View Full Version : imsai 8080 found

September 21st, 2007, 07:55 AM
Well with any luck my new to me Imsai 8080 will be shippping to me today :)

It comes with a disk drive and terminal too which would have been a great deal. The sad thing is the guy is to old to lift the terminal and disk drive so I think he said he is going to junk it :(

He told me he is the original owner and has been trying to sell the old peice of junk since July. And get this he only wanted $200.00 I almost cried because he said he was just going to throw it away in the dump if I didn't want it.

so hopefully all goes well and I receive it in a week.

September 21st, 2007, 07:57 AM
Nice score!

See if you can find someone local to the guy to pick up the drive and terminal. Maybe they can ship it, maybe they can keep it, but either way it's not trashed.


September 21st, 2007, 08:04 AM
Yeah i tried asking UPS and FED x to pick it up for me but they wouldn't package it up.. I am lucky the guy packaged the imsai for me thou.

He has the manuals too but can't find them :(
He also has a see threw top where those rare? He forgot to box it thou so I might get it later.

I would pay shipping if someone could pick it up for me :)

September 21st, 2007, 08:28 AM
What do you think guys? Should we make relating stories like this one illegal? :rolleyes:

September 21st, 2007, 08:29 AM
Where is it located? Sometime you can talk the boss at a UPS store into going and getting the thing and boxing it up for you. Of course, you pay for the boxing service per their normal rates, and you need to offer the person a generous tip, but it can be worth it at times.

This wouldn't work at a UPS depot, but the UPS stores are usually franchised operations, and you can talk to a real person...explain your predicament and the unique nature of the device--you might have some luck...

September 21st, 2007, 10:29 AM
Most PakMails will do pickups as well - you can find a location at PakMail.com

Yeah, they're exhorbitant, as barythrin can attest to - they charged I think $50 to pack/ship a Tandy 1000SX I sold to him for I think $50!

But, PakMails usually do NOT charge for pickups, at least the two I;ve used near by house never charged me.


September 21st, 2007, 01:01 PM
I was wondering if this see thru case is original or not.
I read somewhere they only made so many of these.

http://img2.freeimagehosting.net/uploads/th.94b7551447.jpg (http://img2.freeimagehosting.net/image.php?94b7551447.jpg)

September 21st, 2007, 01:04 PM
What do you think guys? Should we make relating stories like this one illegal? :rolleyes:

Yeah - I think bragging about a $200 nicely-loaded Imsai is worth what?
a 30-day ban for unsportmanlike conduct?



Terry Yager
September 21st, 2007, 01:15 PM
I think we should regard this tale as an urban legend, like the '54 Vette with 7 miles on the OD that somebody somewhere found sitting in a barn and bought for $100.00.<BFG>


September 21st, 2007, 06:27 PM
I was wondering if this see thru case is original or not.
I used to own an IMSAI. It was a store demo and it had a Lucite cover. I'm pretty sure mine always had the clear cover on it. It believe it was so you could see the LEDs on the memory boards: green LEDs for access and red LEDs for write protect.

I read somewhere they only made so many of these.
That's true. But if you think about it, they only make so many of everything. :-P

October 1st, 2007, 03:50 PM
The imsai came in today.
Has anyone else seen one with the on/off button on back of the imsai in the video spot?
He gave me some paper work where this was a fix because some of the imsai's where getting interference with the on/off on front.
It came with a DCHAYES card in it which I am assuming is a modem?
He had a terminal for it which I assume must of hooked to serial? I was hoping for a video card that would hook to a TV set :(
I hope to go threw it check things out and just put the MPU back in and fire her up and see how it goes.
I could scan some of the paper work he gave me but I think it may be up online already.

October 1st, 2007, 03:55 PM
Hayes, yes, modem.

Terminal, yes, serial. Think I would try 300 baud, 7 bits, even parity, 2 stop bits for a first guess.

October 1st, 2007, 03:59 PM
That "reforming the caps thing" is just for the big power supply jobs, no? It have anything to do with the "tant" caps? I am getting good at firework shows, 2nd one went poof the other day. It was strange. Waited until about power up number 10 before the show started. My first one went poof on the first power up.

October 1st, 2007, 06:20 PM
Yes, the reforming the electrolytic capacitors/burning tantalum capacitors is not a myth! If the old machine has been in storage for many years, you are best to disassemble it and rebuild in pieces rather than power it on all at once.

Start by reforming the electrolytic capacitors with a variac. Test each board on another system on a bus extender because the old Tantalum capacitors have a nasty tendancy to burn/explode as well. I have seen this in person and it can be a nasty surprise! I am sure many others here have also seen this.

Best of luck!

Andrew Lynch

PS, for heavens sake, never test a new old machine with cover on! If you'll have problems, it is best to see them early and turn off the power BEFORE your machine burns up entirely!

PPS, thanks Terry for the pointers!

October 1st, 2007, 06:38 PM
Well, didn't really answer my question. The reforming process doesn't help tants, does it?

October 1st, 2007, 07:08 PM
In theory, tantalum capacitors should only explode if the voltage applied to them is reversed.

There isn't really enough "insides" to them to de-polarize and they certainly aren't going to dry out.

That being said, stranger things have happened. I can't say I've ever seen a tantalum cap "go nova" for any other reason.

nige the hippy
October 2nd, 2007, 02:29 AM
I have just has SO MANY shorted tants in old kit, it's the first thing I look for now, saves smoking power supplies.

October 2nd, 2007, 02:40 AM
Well, didn't really answer my question. The reforming process doesn't help tants, does it?

My fingers were going slower than my brain apparently.

I do not think you can reform a tantalum capacitor. I test any "new" board on the bus extender before plugging it directly into the S-100 bus. That way if the tantalum capacitors are going to burn up, I can watch them do it and turn off the power before the fire spreads to other components.

My understanding is that tantalum capacitors grow "whiskers" similar to tin whiskers which short out the plates of the capacitor. When voltage is applied after one has been sitting there unused for many years, the whiskers conduct and either 1) burn up or 2) fuse together into a conductor. If its the latter, since the tantalum capacitor is a filter (ie, across the power and ground rails), the amount of current it can conduct is quite high and causes the device to literally burn up or even burst into flames. This has happened to me on a number of occasions on both S-100 cards and disk drives. It is another good reason to wear safety glasses while working on old equipment.

Thanks and best of luck!

Andrew Lynch

October 2nd, 2007, 08:15 AM
Bummer those variacs are so pricey.
Maybe I will wait on firing it up for awile.

October 2nd, 2007, 09:06 AM
You can get a "good enough" variac for reforming old computer power supplies for about $50 on Ebay or by various internet sources. They are worth having for sure. Be sure to remove all active components before starting the reformation process.

You can also use a series of light bulbs in series to reform electrolytic capacitors as well using these techniques:


I prefer the variac approach personally as the build up gradient is much smoother.

Best of luck with your project.

Andrew Lynch

PS, whatever you do, do NOT just plug it in to see if it will "just work". You'll be sorry!