View Full Version : New to me IMSAI PCS-80/30

July 3rd, 2014, 04:47 PM
Today I took delivery of a few items that I am very excited to get back up to working condition. The star of the lot is an IMSAI PCS-80/30 but it's ability to operate is currently unknown. I'm going to inspect it over the next few days as I have time and eventually plug it in and see what happens. It currently has a couple of wires disconnected from the main transformer that look like they slipped off in transit. I have full manuals to figure out how to fix it, I think. The previous owner said it used to work but at last attempt, it did not. Various cards including the VIO card were not seated properly when it arrived. One can hope but that would be too easy a solution, I think.

Here's a pic:


The IMSAI IKB-1 Intelligent Keyboard is an early version that doesn't have any graphics on it yet. In fact, the documentation for it is marked "Preliminary". I don't have the parallel cable but I would imagine it's a straight-thru cable 25 pin - 25 pin cable? I'll have to dig into those manuals. I have both the PCS-80/30 Reference and Operating manuals as well as documentation for the S-100 cards. In a second binder is some hand written assembly code, a PTDOS manual and three or four Dr Dobb's Journals from 1977. In the binder is also a copy of MicroChess for 8080 and an IMSAI product line brochure. It truly is a time capsule.

Cant wait to try to get this operational.

July 4th, 2014, 11:12 AM

Where is the gold mine that you keep discovering all these great computer systems? You are one of the luckiest people I have seen around here.

I only saw one of these personally once way back when. I would love to get my hands on one of these! And you have all the documentation, too! I am thinking of coming up there to Canada and renting a house near you so I can stalk where you go to find all this great stuff. ;-)

Good luck to you. I am looking forward to hearing all about your progress with this one.



July 4th, 2014, 12:42 PM
Thanks smp. Your going to hate me but there's more to this story...

This lot also came with a Sol-20 that the owner thought was the keyboard for this. It's an honest mistake from someone who acquired it but never used it except to turn it on and then store it as was the case for this owner. In fact, I also thought the Sol-20 was being used as a terminal because the seller didn't mention any other keyboard nor did I see pics of it. So technically, it WAS the keyboard in a matter of speaking. Let's just say I was pleasantly surprised when the IKB-1 keyboard was looking at me when I opened the package. With no labels on it or graphics, I had to open it to check. It's an IKB-1 Rev 0. Is it normal practice to put Rev 0 on a board? The Sol-20 also doesn't have the normal faceplate on it. It has the following as shown in the pic.


The Sol-20 has no S100 cards and also lacks a personality module so I'm thinking it must have been used as a terminal. Does the absence of a personality module allow it to run as a terminal? I do have a manual in the binders for an Electrohome V14 surveillance monitor, so that must have been used with the Sol-20. The PTDOS manual has me a little confused. Unfortunately, there was no Sol-20 documentation. While there is no Helios-II that would match the PTDOS manual, there were also two Micropolis 1035-II dual drives that came in the lot. Here's a pic. The one of the left looks rough but the faceplate still has the protective plastic on it.


I have not been able to find any reference including pictures, manuals or mention of these drives and they are not 1033/1053s. I'll open those up and see what's inside. I do have a Shugart Associates SA400 Minifloppy Diskette Storage Drive manual in the binders but I think that's for the North Star enclosure. If anyone has experience with these Micropolis drives, I'd be grateful for any information. Note, they are beige exterior and not blue so maybe it's a normal drive with a different paint scheme so it has it's own model number?


I think I may have a good portion of two separate systems here and maybe the Micropolis drives go with the Sol-20? I don't have a Micropolis controller in the PCS-80/30 but it is wired for the North Star drive, including extending power to the drive from the PCS-80/30 power supply.

The Sol-20 has a couple of breadboard mods in it and also has power extended from the Sol-20 power supply to something that was external.

It's like CSI, trying to piece this together and figure out how and why they fit. I'm not 100% sure they do it but it will be fun trying to figure that out. If anyone can help, I'd love to hear it. Do those Micropolis work with anything here? That's all I got.

July 4th, 2014, 01:02 PM
Yes, I remember your previous posts. I also seem to remember some posts about KIM-1, as well. Wasn't that you, too? ;-)

I love that someone has been able to acquire this equipment and attempt to get it back going, instead of simply staying in a closet until it gets cleaned out and thrown away by some unknowledgeable person.

