View Full Version : IMSAI Fix Pt 4: Best way to copy a boot floppy with limited tools?

April 30th, 2015, 09:02 PM
Hi all,
For those who have been following my IMSAI fix thread, you may be aware that I basically now have the system up and running. Cool!


Before I progress any further, it is imperative that I make a few backup copies of the bootable CP/M disks (2) I have.
The disks themselves are a little flakey, and I can not always boot from them, and I get a lot of BDOS errors. However I can get to the '>' prompt occasionally, so this is a very good sign, and gives me confidence that good copies can be made.

I have done DIRectory listings on all the floppies I have in the hopes that some would contain the programs I need to do the copy process.
There is a program called COPY.COM, and I have to fully explore this, but on first trial, I got a lot of clanking with the heads raising and lowering quickly on both drive A and B, which didn't seem normal. I quickly stopped this, thinking that heads slamming up and down can't be good for my marginally bootable disks.

The only other programs I have available on disk are PIP.COM (as of yet untested). No FORMATting or SYSGEN programs at all.
I may try COPY.COM again, but I'll have to be careful.

As an alternative, I was wondering if anyone knows what my options are for making a bootable backup?

My best guess is that I need to install a Monitor program in EPROM which will probably live just above the FF00h CP/M boot EPROM. I'd also install EPROMs containing FORMAT.COM and SYSGEN.COM. The idea is that I would boot into CP/M (so itís in RAM), then reset and launch the Monitor program, then using it to move the FORMAT program to 100h, and execute it. If that works and I can FORMAT a blank disk, then I would repeat the process moving the SYSGEN program to 100h, and execute it. Hopefully this will generate a nice clean formatted boot floppy. Will this work, or is my approach somehow flawed?

Any advice would be greatly appreciated.