Olivetti M21 swap board with AT&T 6300?

[snuci]

I am not familiar with these computers but I recently got an Olivetti M21 because it's a very cool looking portable. It boots up to a certain point (stops at the NPU test) and then never goes further. This M21 does have an MFM hard drive (ST-225) and does some initial seeking, then that red light stays on until turned off. It has the Rev 1.36 ROMs and the AT&T 6300 has 1.43 ROMs (it also has a hard drive) but I don't have a monitor to see if it works.

As a test, can I add the keyboard connector to the 6300 motherboard and put it into the M21 straight up? I just want to see if the 6300 motherboard works and if it does, I can swap the ROMs and the PALs to see if that makes a difference.

Any help is much appreciated.

 

[NeXT]

Visually it looks like the two are identical in layout. I'm not seeing anything out of place to say there was a board variation.

 

[1ST1]

M21 and M24/6300 use the same mainboard, maybe on the desktop version only the pin header for the M21 keyboard is missing.

As if it stops at NPU test this might be because of missing i8087 (numeric processing unit). So fixing that might be easy, there is a switch on the mainboard which tells that there is an 8087 or not.

See cap1.pdf out of the Pocket Service Guide.

 

[snuci]

Thanks for the feedback and thanks for the document @1ST1 . I did swap out the motherboard once I put in the keyboard header on, swapped the firmware and PALs between boards which works fine. The AT&T 6300 had a hard drive and half-length hard disk controller that was different so I tried that and even swapped out the hard drive and after all that, it was the same. Turns out, it was my keyboard! I guess there's no "Keyboard Error" message? That was literally the last thing I tried as I was going to reply and cry for help here

I don't think I described the boot up well enough. It hung AFTER the NPU check and did nothing more. No floppy/hard drive access attempts or anything. Glad I figured that out but I wanted to post my solution in case someone else sees this post. The little board on my keyboard was not tight so securing that better made the floppy work. Note: I did NOT have flashing lights on the keyboard either. The light was solid on NUM LOCK only during the whole boot process.

Thanks again.