I cannot really help you with most of your questions. I never got a chance to see a SOL-20 in person, and, as I said, I saw an IMSAI PCS-80/30 only once.

I do recall that Processor Technology made their SOL-20 systems available to other companies for re-badging. That is probably one of those that you have. Heaven knows what was removed from or put into your system, or whether you even have it all now. I know that you have received assistance and replies from deramp5113 (Mike Douglas) about the SOL-20. I think he may be one of the savviest folks here who can assist you with evaluating what you have, and how to put it all back together again.

Good luck to you. I look forward to your posts about what progress you are making. This is exciting stuff!


July 4th, 2014, 03:09 PM
My guess is the sol-20 was sold as a dedicated word processor. "The basic computer group" was the word wizard company out of Canada.

I would also suppose it might have predates the word wizard program and could have been hooked directly up to a diablo printer. With no card backplane you can just plug a ram card in if they needed more than 2k and a personality module could have contained the word processing software. Cassette IO could have been used for storage easily.

I have no evidence for this, just an educated guess based upon who the label is from and that it doesn't have the word wizard keyboard stickers attached to the keyboard section of the case. Leading me to think it predates the release of word wizard.


July 4th, 2014, 04:04 PM
So I spent a little time on it so far. After plugging in all wires correctly, reseating all of the cards and double checking connections, I figured it was time. Lucky I saw Ken Vaughn's videos and studied his website (Thanks Ken!) so I attempted to fire it up without the keyboard or floppy drive attached...


Hit the reset button and Success! I literally said "Hello" back because I wasn't expecting that :) I shut it down, connected the floppy drive and started it up. Nothing blew up so that was good. Now for the keyboard. I found a 25 pin straight through cable and carefully checked all of the pins. I don't want to recreate Ken's unfortunate event when his nephew, I think it was, used the wrong cable. I checked every pin against every pin just in case. Looks good.

Being extra cautious, I read about the internal jumpers on the IKB-1. I had to take that apart again but now completely. I did notice that when I thought it said Rev 0 it actually said Rev 1. I don't know how I mixed that up but it was now clearly visible.


Next was the jumper check. All looked well according to the Reference manual. This keyboard can be used through a parallel or serial connection. I confirmed it was parallel.


I looked to see how the MPU-B board was supposed to be configured because that's where the parallel port is on a PCS-80/30 but I figured that since the keyboard was set up right, the MPU-B board must be correct also. So I plugged it in and turned it on and hit the Reset button. What followed for a few minutes was chaos. The screen was flickering, characters were being entered and lines were being executed. I tried the "Mode" button which puts the keyboard in an internal programming state and things stopped. I hit it again and chaos ensued. So I did what any uninformed user would do and started kitting keys at random with varying weight; hoping to see that character show up on screen. The actual goal was to loosen possible stuck keys that had probably not been pressed in decades; literally. Then calm ensued and I could type characters; the ones I actually pressed.

Once things seemed normal (and realizing I didn't know what to do next), I shut it down and started it back up to see if chaos would return. It did not so I shut it down once again, put the only floppy I have that came in the North Star drive back into the drive and went to YouTube to see what Ken Vaughn did. He also had a North Star drive so I figured I'd try what he did.

Sadly, this is where the story ends for now. I entered KE800 which jumps to the North Star boot sequence, saw the drive light come on but didn't hear any spinning. I'll now have to slow back down again and crack open the drive enclosure and check that thoroughly. I also quickly realize I don't know what I'm doing so I need to do some research and read some of the documentation that came with the computer.

I did manage to get into a monitor program but I don't remember how. I think I hit Control-C when I tried to stop the insanity with the keyboard but I'll have to check what I did and read up on it. I managed to catch a picture of the IMSAI SMP/80.0 monitor but have no idea what to do so I ended that session there.


That's where I am now. Typing this in an celebrating with a beer. Hope you found this of some interest.

July 8th, 2014, 04:40 AM
My guess is the sol-20 was sold as a dedicated word processor. "The Basic Computer Group" was the word wizard company out of Canada.

I think that is very plausible. I made a similar connection because the equipment came out of British Columbia which was where "Basic Computer Group" was from. I assumed that it might be a system for word processing but I didn't know you could have a "Word Wizard" personality module. Makes sense. The Sol-20 (that I haven't explored yet) has a power extension from the power supply to a four pin external cable. I am guessing this is to power a floppy drive of some sort but it doesn't match the Micropolis drives that came with the lot.

