KICK FOR EASY UPDATING

Little update.

I hasitated alot if i want to keep this systeem in this case.
But now i havent any choice anymore.. Because my system is lacking ISA slots.
With my old case i could only use 6 ISA cards in it and a little spare card that dont have to use the bracket` s slot.
Actually the PSU is covering 1 / 1/2 slot. (motherboard have 8 ISA 8-bit slots)

I want to add an Roland MPU- IPC-T midi interface card to connect the Roland MT32 (old style version) on it.
And the other slot i what to use with an EMS memory board in it so i could run windows 3.0 as well.
I dont want to remove my Serial / LPT card (because then it doesnt have connection ports on the computer..

I also making the final steps to finish my first project V20 Retro NEC turbo computer..
I am not really out which case iam finially going to use.. But my sense have already make a litte dicision. But that guys will you see later.

Notice

Last things do to:

Rebuild the system in a other case with full 8 bracket places.
Find a 5,25 inch floppy drive 1.2 MB and mount it
Thinking of using a backup medium
Placing a roland MPU interface in it. and connecting an Roland MT-32 on it.
Hope to found a CO-processor as well to finish this build.

Thinking of reinstall the system with MS-DOS 5.0A (dont know for sure)

oh very nice! I did not know about the y2k update to the bios part! I'm going to have to harass chuck about it for my build.

Yeah its a nice idea (that y2K RTC) Otherwise the computer doesnt have one RTC.. Older ones on multifunction cards doesnt works( i think they wont going over the year 2000)

A month or so i bought a nec d70108hcz-16. It should be a high clocked V20HL processor AT 16Mhz..
Should i use it for this build? Iam only a little bit affraid that the simple dos games (that doesnt accept high speeds) should have i problem..

When i shut the turbo off, shall this processor run on the same speed as a normal V20? Or would a V20HL only give me benefit on turbo switched speed?

its only rated for that speed. it will work only as fast as the motherboard will allow it. its like putting a 386-40 into a 386-33 board.

Maybe you can build a clock doubling circuit.

I can almost complete this system.. Ive found a new case for it thanks to fabian from amoretro.. I found this case on ebay, because i dont have much resources to look for an other case.. It seems that retro gaming is likely `big bang`.. Also in my country.. So its hard to find a good usable case.. I like the desktops for this systeem, because tower models uses sliding motherboard spacers. But cant use them on the ST juko clone motherboards.
Because the motherboard then can use only one screw on the back of the case, so the board wont sitting sturdy in the case.. I prefer more the screwable motherboard spacers. Because they sitting good tight on the moterboard tray plate.. Then the board cant move anymore.. I also looked on 2ehand sites in my own country, but the AT cases are very RARE limited.. And i dont like to wait for 4 years for a usable case..
So i just bought a complete system from amoretro.. Then definitely iam going to use that case for my XT NEC V20 systeem..

Its a good looking case, only the buttons are yellowed.. Hopefully can solve this with that whiter stuff (retro bright) Otherwise iam going it spraying it black or so.

The second is, that in the mean time ive bought 2 copy replacement motherboard.. If one would unrepairable, i can always use a spare one. The second and the third board i need to test it for working.. When they working i leave them as spares..

The new case having 8 slots brackets, so now i can use them all.. Giving me the possibility to use all the 8 slots on the motherboard, and giving me some space for the intel above memory board i want to use in this machine.

What i also have to do is, to replace the jumper pins for reset, keylock, turbo button ect for all the three boards to 90 degrees angled ones.. Because otherwise it would give problems when installing large isa cards on the motherboard. Now i only have to wait when the case arrives.. But that could take some days..

And the new case i received this saterday the 28-09-2013..

Some pictures here:

Iam very happy with finding this case, i needed a desktop specially for the ST juko clone boards to mount in.(because of the mounting holes) But AT desktops here are very hard to get, so i thought it would better to buy a whole system with a good looking case and some parts i could use later when needed.
This system when received have to following specs:

386 motherboard with DX 33 processor
8x 1MB memory from siemens.
230MB SCSI harddisk
Adaptec 16-bit SCSi controller
MAD16 soundcard (worst soundcard i ever have heard(have a lot of background noise)
Mitsumi FX001DE 2 speed cd-rom
1.44MB floppy drive
Teac 1.2MB floppy drive.
TSeng lab 1MB graphics card.

What iam now going to do:

Recently i have bought some spare replacement boards for my NEC V20 system:

But they doesnt work good as supposed to.. They have weird behavings.. So iam hopely going the solve it to good working motherboards.
The first came with a Erso bios (its a little worser then the flytek ST-12 one)
The second one came with a 8088 bios.. So it could only regonize the first 640KB when installing 1024KB of memory. I think to replace both bioses with a copy of the flytek ST-12 bios from the working motherboard..(just write 2 new eproms.

Then iam going to replace the jumper pins on those boards to 90 degrees angled ones. Because when installing larger ISA boards the vertical jumpers could make problems with installing the isa boards..
And think of replace the memory on those board.. Its old stuff so it cant garantee the memory would still life longer then what i thought off.

If i have to other boards working i go further on building this system. This because i need to remove the flytek ST-12 bios.. And that easier when the board is out of the case. Otherwise i still have to disamble it..

I have already fixed those two boards.. Given them two new eproms with the current ST-JUKO bios from the first fly-tek motherboard.

Iam waiting on angled pin headers to replace the stock ones for angled ones..
And have to buy some memory for that other board..

Iam also thinking of buying a 50watt solder iron for my weller WSD-80 solder station.
And iam also looking for a de-solder station / iron.

Then could do the solder job a lot more easier and quicker.

I have a really bad feeling on the moment!.. Tried to desolder the pin headers of one off my spare juko ST motherboards..

