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Because the board I bought is an exact replica of the original 16k MCS board. Are you saying I can substitute the 4200s with cmos chips?

I'll check for any shorts on the motherboard a bit later today or possibly tomorrow, but as for borrowing a memory board from someone, I'll have to do some digging. The old MITS building where the Altair 8800s were built and shipped from is just down the street from where I live here in...

The capacitors are new. Every component on the PS board is new in fact. I bought a replica board from Klyball a while back and added the components myself. The 8800 CPU board I built myself from a replica bare board that I ordered on Ebay as well as I did not have one and the original board that...

Hello again, So a few years on down the line, and I'm still working on my Altair 8800 in my spare time, and I've been able to fix all the issues I've had with it except for one which frankly has stumped me for quite some time. I have a theory about it that I was hoping someone can confirm for...

Hello, I am in need of some photos of the Altair 8800's power supply board as I can't seem to find any online. Specifically the bottom side. I have a few broken traces I need to fix, and the foil is completely gone on the board in a couple places. I don't want to bother with using the schematic...

Yep!! the diodes all check out ok :) Here are a couple pictures of the transformers. the shiny silver one that says Radio shack is the new one i replaced the old one with. They are in the exact same formation as shown in the assembly manual in way of mounting so i do believe i replaced T2. I...

I followed the manual for putting the components in, and i AM sure i was measuring R4 because it was printed R4 right above it on the board itself. These are the pages i followed step by step for doing everything i did when putting the Altair back together and hooking it up. And this...

If the R4 you're talking about is resistor 4 then no, I don't think it is hooked up correctly. with the meter it shows a steady 4.6 ohms on the +18v line. When i put my leads on R4 and the -18v line it starts really low and just keeps climbing. As for your comment, "Also, what You are showing...

Marty, when i took those voltage measurements, there were no boards plugged in, and no load on the unit. I did check the surrounding pins, and there doesnt seem to be any leakage. as for the PS board being wired correctly, it appears to be. Although i have found that there is an added something...

I have a Commodore SX-64 that I am testing, and on startup the usual boot screen appears and then says READY. But then it automatically starts typing weird text. I don't know if it's gibberish or not. What might be causing this? Also how can I fix it. It does it with or without the keyboard...

Got the wires fixed, and they are as they should be now, Below is a picture showing exactly how i set the board up which is for the first 4k block. Also since you mentioned that it might be automatically jumping to the Eprom memory, what would happen if I took the Eprom chip out? Because...

Here's the last picture showing what i was talking about with my wiring for my data lines. For some reason it only lets you post 5 photos per post. The reason the other wires are cut off is because i don't think i need them. it seems that in a z80 CPU board manual similar to my own it shows the...

Marty, I think my data wires are wired right. Reading the labels on the front of the display/control board where the wires connect, D7 is blue, D6 is yellow, D5 is red, D4 is black, D3 is grey, D2 is dark blue, D1 is the second yellow on my cable, and D0 is the second red. As i show in one of my...

Hi, I finally wired up my Altair 8800 and put a California Computer Systems Z80 Model 2810 CPU board in it, as well as an S.D. Sales/Systems 4K Low power static RAM board in it. I then hooked up the display/control board, and fired it up. Well... The CPU boards Interrupt light is on as well as...

Hi, I have a commodore plus 4 that i am having some issues with and was wondering if anyone could help me out. the unit powers on and i have video the purple ring around the screen is there but there is no message saying commodore basic and i cannot type anything, it shows this screen picture...

hi i cant seem to figure out how to save a database file to a floppy disk any help? k1atn

i am having trouble finding switching power supplies to power the Altair 8800. grant stockly said he had put an 8v 100 watt switching power supply and a +16v/-16v/5v 60W switching power supply in his kit, but i cannot find ANY switching power supplies WHATSOEVER on the net with those specs. if...

i have an Amiga 500, but am having problems reading disks. i have workbench 1.2 on it and some games and data disks run fine, like lemmings, but other disks i put in, game or not, the screen goes blank then it goes back to the workbench 1.2 screen and nothing happens. i tried to load workbench...

Hi, I have a 2716 eprom chip and i want to put a certain program on it. According to my model 2810 z-80 CPU cards manual, in order to use the monitor part of my card, i need a program called MOSS 2.2 Monitor, on the cards on board ROM, but i don't have a ROM chip in it. so i have a blank 2716...

i don't know if they make it, but i was wondering if anyone online or otherwise makes a stencil to repaint the words on the faceplate that have worn off due to age, also if anyone sells authentic altair paint to repaint the case with original colors. thanks k1atn