Computer Hope

Picked back up on this project to convert the guts of an 8088XT to modern after looking at it tucked off in the corner. While all other builds I have seen online have a modern alteration push button added & optical drives in plain view etc, I want to keep my IBM 5150 looking as original as it can for the PC Case as I can. There still will be modern ports at the rear of it though which will be the only visual indication that its not original and has been heavily modified to run modern guts internally. The two large 5.25" floppy drives are in the bays, however they have been since gutted and one floppy drives LED has been wired to the HDD while the other has been seriously modded to have a USB optical drive tucked behind the black plastic face and I still have to redirect the LED to the red LED of the 5.25" face. The motherboard is installed, and power supply altered to fit. Also formed PS2 connections for mouse/keyboard in a block of epoxy that hardened and was mounted where the Cassete/Keyboard connections were for this case. The PS2 male/female extension cables were used to do this as for the motherboard had to be installed 90 degrees out to fit with the PSU internally. I have it staged with a Pentium 4 mATX motherboard for now that is functional. I also redirected the VGA port of it to a bay slot with a VGA cable extender, and a metal slot bracket off of an old VGA video card to remove the board and screw the 2 stand offs into the extension on the bracket and make it look as if a video card is at this slot, since the motherboard is turned 90 degrees in the case. Tremendous amounts of metal work required to pull this off including taking a metal ban saw to the soft cast aluminum bodies of the old massive space wasting 5.25" floppy drives. The HDD actually fits perfect under the right most 5.25" bay where there is a space that works perfect for a single HDD installed and drilled a single hole through the formed 90 of the 5.25" bay frame to lock the HDD tight to. Also I gutted the original power supply for this old computer but left 1/2 of the power supply shell intact which holds the power connections to the outside world as well as the large red original power switch.

Decided to draw up a schematic to make the old red power switch on the side of the IBM 5150 8088XT case function for modern motherboards with momentary power switch requirements.

Here is a very rough draft of it performing a brain dump to MSPAINT to create since I dont own any cool circuit design software. And this is in reference to this project that I was working on a ways back as linked below.

http://www.computerhope.com/forum/index.php/topic,138922.0.html

Note:

I still have to perform all the math and decide which relays to use which have different current specs. The uF rating of the capacitors will be directly related to the coil current of relays K3 and K4 as for if they are too weak they will completely drain out the minute that they make connection to the coil and not cause the relay to energize, yet if they are rated too high of uF it will energize K3 or K4 for too long just as if you held your finger on a modern computers power button and this can lead to the motherboard taking this state as a hard shutdown initiated by the computer user. So I still have to put together the specs for the relays and capacitors. *Also to save some money, the relays K3 and K4 can be SPST, as for I have DPDT relays in my draft schematic that I attached. The DPDT relays are required for K1 and K2 as for 1/2 of each relay is used for charging C1 and C2 and the other 1/2 of the relay is used for its opposite state in which in its opposite state it sends C1 or C2 to K3 or K4 which then causes K3 or K4 to latch momentary the contact of K3 or K4 to simulate a soft power button push.

This circuit will create this momentary push button depression simulation as a 1 shot in both its ON and OFF state of SW1 switch.

Well off to www.mouser.com to look up the parts I need and order them up, and then solder it all up, and then reply back here at some point with part numbers and values I used in case anyone else ever wants to make a simulated momentary power switch for use with an old computer case and modern guts like I am doing. Also the use of relays in this design is mainly because its the cleanest way to control the motherboard with isolation between the momentary push button switch simulator circuit and the power source that drives this circuit. You definately do not want to be accidentally feeding power such as 12VDC into the power switch pins of a motherboard for example.

***Lastly this circuit could also be made with a single relay with transistors or chip(s) to function the K1 and K2 logic/redirection to a K3 with K4 removed, as well as add a potentiometer to adjust the simulated push button hold in time to be as if a virtual finger held it pushed in for shorter or longer period of time, but I didnt go that far in this design process because why overcomplicate it. 



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Sounds like a neat project but you mentioned several times that it's a IBM 5150 and other times you say it's an 8088XT.  Which is it?  The model 5150 is the original IBM PC but it is not an XT.  The XT's model number is the 5160.  Both used the 8088 cpu, the main difference was that the 5150 had a motherboard with 5 expansion slots while the 5160 had 8 expansion slots.  The 5160 had a larger power supply (135W) while the 5150 had a smaller (63W) power supply.  The larger power supply was needed to provide power for the extra cards expansion cards but the 5160 could also be had with a hard drive while the 5150 did not support a hard drive.

