XT build day and after a good cleaning job some difficulties arose:

The case i got has no feet and i didn't notice so my desk got scratched.

So i improvised a quartet of feet with some antistatic foam:

A unusual problem arised, the screw supports for the power switch are too wide so i used the metal extensions in the old PSU that came with the case. The screws rub with one another but i managed to make it work.

Sitting on the desk wainting for the mobo:

Mobo in, XT-IDE with CF card 1GB partition with IBM PC-DOS 5.02. I/O/RTC and 16bit controller in as well:

Everything fine and PC timer retrieves time from the rtc card and sets DOS time:

I'm using an OAK 037C VGA. I found that my PVGA1 Paradise has some nasty image snow on some games, don't know if its hardware issue or not:

Swiched to CGA:

Testing Digger;

Sound card is a Sound Blaster Pro 2 CT1600 and PC Speaker is routed to it. I tried a CT1350B but these cards are way to noisy for my taste. I want an ATI Stereo FX for this build, provided i can find one.

A MIDIMAN MM-401 is also installed.

carlostex wrote:

No problem in sending you the BIOS. I doubt it will work though. It's this one. […]
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No problem in sending you the BIOS. I doubt it will work though. It's this one.

Your board seems to need a BIOS EVEN/ODD, those are probably 2 27C64 8kb EPROMS.

BTW, other BIOS'es work fine with my Juko board.

I would like to also find a 8086 board, but these are really hard to find. Usually 8086 systems were mostly OEM designs with stuff integrated in proprietary form factors. That sucks.

I'm hoping that someone designs a custom Turbo XT double or triple clock circuit. I already gave my idea to James Pearce from lo-tech and he liked the idea. With time i'm sure he will be able to pull it off. I would like to see a triple clock setting like 4.77/10/16 Mhz selectable. The 16Mhz would be only selectable if you have a V20/V30HL. I imagine a V20 at 16MHz could be close to a IBM 5170. And a V30 at 16Mhz could probably beat it.

Now about the build... The case i got from Kixs arrived today! Awesome case, it is close to perfect. It's a bit deep but fits my desk very well. I need to clean it and i will be putting the system together later today. Pictures to come as well.

The even/odd BIOS problem can be solved with by splitting your ROM image using a software utility.

Which BIOSes have you tried in your juko board so far? Did you try the CompuADD 810 BIOS?

My Juko 10MHz V30 board can already beat an 8MHz 5170. I would imagine at 16MHz it would be well into 12MHz 286 territory.

Anonymous Coward wrote:

The even/odd BIOS problem can be solved with by splitting your ROM image using a software utility.

Which BIOSes have you tried in your juko board so far? Did you try the CompuADD 810 BIOS?

My Juko 10MHz V30 board can already beat an 8MHz 5170. I would imagine at 16MHz it would be well into 12MHz 286 territory.

Never heard of that. how will the utility make a 16kb BIOS fit in a 8kb chip? Will the utility disassembly the BIOS and throw away half the code? Seems odd, have you tried this yourself?

I assume he means an utility that will create two 8kb ROM files out of a 16kb one, by putting even bytes on one and odd bytes on the other.

alexanrs wrote:

I assume he means an utility that will create two 8kb ROM files out of a 16kb one, by putting even bytes on one and odd bytes on the other.

Yes but i'm sure he'll understand that most 8088 boards are designed with a 2764 (8kb) in mind. I only have one 8088 board that supports a 16kb main ROM. It's this one:

https://th99.bl4ckb0x.de/m/E-H/30574.htm

Splitting a 16kb ROM BIOS for a board that is expecting an 8kb ROM won't work.

I wonder if one could simply remove the EEPROMs and put the BIOS in an ISA card mapped to the correct segment.

alexanrs wrote:

I wonder if one could simply remove the EEPROMs and put the BIOS in an ISA card mapped to the correct segment.

That might be possible.

dr.zeissler wrote:

I tested about 80 ISA graphics-cards on my 15" NEC-TFT and only a 3-5 produce a good and relatively sharp image on the TFT.
mostly there are vertical lines on greater spaces with the same color visable.

mostly "premium-manufactures" like diamond have better image-quality then no-name stuff with the same chipset.

I have a similar problem with monitor 17" TFT. This is vertical stripes and blur pixel in TEXT 80x25
Please, write me exactly what you managed to find a good videocard for TFT monitors?

Great thread.

I've had a couple of those cases and they're great to work with, but yes the way the mounting hardware protrudes sharply through the bottom can cause damage to whatever it's sitting on - up to and including my Commodore 128DCR 😒

That OAK display mode utility looks nicely implemented. I'm using a Trident 8900C in my 286 and have found the CGA mode to be excellent. I also have a Paradise card which works well in that system, but the image isn't "still". Each character in a screen of text, for example, will wobble slightly.

And yes regarding the CT1530B - I installed one recently and was amazed at how much "thinking" noise it produces. I was thrilled to own one back in the day but I've been spoilt since apparently.

Update on this machine!

I'm really happy with this build but there's always room for improvement:

Some people will advise you not to upgrade to a NEC V20 because it will muck up software timings in some games/programs. Unless you want to use your XT machine for 8088 demos that reqiure specific hardware (and the 8088 specifically along with it) i don't see any reason for not to upgrade. So far the amount of games plays absolutely fine, evem those that require 4.77MHz.

The NEC V20, because it includes a compatible 80186 instruction set, can run some software that you couldn't otherwise with a 8088/8086. One of them is GUEST.EXE, the iomega tool to search for the corresponding Iomega Zip drive and assign its proper driver. You can't do this with an 8088 and a Zip drive is in my opinion a great addition. Imagine that you do not have XT-IDE or a hard drive on your XT, you simply boot with a DOS floppy (DOS 5 at least required, but i still want to try Compaq 3.31) run guest and you'll be able to use a 100 or 250MB zip drive. Internal SCSI or Parallel port are the best choices for an XT with SCSI being rare and Parallel extremely common.

