Alpha Micro 1200

mamorim01

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Oct 11, 2020
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A bit of an oddball. I had been meaning to dig into this computer for a while, but lack of space and concern about its condition ended up pushing it to the back of the queue, but I finally managed to find some time to do some minor cleanup. The Alpha Micro 1200 is a multi user system, powered by a Motorola 68010 processor and fitted with 1MB of RAM (upgradeable to 4MB). It also sports a SASI hard drive, QIC streamer tape and it can be booted from a VHS video tape (!). The operating system is AMOS/L, a derivative of DOS-11 used in the PDP-11 computers (Alpha Micro was eventually sued by Digital, if memory serves).



Detail of AMOS help options.



And detail of the frontplate.



I would be keen to image the hard drive as getting bootable media nowadays would be a pain but it looks like it is going to be a bit of a challenge. From what I could find out online, the boot PROM is matched to a specific Xebec controller that is embedded on a customized ST-506 drive, so the boot PROM would need to be modified if the original drive died in order to use some other SASI compliant device.

I powered it up today and it boots without a fuss. I am hoping I can manage to preserve it somehow.
 
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mamorim01

Member
Oct 11, 2020
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www.thegarage.space
I appreciate the tip, I can't say I had previously heard of this board. It is pretty slick, actually. You can apparently ssh into the BeagleBone and issue commands to read the disk from there, so it acts as its own host and is capable of handling the drive by itself. It simplifies the drive image dumping process a lot, and it certainly addresses one of my concerns.

I will open the case this week and will dig into the drive to try to make sense of what I see. What I have read about the Alpha Micro / Xebec controller and boot process is merely but a footnote, so I would like to understand it a bit better. Odds are the emulator board may not be able to fully support this arrangement, but if anything might be able to do the trick, I think this would be it.

Even if this might not do, I can see how this board would be helpful in some other use cases, so I will definitely be ordering one sooner rather than later.
 
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mamorim01

Member
Oct 11, 2020
33
22
8
Spain
www.thegarage.space
I would talk to David Gesswein djg@pdp8online.com and consider getting one of his drive emulator boards...
Finally managed to find some time and investigate inside the case and, as it turns out, it is fitted with an 8bit SCSI drive, a Micropolis model 1375, instead. It looks like both options (SCSI or ST-506) could be selected during purchase and only the ST-506 drives were fitted with custom, embedded, Xebec controllers. I *think* it should be possible to simply dump the drive using normal means, so I will try with a Sparcstation and a SCSI2SD which I have at hand.

In any event, I definitely keep an eye on that MFM emulator board as I have some old IBM gear which could use imaging and/or replacement with more modern means.

All the stuff going on in the left sector of the board is handling the eight serial ports. I *think* the square custom chip on that sector could be part of the SCSI controller.



Opening up the case



And details of the hard drive.

 
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