More to the story: ( A Happy Ending for most of the original working guts )
The motherboard and cards were all working however whoever stored this system over the years had it in a basement somewhere where it was exposed to humidity so there is oxidation on surfaces of steel and zinc coated parts.
The power supply also had rust on it in places, but unfortunately had to get butchered to use the original power switch and the power connection male/female at the rear of the computer case/power supply. There were secure torx screws holding it together and I took an electric metal grinder to the tops of these screws vs going out and buying the special torx screw driver with a security indent at center. With the screw tops ground off the power supply body was able to be opened and the inside guts carefully specifically cut to keep the power switch and the power connections, but remove the rest of the power supply guts.
BUT the motherboard was given to a friend of mine who has a similar IBM 5150 computer that needed a good working motherboard, so he did a swap and got it running on the board I gave him so even though the original case was used for this project as well as old butchered floppy drives that were oxidized, the main board and all the 8-bit cards that I had with it lives on where another had failed. In addition to this the video card was a CGA adapter and so he was very pleased to get this to have color display working with his 5150 as for he originally was using a green monochrome. So he had a CGA display that he was able to put to use with it with older games that were created with option for Monochrome or CGA color display.
The computer case also is not perfect condition it has some scuff marks to the white paint and a small dent on top in 1 corner. The Plastic face is also not museum quality and shows that this was a well used system back in its day as well as probably got bumped around in storage.
Also the guy who gave me this 5150 originally told me that the condition of receipt was that I couldn't just sell it on ebay as a classic. I had to modernize its internals using this case and he has checked in with me on its status. I get to keep this computer in the end, but it had to go through this conversion. But I also didn't just rip boards out of this system carelessly. I carefully removed all the internals and placed them into ESD bags and placed them into my closet for a short while. Then when another friend of mine heard what I was working on he asked me what i did with the original guts. I said I have all the boards wrapped up in storage in ESD bags. He asked how much i wanted for them offering $75 for all of them and i said that I can not sell the parts as for under the agreement from the friend who gave me this computer it could not be sold, BUT I can give you these parts for free and he rushed on over to my house to pick them all up and then he raced back home to marathon a rebuild on his old computer which I believe was also a 5150. He then called me up like 4 hours later saying it all works and thanks so much.
I have no control on if he decides to keep his rebuild or sells it, but I stuck to the agreement i had with the original owner who handed it my way when I was talking about modernizing a dinosaur, but also keeping its appearance as original as can be for the computer cabinet.
As far as the XT reference. I realized now that it was a typo. The 5150 came out before the XT looking at the wiki.
As far as the prices of the originals in good working condition and clean shape, I have seen them on ebay and looking back I wished that I never got rid of 5 complete IBM 8088 systems + an 8086 CPU system I had back in the mid 1990s that were given to me because they were getting thrown away. I assumed that so many were made and so many survived that it wasn't worth saving any and so I gave them away to others who wanted them. Back in the mid 1990s they were very easy to come by and so they weren't saved. That has likely lead to the prices we see today, because if they were saved there would be more than the demand and not the prices of today.
Do you intend to displace Rube Goldberg
Thanks for the laugh
Well I stated that there is a way to do it with a single relay.... with transistors, caps, diode, and resistors ( and a pot to adjust the high duration of the single pulse length ) to sense the ON/OFF original power switch state in which a single pulse could be given to a single relay that initiates a power on for both switched to ON or switched to OFF position. And all importantly the diode across the relay coil to protect the circuit from the high voltage spike from the magnetic field collapse of the coil when de-energized which without the diode it would send a high voltage spike to the relay driver circuit IC or Transistor and blow it very quickly. Using all relays in the design is the most rugged and simplistic. Looking back at my draft I posted I need to add 2 diodes to the relays that are driven by the original SW1 to avoid the high voltage spike from arc-ing the switch contacts. K3 and K4 dont have to worry about a diode added for each because there is no disruption in power to them, they are hit with the power from their associated capacitors and drain out completely so there is no field collapse issue for K3 and K4 like there is for K1 and K2 which without diodes across the coils would deteriorate the switch contacts from high voltage arc-ing.