Sadly, this lot didn't come with any disks that would have greatly helped figure out how this system was used but one of the binders had hand-written machine language of the various routines in the IMSAI VIO SMP/80.0 monitor and documented addresses for various internal routines. Through wild speculation, maybe this system was originally from one of the "Basic Computer Group" programmers. Perhaps they were in the process of porting "Word Wizard" to the PCS-80/30 or similar systems with the IMSAI VIO card? That would be an explanation that would tie these two systems together. Maybe far fetched but plausible :)

July 8th, 2014, 03:03 PM
I was troubleshooting the North Star drive. Since it's an SA400 drive, I tried to jump to $E900 and still the light would come on but no drive motor. I checked voltages and found that it was getting 18v and 9v from the IMSAI power supply but the regulator board that converts it to 12V and 5v was only outputting 5v. No 12v output so I just ordered an MC7812CK voltage regulator. We'll see when that comes if I can get anywhere.

I am banking on my one dusty warped floppy to work. If anyone has a documented procedure on creating a North Star DOS boot disk on a hard sectored disk with no original DOS disk, I would be grateful for a link. I have a 10 hole punch jig to make hard sectored disks.

Thanks in advance.

July 8th, 2014, 03:33 PM
I think that is very plausible. I made a similar connection because the equipment came out of British Columbia which was where "Basic Computer Group" was from. I assumed that it might be a system for word processing but I didn't know you could have a "Word Wizard" personality module.

Actually the Northstar drive maybe makes more sense... PT had a lot of trouble releasing the Helios II. So maybe they had a SOL-20 northstar setup they OEM'd with word wizard or some earlier word-process that inspired them to make word wizard.


July 8th, 2014, 04:08 PM
Actually the Northstar drive maybe makes more sense... PT had a lot of trouble releasing the Helios II. So maybe they had a SOL-20 northstar setup they OEM'd with word wizard or some earlier word-process that inspired them to make word wizard.

That would certainly make sense but the North Star drive is hardwired to the IMSAI power supply and it has the North Star controller in it.

The SOL 20 has external power wires also but they don't match the North Star drive nor do that match the Micropolis drives. It also has other mods. Here's a few pics of the mods. Maybe you can help decipher them if you've ever seen anything like this or if anyone else has seen this for that matter.


I haven't hey turned it on because I want to inspect it better and the power supply mod in picture 4 scares me a little but I will eventually try it.

Let me know if you've seen something like this or what your thoughts are if you haven't seen it.

July 9th, 2014, 11:47 AM
Hey, nice find! I don't hang out here much anymore - life has been incredibly busy the last 12 months or so. But a friend of mine suggested I should come check out this thread.

It is interesting to see your progress on getting the PCS 80/30 going again. I've been in the process of restoring a broken PCS 80/30 for a while now, knocking down one problem at a time, and uncovering another. Recently, I had it working perfectly for a short time, until something else seems to have gone haywire.

My documentation is marked "PRELIMINARY" as well - and I don't think that's terribly odd- I think only about 1500 of these machines were produced, so I'm sure quite a few say "preliminary" on the hardware reference manual front page, as mine does.

Also, I believe you may be jumping into the wrong address for the disk controller - it will depend heavily on your specific setup, but E800 is the correct location on my setup, which also has hard sectored drives, but no longer uses the NorthStar controller (instead it has a MicroComplex dual-density controller).

Needless to say, out of necessity, I'm becoming more and more familiar with the internal operations of this machine- if you have any troubles that come up, feel free to shoot me a PM - that is the best method to ensure I notice, because it will shoot me an email to let me know you've sent one.

July 9th, 2014, 04:13 PM
Hi TX_Dj,

Thanks for dropping in. It's great to know someone else with a PCS-80/30. It's definitely not comon (I had no idea what to offer for it) but I think it's great and am very happy with it. I had a scare or two with the video cutting out on the internal monitor but jiggling around some wires got it going. I also have an external composite looking jack that's wired in that I should try as well.

I'm almost positive my floppy problem is with the 12v regulator. I plugged the floppy drive into a SCSI enclosure for power and it worked. I got one read out of the floppy drive that had North Star DOS on it and that was it. I tried to format a floppy then verify it. It appeared to hang there so I restarted and haven't been able to read my one floppy since.

I'll have to figure out how to load North Star DOS through a serial connection so I can make a new disk. It's all part of the fun :) If you have issues, PM me too. I'm not sure I can help but two heads are better than one.