Disk Images

[D “DT” T]

Hi All,

First timer here - Just finished building my Altair-Duino pro 3.0 and love it!

In regards to the disk images - I have learnt how to navigate around and load them - all good!

MY question is - Can I load multiple images so that I can have for example a CP/M A:, B: and C: at the same time and able to switch between them please?

Apologies if this has already been answered - I did some searching but couldnt find anything.

KR,

Darren

[udo....@freenet.de]

darren.t...@gmail.com schrieb am Dienstag, 11. März 2025 um 14:49:43 UTC+1:

MY question is - Can I load multiple images so that I can have for example a CP/M A:, B: and C: at the same time and able to switch between them please?

No, this system is build to always boot from drive A: and then it runs what is on the system tracks there. You can put

other CP/M disks in B: ... of course and access files on them, but you cannot boot from B: ... 

[Patrick Jackson]

This is described in detail in the older print manuals for the Altairduino but here's my best telling:

The first 4 LEFTMOST address switches need to be set to determine disk type

The next 4 address switches denote platter/drive (to me its semantics, to others its very important XD )

The RIGHTMOST address switches will be which Disk to mount

So, if I want to mount CP/M with Aztec C hard drive disk image (I have this on my sd card) I will do:

DDUUDDDD DDDDDUDU
to mount disk 5 on platter/disk 0

Then if I want to also mount my own hard drive disk with my tools (its hard drive 7) I will then mount like this:
DDUUDDDU DDDDDUUU
to mount hard disk 7 to disk/platter 1. This will now be drive B:. If I then boot to the hard drive loader, I will boot on drive A: (disk/platter 0, mounted disk 5) and disk B: will be disk/platter 1, mounted disk 7

I hope this helps!

[Tom Wilson]

Yes, you can have multiple images on your SD card, and you can quickly choose which one you want to boot to in the main menu or with the switches. 

Personally,  I think it's a lot simpler to use the menu than to have to remember a bunch of switch combinations:

Hold up START and push the left AUX up, and you get the main menu. In there, I have the disk boot ROM as my Aux1 Up selection, and I have my favorite CP/M disk selected as my boot disk. 

Save that to the default profile with "S".

After that, you can easily switch disks in the menu, then once you have exited the menu, just press Aux 1 Up to boot to that disk. 

[D “DT” T]

Thanks All for your responses. I understand now. 

Much appreciated !!

Darren

[David Williams]

You can certainly have multiple floppy disks, or a hard disk and floppy disks mounted at the same time. You just have to make sure all the drives you have mounted can be read by the OS you're booting. My default profile has the adventure games hard disk and 4 CP/M floppy disks I can either boot the A: floppy and have the 4 floppys as a, b, c, and d, or I can boot the hard drive as a, and have two of the floppys as b and c. Another profile boots Altair disk basic and has a second drive with more BASIC programs.

[markepi...@gmail.com]

Hey yall,

Since we are talking about mounting and disks, I need to ask.  I;m new at this too.  I cant seem to create a new disk image per instructions.  I mount a non-existant disk image and I can't format it.  If I do a a>b: i get a bad sector error.  not unexpected.  Format shows all kinds of sector, tracks and size data but I get the same kind of errors when I try to switch to b:.  I followed the instructions from Atomic Shrimp on youtube (load CPM on drive 1 and Zork on drive 2) and I can bounce back and forth from a: to b::. How do I create a new disk image so that I can store data and programs on a blank disk?

Thanks

Mark

[Richard Deane]

You could copy a good one and delete the files to create an empty disk.

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[markepi...@gmail.com]

I would like to know that too.  Not really clear in the instructions on page 13.  I'm sure I did this on my older version of the Altair-duino but that was a while ago.  pip doesn't work nor does sysgen.  Trying to understand before I hook up my new floppy disk !!!1

Argh.

On Wednesday, December 24, 2025 at 11:57:23 AM UTC-5 John Galt wrote:

Is there actually a way to create a new disk image file on the SD card without removing it and coping a new image file to it?

[Mark Episcopo]

Still working it but when I looked at the sd card on my pc, I did see that the altairDuino did create an image.  I just can't get to it !!!!!

On Wednesday, December 24, 2025 at 8:46:11 PM UTC-5 John Galt wrote:

in looking it at this evening you can copy an existing file to a new name, you can't add that to the lookup data file so the comment information will be missing, but otherwise its just a copy of existing and not a new fresh disk file.

thus a copy will require you to erase all the files inside CP/M or your O/S of choice.

[da...@hansels.net]

In general it should be possible to create a new disk image by assigning a currently not used image number to a disk drive. This is only possible via the front panel switches.

I tried it here and I'm seeing similar problems. The disk image gets created but it is not properly formatted after formatting completes and therefore is not usable. 

I am looking into what is causing that.

As a workaround, formatting the same disk image a second time seems to result in a proper usable image. Can you try that and report back? If that works then it is likely I am seeing the same issue as you are,

David

[da...@hansels.net]

I found the problem that was causing this and have fixed it in my Altair8800 GitHub repository.

If anyone comes across the same problem in the future, either update the firmware to the latest version

or use the workaround of formatting the image twice.

David