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Fully restoring a lucky NEC V20 Turbo XT ...

Fully restoring a lucky NEC V20 Turbo XT Computer! (Intel 8088 clone)

Jan 12, 2022

Happy 2022!! I hope everybody is starting good this new year! The first post of the year is going to be quite interesting I hope since we are bringing back to life a 34 years old computer! The material in this post actually took a bit of a time to be collected since I started the process back in May of 2021.

The NEC V20 was a fully compatible clone of the Intel 8088, praised for being more efficient than the original and a cheap upgrade option at the time. I will not expand too much on this here because it goes beyond the scope of the post, but here a couple of links to read about the history of this processor:

This machine was originally rescued from a e-waste pile, along a monitor that already have appeared in the blog, the Samsung MA2561, that was tested beforehand in this post: A Herculean Sunday!. The appearance of the machine was quite right, aside of rusty slot covers, so I storage it away hoping to be able to check it soon…. Well, if my memory serves me right, that wait was at least 8 years long.

Finally last year I pulled it out from the box and started to check it out. I was gladly surprise to find almost no damage aside rust in the slot covers and some scratches in the case, looks like this machine was not badly abuse until it ended collection dust in some place a bit damp before me finding in the e-waste pile. The mayor problem I encountered to open the case was a screw so rusted that it broke, no harm done removing that aside having to use a bigger tread screw in one particular hole.

Everything looked right, so I went and jumped to the pool and…

Well! As you can see in the video, the machine didn´t explode or generated magic smoke, but the computer was stuck in a boot loop, with a stuck sounding hard drive. That was not entirely unexpected since the age of everything.

Since I don´t have access to more fancy things, like a Compact Flash or SD XT-IDE ISA adapter, my only choice was to try to repair the hard disk or at least being able to boot the machine from the floppy drive.

That was the moment when I initially left this project for a bit, wanted to test out another retro machines in my collection, plus a lot of life things getting in the way. In the meanwhile I just keep learning more about this old machines from Adrian´s channel and others similar.

After seeing a video by Adrian in his Adrian’s Digital Basement channel (I highly recommend that channel if you are into retro computing stuff, I also recommend channels like LGR or Necrowave), where he explained how to revive this type of hard disk (Link here:, I went to check if I was able to do anything with mine. To my huge luck, the ST-238R hard drive of this machine was constructed with a part of the motor exposed in a way that allow me to dissemble that particular section without touching the rest of the drive.

That is not always the case, as you can see in this other example that I have in my possession, a ST-251, were that section is constructed in a much less user-friendly way. That drive is dead, but the plates and parts still move is you power it up, so it’s a nice piece for my shelf.

I did not take pictures when I removed the screws and bottom part of the ST-238R, was a bit nervous and forget to do it. But after removing the part, I used cheap a multipurpose spray, similar to WD40, that is used a lot and sell by MAC Lubricantes, and….

It worked!! The only side effect if my rescuing attempt was that the hard drive data ended being completely wiped out since the first thing it did after reviving was to ask for an initialization, but I was really surprised with the result! And to think that those drives were even sold with some bad sectors on them!

Once that was done I was able to confirm another issue with the machine, even with the hard disk not being stuck, the computer was still doing a boot loop without even trying the boot from a floppy.

By the end of 2021, the opportunity to jump back into this project appeared! I was already having an idea about how to potentially fix that problem, which I really hoped to work since if any of the chips were faulty… well, I really don´t have were to get any replacements, there are just none on the wild where I live.

So again, I rolled the dice and went to ensure that every socketed chip on the board was sitting correctly, after all this poor XT was tossed around for a long time.

And again… it worked!

The computer was happier again! It accepted to boot from a basic boot disk created with my 80286 (DOS 5.0), so was time to see if the hard drive was properly recognized and more importantly if was going to work.

The biggest obstacle in this new phase were the floppy disks, I only have a few 5 ¼ disks and they are quite used up, most of them with some bad sectors, and when you only have 360kb of capacity any bytes lost is an issue. Aside of the disks not being exactly reliable 100% of the time. I need to buy a few boxes of those disk if someday I have the money.

 But after copying some of the minimum files I need to one, I was able to run the debug command to re-initialize the drive, wanted to try that process again just in case. Again, I was glad to see that the drive was showing some of the information of my previous attempt, like the table with the fault sectors that I didn´t need to type in again.

After that, was time to run FDISK that worked without too much problem and… another small issue, DOS 5.0 FORMAT wasn´t happy with the XT machine and refused to work. So, Internet Archive to the rescue! I was able to find an image of a DOS 3.3 boot disk, which was happy to run.

So, wow! This old Seagate ST-238R was fully back to life! And more importantly, the NEC V20 Turbo XT was able to boot from its own hard drive!

I went ahead a copied a few programs, a very old version of WordStar, Banner, and Grand Prix! Aside of course, Check it! To be able to run some more diagnostics, benchmarks and detailed hardware information.

Not much to say about WordStar, aside... “Oh boy, I feel old now!” 

Banner is a program that I used a lot as a kid in the 80286, along an Epson Action Printer T1000. It was a bit funny in a way to test this program in a computer that was slower that the 80286 to do task like render the letters and preview!

I have already showed a bit of Grand Prix in my old post when I tested out the monitor, so nothing to add aside this one being officially the oldest computer that I have used to play a game!

Check it allowed to run a benchmarks for the processor, video card and hard disk. I was able to confirm what I was reading about how much faster was the V20 compared with the original 8088 when running at its full speed, a whopping 12 MHz! (or 4.77 if you need to run it slower, that pretty much match the original processor speed used in the benchmark).

The hard disk was better in some aspects, but worse in others, but not bad! 

And the Winbond MDA card ended fairing quite good also. 

The memory check when without any problems. I left it running for several cycles to be sure. 

So, here we have it! If I take the BIOS date like manufacturing date as a starting point this computer is going to be 34 years old this year! So amazing to able to fully restore this computer, that soon is going to be in route to its new home in Mendoza, of the “Fundación Amigos del Libro” for their computer museum.

But we have to thanks also to Lady Luck, why? Because a lot of conditions where meet to be able to get this result:

  • I was able to find this machine in an e-waste pile. With NEC V20 I think this was the second third XT class computer that I was able to put my hands on.

  • The machine was quite intact.

  • There was no Real Time Clock ISA card installed in the computer, so the bullet of the battery corrosion was avoided.

  • There was no faulty chips on the board.

  • The hard disk was only stuck due to a very long time of inactivity, but with a construction that allowed me to lubricate the mechanism. Double luck because the drive presented no other damages!

  • The floppy drive was in perfect working condition.

The only part I needed to change was the cooler of the PSU, since the original was about to die.

Sadly all history of the origins of this computer were lost, not tags or stickers and the data of the hard disk was lost when I fixed it.

So thanks for reading this post! This one is my longest so far if I´m correct, I hope to be able to keep restoring computers like this one. Hopefully in the future will have more equipment to do more professional videos, or at least I can dream.

See you all in the next one!

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