example to read random files.
- Everything's OK.
- execute:
open file 3,"0:e.dat",read
close
// This opens the file as seq then closes it.
- Rerun the write and read programs and the data comes
back trashed.
The problem occurs with writing the data. I've edited the
disk to add the missing data and read always seems to work.
One really strange thing is that if I create a new random file
the problem will repeat, ie. the data is OK the first couple
of times then gets corrupted. BUT, if I delete the file, even
change the name, but it ends back up at the same disk block as
the old file, the problem appears immediately.
Any idea what's going on? I understand there were bugs in the
old 4040 drives with relative files. I understand that the
1541 is based off this drive. Could some of the 4040 problems
made it into the 1541?
Mike Nelson
AT&T Bell Laboratories
Naperville IL
USA