View Full Version : Sysgen command in CP/M 2.2. Can it be used on disk which already have data/programs?

March 20th, 2010, 07:02 PM
Now that my Kaypro is up and running again (http://www.classic-computers.org.nz/blog/2010-01-26-keyboard-problem-on-kaypro.htm)I'm picking off from where I left off. At the time of failure I was creating disks using Dave Dunfield's utilities and also giving the Kaypro a "burn-in" test. The beast is running a low-mem check as I speak. Last time I did this the machine had the keyboard issue after it was through. Fingers-crossed not this time.

Many of the images I've got off Dave's excellent collection are non-bootable. The question is this? Can I execute a SYSGEN command from the CP/M system disk directed at these disks to make them bootable or will that damage files? I suspect the latter, but my web search for information seems ambiguous on this point. Some sites suggest this procedure doesn't damage existing files. SYSGEN'ing an existing disk created from a image will be much quicker than creating a blank formatted bootable disk then PIP'ing all the files to it.

A related question. Some of Dave's images are copies of the original bundled disks which came with the Kaypro II. Booting the disks gives you a message that these are originals, copies should be made and these ones should be stored in a safe place. Fair enough, but even if you make copy using the COPY command as instructed in the Kaypro II manual (http://www.classic-computers.org.nz/blog/2010-01-26-kaypro-II-users-manual.htm), the message still appears??? Can anyone throw any light on this? Instead of using COPY, does a blank disk need to be formatted, SYSGEN'ed and then all the files pip'ed over?

Any comments most welcome.


March 20th, 2010, 07:21 PM
Most but not all CP/M 2.2 implementations put the boot, CCP, BDOS and BIOS on reserved tracks that are not part of the file system. The idea is that at either cold or warm boot, the necessary data can be streamed into memory by reading contiguous sectors (i.e., you don't need the BDOS to read the BDOS).

So, you're very likely safe to simply transfer the system onto a new floppy with existing files.

N.B. There are some systems that format the boot tracks with a different layout to improve boot speed or to make them universally bootable (e.g. FM on a disk that's otherwise MFM allows a loader to tell you that your system doesn't support MFM).

But that Kaypro IIRC, is not one of these.

March 20th, 2010, 09:21 PM
This ^^^^

Cannot speak for the Kaypro, but...

On the 4p w/ Montezuma, there are multiple formats and some of them are 'data disks' that have the directory moved down to track 1.
If I attempt to 'sysgen' one of these the directory would be totalled!

Might be good to check (STAT) the disk in question to see if RESERVED TRACKS exist and provide enuf room.

(Am booting from HD now so nearly all FDs are 'data disks' but do still have a couple of bootables...)

March 21st, 2010, 02:22 AM
I have implemented SYSGEN on my non-bootable disks without any apparent ill-effects.

Thanks for the comments.