• Please review our updated Terms and Rules here

Found the problem - corrupted disk image

retrohimpi

Member
Joined
Jun 11, 2010
Messages
36
Location
Saffron Walden, UK
Damn! It was a corrupted boot disk image all along. After tracing BASIC execution through interpretation of the first statement without finding anything obviously amiss I tried booting from a different disk image and, bingo, I got a menu of games from its BEXEC* program. I could play Hangman and beat the computer 2 times out 3, so I don't think there's a lot wrong with my emulator.

attachment.php


Out of the 6 C1P-MF disk images I downloaded, only 2 will boot, so I suppose I'd have had to be pretty lucky to have picked a good one first time. If the corrupted bytes are in the binary executables I don't think there's much chance of finding or fixing them, as without a checksum there's nothing to distinguish them from good ones nor any way to know what they were originally.

I think the next step is to make a copy of one of the good disks and then try making my disk emulation write as well as read. I don't think this will require much extra code, as all the track/sector seeking code is in place and working, so all I should need to do is to respond to the write line when it goes high and copy the resulting stream of bytes on the serial line to the right place in the disk image. First, though, I must bone up on the OSI disk BASIC commands as I've no idea how to save a BASIC program to disk.
 
lotonah;bt364 said:
Any progress on this? I don't know much about the OSI, but I have the entire run of Compute! magazines now and there's some stuff I'm itchin' to try :)

Sorry, I've only just got back to this now that the long dark evenings have returned. I'm concentrating on finding the remaining bugs in my 6502 emulation. Other C1P emulators are available - see http://osi.marks-lab.com/index.php, for example.
 
Back
Top