I hope the machine you are doing this to was non-functioning and that you didn't tear apart a working 5150 or 5160 for this project.

Got any pics?

Quote from: strollin on March 01, 2014, 08:59:11 PM
Sounds like a neat project but you mentioned several times that it's a IBM 5150 and other times you say it's an 8088XT.  Which is it?  The model 5150 is the original IBM PC but it is not an XT.  The XT's model number is the 51560.  Both used the 8088 cpu, the main difference was that the 5150 had a motherboard with 5 expansion slots while the 5160 had 8 expansion slots.  The 5160 had a larger power supply (135W) while the 5150 had a smaller (63W) power supply.  The larger power supply was needed to provide power for the extra cards expansion cards but the 5160 could also be had with a hard drive while the 5150 did not support a hard drive.

I think the "XT" is a typo. the original thread makes no mention of anything being an XT

Quote
I hope the machine you are doing this to was non-functioning and that you didn't tear apart a working 5150 or 5160 for this project.

From the other thread:

Quote
As far as this 5150 goes the deal with getting it for free from him was that I would bring it through the conversion process and document it for him. I get to keep the computer as my own. So this box cant be saved. Its not in mint condition. I am planning on saving the guts though since they probably work. I have a collection of old guts in my closet in ESD bags. So if I find another 5150 with say just 512k RAM and want to max it out to 640k, I can grab RAM chips out of it etc for the extra 128k.

So it sounds like it was working... but the stipulation of receiving it was that he would gut it, or something. I still think it's a bit of a shame, would be better if the system had failed components for example.

I am lost. You are using three relays to generate a pulse?
So the objective to see have many relays it takes?
Do you intend to displace  Rube Goldberg
http://en.wikipedia.org/wiki/Rube_Goldberg

What is the turn off time for a normal push button?
What is the restart time for modern normal push button?

As others have said, as someone who has restored an original XT back to working condition which took days of work and a large amount of money (See attatched photo), I really hope the 5150 was completely dead and therefore worthless.  Otherwise you have taken what was a very valuable computer and basically destroyed all of its value.

I'd pay quite a decent amount for a new top cover for my XT as my current one is very badly beaten up - I wouldn't dream of cutting this machine up to turn what is currently a very historically significant machine into a boring, common PC that will be obsolete in a couple of years.

I also guess you haven't checked the prices on eBay for those full height 5.25" floppy drives you "gutted" - Those things are rare and, in working condition are worth a lot - Likely more than the components you are putting in the XT's case!

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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.

QuoteDo 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.

Update on this project:

Here is the computer to see it run with staged guts. Later I plan on putting more than just a Pentium 4 and 300 watt PSU in it, but for now, this is what i was able to do with parts on hand. Swapping out the motherboard will be easy as cake since its set up to mATX mounting.Swapping out the power supply and getting that to fit with a higher wattage such as a 500 watt might take some more modifications.

https://www.youtube.com/watch?v=pP5_Ihf-rhg

Decided to name the Project Altered Beast along the way, since the more I worked on this to alter it, the more it fought me along the way and so I started tallking it the beast and a friend of mine said you should call it Altered Beast like the old video game, so that stuck with it. It took a lot of work and tight measurements with placement of certain components.

Originally I didnt want to have a momentary push button as the power button, but I decided to get some push button switches from Radio Shack because their appearance didnt give it any modern look.

Two locations in this case worked out perfect without modification.

- 3.5" HDD fit perfect in a space under the right side 5.25" bay. Just needed to drill a single hole in a tab that secures the 5.25" bay frame and then use that single screw to lock the HDD in place from moving.

- Laptop DVD-Rom fit perfect in the gutted 5.25" drive compartment. All I had to do was line it up with the 5.25" floppy slot and then hot glue it into place.

Everywhere else required modifications, some of them with tight tolerances to get parts to clear.

Parts on order to complete this beyond what you see here:

- 4 port USB 2.0 bracket with cables
- Audio 5.1 bracket with cable

Then someday later on I may make the toggle switch functional as a momentary with the circuit mod that i drew up to make a toggle switch function to the motherboard as a momentary connection.

Nice job.

I really like how you mounted the optical drive using the 5 1/4" floppy faceplate, very cool.