Mounting Hard Disks in CP/M 2.2 - Limitation?

[Steve Lamb]

Hi, Group members.  I am new to the Altair Emulation world.  I was mounting hard disks the other day and apparently hit a limitation.  Here's the scenario (copied from a previous Facebook post a few days ago):

I am testing hard disk mounting and access. The switch positions I use are the following:

A12/A13 up to select the hard disk controller

A8/9 down to select platter 0

A8 up/A9 down to select platter 1

A8 down/A9 up to select platter 2

A8/9 up to select platter 3

A0-A5 to select the disk to mount

I select the hard disk controller, and mount disk 'w' on platter 0

I select the hard disk controller, and mount disk 'x' on platter 1

I select the hard disk controller, and mount disk 'y' on platter 2

I then boot disk 'w' (A1/2/3 up, Aux 1 down). All is good. I see the A> prompt and can do a DIR on B> and C>. So I then mount disk 'z' on platter 3. No mounting issues at that time.

At this point, I try to access D> or do a DIR D: and the system locks up.

I try the same scenario again, with only a boot disk mounted on platter 0. DIR A: shows directory of platter 0. But if I do a DIR D:, than in several tests, rather than getting the expected BDOS error, the system locks up or I see a disk directory listed that is not related to the actual mounted disk - in one particular test, I had a hard disk mounted, but Dir D: display the dir for Floppy Disk 7 (SuperCalc).. Sometimes, I get a BDOS error. It's random.

Anyone else seeing this, or can replicate it?

Is there a limit for the number of hard disks that can be mounted in CP/M 2.2? If so, does there exist or would it be possible to create a bootable CP/M 3.0 hard disk image? I know that is possible for a floppy disk, as it is supplied with the Arduino image collection, but I'm not finding a HDISKxx.DSK bootable image for CP/M 3.0??

Thank you for shedding any light you can provide on this newbie question.

[Steve Lamb]

Sorry.  Was the same question from a different group member sometime back and am reviewing that response.  Thank you.

[John Galt]

cp/m 2.2 was hacked to allow 2 Harddrives at a time there is a 5mb drive image that is more of a true Harddrive, then there is a 8mb redefined floppy drive image.

you can not mix them and you can only have 2. where it will be 2 hard drive images, either 5 or 8mb, and 2x 360kb disk images, you can not use the 1.2mb floppy images.

i personally recommend the 5mb over the 8mb as there are issues with the 8mb images there is also a version of the 5mb with 1024 allowed file entries over the original 255 entries.

 

cp/m 3 as far as i have looked never supported hard drives and very few people are really interested in playing with cp/m 3.0.

there is a very slight increase in the TPA of cp/m 3 over 2.2 however basically 99% of the cp/m software was made to run under 2.2 and it has been extended so much over the years that cp/m 3 isn't worth really playing with.

this is my opinion having messed around with things for a few years.

My setup is x2 5mb hard drives running CP/M 2.2 V1.6 for MITS 88-HDSK, with a patched IOBYTE for the LST device and 1024 directory entries MP/M extensions and tools, 2x standard 360kb disk drives.

https://github.com/ratboy666/hd1024

[Andy]

nice setup, BTW 

Andy