But never thought the quality of those motherboards are just to cry.. Never saw a cheap build quality like these clone motherboard..

What happend.. Tried to desolder the pin headers of one of the motherboards. But the electonic traces went loose .Ive already disambled all pin headers (turbo led, power led ect) they are off now.. But on three places the traces are damaged and only can repair it with thin electronic wire..
To solder these on the board isnt very easy.. On bigger solder spots its a piece of cake. But i have also two little tiny ones.. i dont think the wire would attach to the smaller points because of to litte spot to hold on..

I think iam going scrap my plans off solder angle pin headers on the board.. Better to solder a dupont wire on the existing pin header.
Never thought the quality would have been that bad!

So my thoughs, never solder bad quality boards again!

[

Today my second Kouwell KW-530D HD floppy disk controller arrived.. I was very happy to know that this bios should be the one for my first card.. I swapped the rom out and it came to live.. So i have solved the
Kouwell bios problem in the first post.

Now i only need to find the right eprom to write the code to it.

post a picture

woot woot!

a bios programmer is a good investment for us. Seems to pay for themselves real quick. I know I've revived at least 3 boards with mine.

Thats why i have a programmer and UV-eraser here.. Yes it pays you really off.. Not every piece of hardware i get arent come without problems.. In this case someone else tried to recover the eprom, but i guess he thought it would be a scsi controller (it came with that scsi bios). I knew that back in those days this was a HD floppy controller, specially for XT style computers to give them 1.44MB and 1.2MB support..
But iam happy that waiting may could pays off.

Does anybody know which type EEPROM is compatible with that SEEQ DQ28C64? Would an other 28C64 would do fine? I tried it to write this code on a Texas intruments 2764-20JL i had, but it doesnt seems to work (gave me an write error on a specific line in the eprom.) I guess i need a CMOS one for it? So a regular 28C64 would do?

thats my guess. I've been told you can use larger chips, (128k etc) so long as you zero everything after the data. Also as long as the chip has the same pinout. its like converting a 720kb floppy image to 1.44.

I didnt used a larger chip for it, because i dont see the meaning of it, if the code should fit on a 64K as well (the bios code for these devices never get over 64KB). But i tried to zero everything (instead of FF FF) after the data, but the writing to the eprom didnt work as aspected. I just think maybe i used the wrong type of chip.. I also tried to empty it for 20min in the eraser, but didnt work actually.

it might actually fit in a 32k... Also FF is not zero. and experience has taught me it takes ~1 hour to blank a windowed eeprom.

Iam back again on this system. Iam really hope that i can end it soon.. Some good news and some bad news. I thought again, which AT case iam wanted to use on which system. (That every system have its own unique case that fitts to the system)
On the new case i got for this system lately, thought if it would be a good idea to use it for my XT build. On the other hand, i really loved it to put my 386 system in a desktop case also ( So just leave it as i bought it from ebay. I generally liked it how it was) ( Previously my first 386 build, i had the system in a giant big tower but i prefer having it on the desktop case)

I also had some few problems with the LED display and the XT board, because i want to set the stock speed to 4.77mhz ( but i couldnt managed to set the dot on the display) I thought that the XT board in this new case isnt really what i wanted. About some months ago i keeping my eyes on a case thats really fitts my XT build.. I know finding an XT JUKO electronics case these days is just almost impossible.
So i really needed to make a big decision here. So it was anything or nothing..

The Bad news is.. It costs me some freakin money. Maybe there are people also have seen this case.. But after paying, the good news is: fortunately i can end this system soon.. And got rid of that turbo display now. Have enough space the add a second harddisk = more space finally). All i have to do is stripping it and give it a good cleaning, and i want to give it a paint job.. The other good news is that this case also have an Juko ST board inside.. When to case is ready i would put my own hardware in.

This would be my final case:

Some update for now.. (hardware is for 99% done) Keep struggle to get the right case)

Iam trying to get this project done.. Its already few years later as we are now in 2017... I decided with the last bought case (few post above here) that it was a better idea to use that case for my 286 system, because it looked more period correct.. and i did not had a case for the 286 project that time.

Then again i bought a new case for this system, which gave me a headache.. It wasnt very hard for me to replace the rubber feets underneath it.. But i have had a paint job problem.. (cause iam still struggle with it)
(hard to find the matching paint, i had not idea which technique they used back in the day.)

The underside was verily damaged (rust spots) which made me concerns how long it would take to would it be much worser.. So i really wanted to paint it (wanted to keep the original paint on the sides and the upper part) and only wanted to paint the bottom.. Iam not really an expert in paint, so it was very hard to find the right paint for the job.

The paint needs to be scratch resistant. No easy to got it off, and also match with the rest of original paint. I found a can and started painting (after i sanded it an removed the dust and other particulars.)

And few hours it dried.. But iam not really happy with the result. Its looks off with the original paint.. And some of the new paint was getting on the bottom sides.. I have to re-done this.. But iam thinking to Powder coat the whole base frame..

Second problem is the button / computer indicator light plastic front frame is yellowed. Try to getting a clean look.. There is a thin plastic sheet on it (iam guessing the glue underneath it make that thing looks yellowed.
This all consumes to much time.. Decided to look for another case.. So this IBM XT clone case showed up:

I hope when everything will went will, i only would have to clean this case and mount the hardware parts inside.

I have also in the time i wasnt present here found an second Juko V20 motherboard, luckily it came with the original manual and a 5.25 floppy driver disk..

Robin4 wrote:

I have also in the time i wasnt present here found an second Juko V20 motherboard, luckily it came with the original manual and a 5.25 floppy driver disk..

Do you mind uploading the manual and the disk?