(Non-) Issue with 8MB CP/M

Discuss construction, troubleshooting, and operation of the Altair 8800c computer

(Non-) Issue with 8MB CP/M

Postby BillO » February 26th, 2022, 11:55 am

Hey folks. It's been a while ..

So, I boot up to 8MB CP/M through a serial connection and everything is more or less fine. I can load up any program and run it. The system seems very stable. I was running Zork for a whole week, going back to it to play it when I got a few moments. However, I copied the blank 8MB disk image to create a new disk image, mounted it, formatted it (with the 8MB format) then I tried to copy MBASIC to it and gave an error. Smaller files, like PIP.COM, copy and run fine from the new 8MB disk, but not MBASIC. Has anyone else had this problem?

I really want to create a 8MB disk I can use for writing programs in BASIC, C and assembler (and anything else I can find).
Last edited by BillO on March 18th, 2022, 1:51 pm, edited 2 times in total.
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Re: Issue with 8MB CP/M

Postby AltairClone » February 26th, 2022, 7:22 pm

Interesting... I can’t imagine why MBASIC would be different than any other file. I’ll see if I can find time this weekend to duplicate the problem. What are you mounting as the source disk for MBASIC? Does MBASIC run when started on that source disk?

Mike
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Re: Issue with 8MB CP/M

Postby BillO » February 27th, 2022, 12:59 pm

Hi Mike,

The MBASIC is coming off an image with the name cpm22b23-56k.dsk and it does indeed run fine when started from that disk. Maybe it has to do with file size?
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Re: Issue with 8MB CP/M

Postby AltairClone » February 27th, 2022, 6:53 pm

Hmm, it's working fine for me. Note that 8MB CP/M expects 8MB disks in drives A and B. Regular disks like cpm22b23-56k.dsk should mount in drive C or D.

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Re: Issue with 8MB CP/M

Postby BillO » February 28th, 2022, 7:09 am

That's the way I have it. 8MB disks in A and B.

I wonder if I might be getting some noise over the serial connection. BTW I'm using it at 230.4K. The higher speeds were not as reliable with the older computer I was using as the server. Have not changed it yet.

Do you have a preferred USB to serial chipset?
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Re: Issue with 8MB CP/M

Postby AltairClone » February 28th, 2022, 12:29 pm

The USB adapter I'm using uses the Prolific 2303 chip set. What is the exact error you're getting from PIP or CP/M?

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Re: Issue with 8MB CP/M

Postby BillO » March 1st, 2022, 9:14 am

Sorry for the late reply mike. Temporarily out of town. Will test again a provide results when I'm back on the PIP copying of the MBASIC.COM file. As for running it from the copied location, the machine just locks up after some disk accesses. I'll time that too.

Thanks for your support!
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Re: Issue with 8MB CP/M

Postby BillO » March 3rd, 2022, 7:14 pm

Okay,

I'll record this as I do each step.

Shut down WIdnows PC and restarted. Started up serial server. Set com port and speed. Loaded in 8M CP/M, 8M Blank, regular CP/M and zork into Disk 0, Disk1, Disk 2, Disk 3 respectively.

Power up and reset Altair 8800c. Examine F800. Run .. booting into monitor. G FF00 .. booting 8MB CP/M wihtout issue.

Use FORMAT8M to format B: drive (that takes a while .. time to pour a glass of wine and catch up on your emails) .. completed without issue.

Copy PIP.COM from A: to B: - PIP B:PIP.COM=PIP.COM .. completes without error. DIR B: verrifies file copied

Copy MBASIC from C: to B: - PIP B:MBASIC.COM=C:MBASIC.COM .. completes without error. DIR B: verrifies file copied

Switch to B: drive - B:

Invoke MBASIC - MBASIC .. seems to load for about 4 seconds then drops to ALTMON.

Halt and reset Altair 8800c. Examine F800. Run .. booting into monitor. G FF00 .. booting 8MB CP/M wihtout issue.

Switch to C: drive. Invoke MBASIC. Loads up no issue.
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Re: Issue with 8MB CP/M

Postby BillO » March 3rd, 2022, 7:20 pm

Oh, BTW I was wrong in my first post. The PIP I copied to B: does not run correctly either.
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Re: Issue with 8MB CP/M

Postby AltairClone » March 4th, 2022, 9:47 am

That's great detail and will help me duplicate your issue. I should have some this weekend to dig into it.

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