How about this? I tried running CP/M-86 from a Gotek, not really super useful but still cool that i can use some specific software for CP/M:

By the way the NEC V20 has another cool feature. Intel 8080 emulation! So i wonder if i can try regular CP/M (meant for 8080 machines), provided i can find disk images of course.

I also have been trying running PC Booters with the Gotek floppy emulator and so far i cannot complain. There are a lot of games that work, those who do not i suspect due to physical copy protections or requiring IBM CGA. I'll leave some screenshots but this will deserve its own thread later, as soon as i finish the spreadsheet file. Some screenshots:

Some titles have unsual formats like 10 sectors per track. So i used a different tool:

Unfortunately titles like Digger, Alley Cat and M.U.L.E. are not working. Digger never boots, Alley Cat hangs during Loading Alley Cat message and M.U.L.E. boots to the intro screen but the system restarts immediately. BTW, before someone screams abandonware, all the disk images i got was from the Internet Archive.

There are still a lot of titles missing, like the booter version of Paratrooper that i couldn't find anywhere else. I was told i should find a mirror for the Retrograde Station, but everything seems to be down. This shall be continued in its own thread. 😎

I know you could at least extract Digger and Alley Cat as COM files and run them from DOS.

alexanrs wrote:

I know you could at least extract Digger and Alley Cat as EXE files and run them from DOS.

There are tons of DOS conversions from booters, but the point was to have those booters run as booters from a Gotek.

carlostex wrote:

The NEC V20, because it includes a compatible 80186 instruction set, can run some software that you couldn't otherwise with a 8088/8086. One of them is GUEST.EXE, the iomega tool to search for the corresponding Iomega Zip drive and assign its proper driver. You can't do this with an 8088 and a Zip drive is in my opinion a great addition. Imagine that you do not have XT-IDE or a hard drive on your XT, you simply boot with a DOS floppy (DOS 5 at least required, but i still want to try Compaq 3.31) run guest and you'll be able to use a 100 or 250MB zip drive. Internal SCSI or Parallel port are the best choices for an XT with SCSI being rare and Parallel extremely common.

How about this? I tried running CP/M-86 from a Gotek, not really super useful but still cool that i can use some specific software for CP/M:

By the way the NEC V20 has another cool feature. Intel 8080 emulation! So i wonder if i can try regular CP/M (meant for 8080 machines), provided i can find disk images of course.

Re Zip drive: There is a 3rd party driver called palmZIP which supports a parallel zip drive and runs on an 8088. Not freeware, though.

Re CP/M-86: You might also be interested in Digital Research DOS Plus which combines MS-DOS and CP/M-86 support. (Not sure how compatible it is.) If you interested in this you can look for the floppy images for the Amstrad PC1512.
Re 8080 emulation: This is not as useful as it sounds since most CP/M software is compiled for Z80 which has additional instruction, and the V20 can't trap illegal instructions to emulate them. There are CP/M emulators for V20/V30 which can use this feature. You can't use any CP/M disk images since those would be machine specific. (CP/M runs on 8080 or Z80, but doesn't specify most of the hardware.) Also you probably could only run serious applications (eg. Wordstar), most games would be too hardware specific, you need a machine emulator for those. Maybe it would be possible to run some old Infocom text adventures.

Thanks idspispopd for all the info.

Today i got an ATI Stereo F/X from a fellow Vogons member. I like these cards compared to Sound Blaster 2.0's, and while i did try the SB 2.0 and it gave me pretty much the same functionality as the ATI card i just simply cannont bear with the copious amount of noise the SB 2.0 delivers. Yuck.

Installing was not all smooth sailing. I couldn't read the EEPROM from this XT build, i suppose some conflict because everynow and then it would throw a checksum error so there was no way for me to condigure the card. I had to take it off and put it in my Socket 7 build. Same problem went to happen in my Socket 7 machine though, and soon enough i removed the PAS card, tried again and it started to work.

I decided to do one better. Configure the card and write to the EPROM and then dump to contents to a file. If someone wants the dump here it is, configured to port 220h, IRQ 7 :

So i programmed a new EEPROM and stored the original:

Working fine now, with my needed configuration.

It's a great sound card, had it in the form of the VGA Stereo/FX 😀
I like the background stamps 🤣 🤣 🤣

^I really liked the mod you did on the VGA Stereo F/X when you sold it!

BTW, i still left the SB Pro 2 in this build so i can route the PC Speaker through the Line In of the Stereo F/X. I wish there was a better way to do this for cards that do not have a PC Speaker header.

I really have to try the potentiometer mod on the PC Speaker.

the potentiometer mod is essential Carlos, no more deafening beeps and bops 😁

keropi wrote:

the potentiometer mod is essential Carlos, no more deafening beeps and bops 😁

I never done it, can you explain the process in more detail?

Well it's nothing special really , you need a logarithmic potentiometer (my tests showed 1K is a good value) and you just install it on the (+) wire of the speaker. As you know the potentiometer is just a variable resistor so just treat it as one .
You might need to extend the wire though so the potentiometer can be mounted somewhere that can be adjusted but that's a per case thing, just keep the wire short 😎

You can see in the following picture that I disconnected the input red wire going to the speaker and connected a (red) wire that goes over the SB card... I run it to the potentiometer input and then then take the potentiometer output and run it back to the speaker. Nothing fancy...

Thanks Leo!

As far as potentiometers go you think this one will do?