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CP/M on an HP-86/87XM
Message #1 Posted by Mike on 7 Aug 2003, 5:30 p.m.

I have a nice HP-87XM system that I was going to sell. I wanted to include the CP/M Module as well but I don't seem to be able to get the CP/M to boot.

The system has 384K of RAM, the CP/M module and I have an original CP/M disk. But, when it tries to boot, I get an error saying, "operating system not on drive A, please correct and hit any key" or something to that effect.

Drive A?

Should I have a 2nd disk? Is this a sign that my CP/M disk is bad? I have a 2nd CP/M module and it behaves the same.

Does the CP/M module have to be in a specific slot?

Is there any setup required besides just booting from the floppy?

Re: CP/M on an HP-86/87XM
Message #2 Posted by Vassilis Prevalakis on 9 Aug 2003, 2:52 a.m.,
in response to message #1 by Mike

Sorry for the delay, I had to find the CP/M module first :-)

You only need one floppy, here is the directory:

[ Volume ]: HPCP/M
Name        Type   Bytes     Recs
CP/MSYS     DATA     256     1021
Autost      PROG     256        5
CP/M        BPGM     256       25

Autost is a Basic program:

50 END

File CP/MSYS is the CP/M filesystem (your DRIVE A). If you try to use the native COPY utility, you are likely to corrupt this file. You have to use the CP/M PIP command.

The floppy behaves like typical Autost floppies: if the floppy is in the drive, the system loads Autost, runs it and boots into CP/M, if the floppy is inserted after the 87 boots into Basic, you can still LOAD and RUN the Autost program and boot into CP/M. If you press [SHIFT] RESET you get back into Basic.

Once CP/M is up, you can do a DIR and see the files that exist inside the CP/MSYS (filesystem) image.

BTW, if you happen to have the software for the HP 82900A terminal emulation co-processor, then this should be usable with the CP/M module, since the actual hardware card is the same for both systems. Unfortunately, I do not have this S/W.


Thanks for info but...
Message #3 Posted by Mike on 9 Aug 2003, 11:58 a.m.,
in response to message #2 by Vassilis Prevalakis

Sadly, I have an original disk and it still does not boot. That doesn't mean that it wasn't overwritten at some point.

My program file list matches what you have here. The autost program is slightly different but that is a file that is configured to match ones system so it makes sense that it might be different. For instance the printer is at a different location.

I suspect that my master disk may be corrupted.



Just a guess..
Message #4 Posted by Vieira, Luiz C. (Brazil) on 9 Aug 2003, 3:02 p.m.,
in response to message #3 by Mike

Hi, Mike;

I'm not aware of using CP/M, but I found some troubles on floppy system disks in other systems that were solved by starting with another disk drive unit. I'm not sure if you can do one of these:

- prepare another CP/M startup disk (or system disk)
- use another disk drive unit
- clean the head(s) of the existing drive unit

As I mentioned, I never used any CP/M-based system, I just thought about this and maybe it's nonsense. Anyway, maybe current drive (the one you are usiing) is able to read disk information and disk contents, but somehow it cannot read startup (system) data. I once found a multi I/O (daughter)board that was able to do enything EXCEPT prepare a hard disk as a system disk. I tried whatever you can imagine: use another I/O board, prepare another hard disk, use the same hard disk prepared in another computer, use the "bad" daughter board in other computers... That multi I/O board was not able to write startup information. It was able to read but write. And the problem was only when using that board.

There are things one must go too deep inside the system's inner secrets to explain...

Qapla' (as Ernie thought me as being Klingon's world for Success!) Please, let us know if/when you succeed.

Luiz (Brazil)

Edited: 9 Aug 2003, 3:08 p.m.

Copying CP/M floppies
Message #5 Posted by Vassilis Prevelakis on 9 Aug 2003, 3:10 p.m.,
in response to message #3 by Mike

OK, then I'll send you a boot floppy.

For the rest, here is a list of what I had to do to create the new diskette:

Conventions: I assume you have two floppy drives and you are booting from the lower numbered one. This will be drive A (like in MS/DOS). The second drive will be drive B.

To copy the boot floppy you have to boot with it and when you are within the CP/M environment you have to perform the following steps

1) Format diskette and install the CP/M system files

Run the FORMAT command, select option 2 (Create CP/M system diskette), and follow the instructions.

2) Copy user files from the master diskette

Assuming the master disk is on drive A, and the new disk on drive B, use PIP B:=A:*.*

Warning: Unlike most systems, the PIP syntax is Destination := Source

3) Use DIR A: and DIR B: to confirm that the files have been copied.

Notes: The FORMAT command is not a standard CP/M command, it was developed by HP for the Series 80 CP/M emulator. I do not have the HP CP/M documentation, but you can download the CP/M 2.2 OEM docs from


Holy CP/M Batman... (Photos)
Message #6 Posted by Mike on 9 Aug 2003, 7:46 p.m.,
in response to message #5 by Vassilis Prevelakis

It worked!

I guess I hadn't tested the original masters as I thought I did. I tried again and it booted. Guess I won't need that floppy.

The images below show the boot screen.

Photo 1: This is what the CP/M boot screen looks like

Photo 2: This is a screen that shows results after creating a new Master CP/M disk.

Photo 3: This shows the same disk when viewed using CAT from the BASIC environment.

Now, how to get a bootable 3.5" disk

Thanks VP

Edited: 9 Aug 2003, 8:25 p.m.

Re: Holy CP/M Batman... (Photos)
Message #7 Posted by Vassilis Prevelakis on 9 Aug 2003, 11:18 p.m.,
in response to message #6 by Mike

I have used a 9121 3.5" disk all along, so there is nothing fundamentally wrong with CP/M and 9121 disks.

The setup I have here does not have 5.25" disks. I have a 9121 (HP-IB device 0), a 9122 (HP-IB #4, used with the EMS ROM) and a ThinkJet printer (HP-IB #5).

CP/M has the following drive allocation:

   DRIVE           CP/M
9121 left drive      A
9121 right drive     B
9122 left drive      E
9122 right drive     F

So there is a gap in the drive numbering (C and D are missing).

My guess is that maybe CP/M does recognize all your floppies but you don't know what drive letters to use.

Try booting CP/M with both types of floppy connected and then try using drive letters till the floppy access led lights.

I have done this scan by placing a normal HP-85 floppy on the 9122 right drive (not a CP/M floppy) and executing DIR B:, DIR C:, DIR D:, DIR E:, etc till the drive mechanism engaged.


That did the trick
Message #8 Posted by Mike on 10 Aug 2003, 12:22 a.m.,
in response to message #7 by Vassilis Prevelakis

I had to swap my drive letters to make my 5.25 the boot drive. Then, it was a simple matter to format a 3.5" disk on drive E: and copy the system files to the 3.5" disk.

Now, I have CP/M bootable from 5.25" or 3.5" depending on the drive letter setup.

You have been a great help. There is a lot of good documentation here.


PS: I owe you one, or two, or three

Edited: 10 Aug 2003, 12:24 a.m.

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