Nice work. I am sure you had a lot of fun, putting this back together. I had three of them that I was able to purchase all around the same time. So, I had a lot of fun putting them all back together.
Very clean inside, etc. Nice! But not counting the other options, Even the "real" IMSAI 8080 and the "real" Altair 8800 still had fake front panels. Those CPU chips didn't have enough pins to directly have the front panel lights and switches connected. What happened was that the "front panel" actually consisted of a ROM chip with tiny programs that input/output the front panel switches/lights to the CPU via the regular input/output lines. Nothing like the original PDP-8 etc, - especially the PDP-12 which was a GORGEOUS thing! - where the front panel switches and lights were directly connected to the circuits.
@@JohnHamerProjects I didn't specify where the ROM chip is, but reading through the IMSAI 8080 technical manuals "back in the day" I found the lists of the CPU instructions that were force-executed to display the registers on the LEDs etc. So it's happening somewhere, and what else could it be other than some kind of pre-programmed ROM?
The Imsaiguy and johns basement TH-cam channels go through how it works in pretty good detail. I am going to troubleshoot the examine switch not working in the next video and I'll try to go over it.
@@JohnHamerProjects The schematics were there too. How else could it work? There simply aren't CPU pins for the A register, for example. So it has to be displayed by CPU instructions, unlike the previously-mentioned PDP-8 etc. Take a look at the actual manual, dunfield.classiccmp.org/imsai/cpa.pdf at page 4-4, starting with the 3rd paragraph. Forcing the CPU to execute certain instructions is a form of read-only memory even if it's hard-wired with diodes or something.
I built mine in 1979. I still have it. You might want to think about replacing that big power supply with a new switching supply. If those are the original caps, they are getting very dry and will eventually fail. You should check to see if they are leaking from the bottom. You will see some brown junk on the chassis underneath the caps.
That's awesome! The caps don't show any signs of leaking, so I think I'm going to keep it original for now. I'll definitely keep an eye on them. Do you still have your IMSAI?
Also, the 8080 instruction set is really better oriented towards octal than hex. For machine-language use with the front panel lights/switches, it would make more sense for the switches to be color-grouped as 2 switches, then 3, then 3.
I'd love to have one of these. I've got a re-make of the Altair and a simulated clone of the IMSAI but it's not the same as having the real iron. BTW sound is only coming out the right channel.
@@JohnHamerProjects I've wanted one since 1976 when they first came to the computer shop down the road from where I lived. I thin it was like $600 CDN for the kit. My car cost less than that. One of these days..
I learned machine language/as language from an altair emulator program like 20 years ago when I was in college. That's what sparked my interest. The alrairs are so expensive. I might get a clone one day.
@@JohnHamerProjects These days you can re-build the Altair from new parts. Search for 'altair 8800c ". Of course there is also the clone for a lot less effort and money.
![บุษบา - เมนทอล [Official MV]](http://i.ytimg.com/vi/IGnWPokSEis/mqdefault.jpg)
Its really nice to see classic computer tech like this that is still working today!
It's amazing how well the ond stuff holds up if you take care of it.
It's really nice to see people tinker with and explore s100 stuff! looking forward to the next one!!
Thank you! Trying to get some other project done. An update on this should be it soon.
Nice work. I am sure you had a lot of fun, putting this back together. I had three of them that I was able to purchase all around the same time. So, I had a lot of fun putting them all back together.
Yes, I've wanted one for a long time. Just need some free time to troubleshoot the remaining issues
@@JohnHamerProjects Here is one of the videos that I made on my dueling IMSAIs. th-cam.com/video/Ny18-ArlS8U/w-d-xo.htmlfeature=shared
wow, amazing man! Thanks for sharing! really cool to watch!
Thanks for watching! Hopefully I will get some time to get the front panel fixed soon
Very clean inside, etc. Nice! But not counting the other options, Even the "real" IMSAI 8080 and the "real" Altair 8800 still had fake front panels. Those CPU chips didn't have enough pins to directly have the front panel lights and switches connected. What happened was that the "front panel" actually consisted of a ROM chip with tiny programs that input/output the front panel switches/lights to the CPU via the regular input/output lines.
Nothing like the original PDP-8 etc, - especially the PDP-12 which was a GORGEOUS thing! - where the front panel switches and lights were directly connected to the circuits.
It is an original Imsai 8080 front panel and there are no roms on it. The only reproduction board is the CPU board.
@@JohnHamerProjects I didn't specify where the ROM chip is, but reading through the IMSAI 8080 technical manuals "back in the day" I found the lists of the CPU instructions that were force-executed to display the registers on the LEDs etc. So it's happening somewhere, and what else could it be other than some kind of pre-programmed ROM?
Read the schematic. It makes sense.
The Imsaiguy and johns basement TH-cam channels go through how it works in pretty good detail. I am going to troubleshoot the examine switch not working in the next video and I'll try to go over it.
@@JohnHamerProjects The schematics were there too. How else could it work? There simply aren't CPU pins for the A register, for example. So it has to be displayed by CPU instructions, unlike the previously-mentioned PDP-8 etc. Take a look at the actual manual, dunfield.classiccmp.org/imsai/cpa.pdf at page 4-4, starting with the 3rd paragraph. Forcing the CPU to execute certain instructions is a form of read-only memory even if it's hard-wired with diodes or something.
I built mine in 1979. I still have it. You might want to think about replacing that big power supply with a new switching supply. If those are the original caps, they are getting very dry and will eventually fail. You should check to see if they are leaking from the bottom. You will see some brown junk on the chassis underneath the caps.
That's awesome! The caps don't show any signs of leaking, so I think I'm going to keep it original for now. I'll definitely keep an eye on them. Do you still have your IMSAI?
@@JohnHamerProjects - Yea, I do. I actually have 2 of them. One I picked up as a trade for a PET computer.
Also, the 8080 instruction set is really better oriented towards octal than hex. For machine-language use with the front panel lights/switches, it would make more sense for the switches to be color-grouped as 2 switches, then 3, then 3.
welcome to the party. my channel has lots of Imsai videos that may help you
Thanks! I've seen all your IMSAI videos. Big fan! Love chip of the day.
I'd love to have one of these. I've got a re-make of the Altair and a simulated clone of the IMSAI but it's not the same as having the real iron. BTW sound is only coming out the right channel.
Oh no! Thank you. New microphone
I've wanted one of these for a long time. I'm glad I finally pulled the trigger.
@@JohnHamerProjects I've wanted one since 1976 when they first came to the computer shop down the road from where I lived. I thin it was like $600 CDN for the kit. My car cost less than that. One of these days..
I learned machine language/as language from an altair emulator program like 20 years ago when I was in college. That's what sparked my interest. The alrairs are so expensive. I might get a clone one day.
@@JohnHamerProjects These days you can re-build the Altair from new parts. Search for 'altair 8800c ". Of course there is also the clone for a lot less effort and money.
Problem with your audio - left channel is completely silence.
Yeah, sorry about that. Didn't realize it until it was up for a while. I was using a new mic and had it in the wrong mode.