The XT motherboard came with 640K RAM and an NEC V20 chip, and an empty socket where the 8087 math coprocessor fits (I hope to get one for this soon...I may have one in one of my Tandy 1000's that I could test).

Overall, the board was in great shape, but kept giving me a "Bad Keyboard" error when I originally tested it. Damn...I almost forgot that I needed an XT compatible keyboard! Well, I went into my stash of old retro gear and found one of my IBM Model M's. I heard that those sometimes work on XT's, so I gave it a try. Well I still got the bad keyboard error. Then I remembered reading somewhere here on Vogons that the keylock circuit sometimes has reverse logic and will unlock the keyboard only if the keylock is locked not unlocked (or I could have just shorted the jumper pin too), but either way, I used a screwdriver to turn the keylock on and voila! the keyboard worked! So whoever it was here on Vogons that mentioned the thing about reverse logic...thanks.

Anyways, as I mentioned I cleaned my 'new' case piece by piece. After all, it wasn't in perfect shape and had some fine scratches and black marks everywhere and it was a bit yellow. I did a bit of retrobright treatment on the front plastic part using my bottle of hair developer and also cleaned everything with a mr. clean magic eraser and soap and water and . I also removed all the stickers from the back of it. I prefer the plain steel look without all the homemade labels and manufacturer label and such (unless it's an OEM system). I still need to find a case badge, but I'm thinking I might just make one. But all in all, it looks pretty good I think.

Moving on, I took apart the power supply and was surprised to not find much dust in there, so I just gave it a little compressed gas treatment, cleaned the chrome metal and moved on to install the P/S back in the case.

Then I installed the motherboard with plastic and two metal standoffs.

After, I installed the Seagate ST-238-R MFM hard drive in the bottom of the 3 5.25" bay (the internal one, leaving 2 5.25" bays open) and hooked up all the cables to the 8 bit controller.

I did the same with an old Chinon 5.25" FDD I had and hooked that up to the 8 bit FDD controller.

I did some initial tests using an old OAK 16-bit VGA card that worked in the 8 bit slot and everything booted fine into DOS 6.0 and the turbo function works great! I tried a couple games already and there is a noticeable slowdown and speedup "on the fly" as I switched the turbo on and off.

So that's as far as I got so far and will be working on it more in the next couple of weeks I hope.

I will keep posting my progress here and hope to have this done soon.

My plans for it include:
- installing a color matched 3.5" FDD
- installing my adlib soundcard for sound and maybe another soundcard (SB maybe?) ....anyone have any suggestions?
- installing a Roland MPU-401 intelligent interface card for MIDI sound
- maybe one day down the road investing the time and money into XT-IDE solution
- adjusting jumpers on LED readout to show "8" and "4.7"
- getting an 8088 coprocessor
- testing various CGA and EGA cards as I want to use this system exclusively in CGA and/or EGA and not VGA

I don't want to go too crazy with upgrades as I will want to keep this XT build for games of the CGA and EGA genre. For newer DOS games, I will use my 286 up to P4 systems.

Here are some more pics...(not too interesting)

the back of the case, with and without the stickers and homemade labels...

Other pics...

More pictures to come including testing on CGA / EGA monitor and with 3.5" FDD and soundcard(s) and other parts installed...Thanks for looking.

Wow that case looks almost brand new by the time you're done with it!

What are all those empty sockets on the XT motherboard, apart from the copro one? It almost looks like you can plug expansion ROMs directly onto the motherboard? That would be an interesting/handy feature if it were possible!

very nice!
it seems late 2015 is becoming the XT year 🤣 🤣 🤣

No doubt, seems like 30 years after XT clones exploded they're exploding again. (in our small community at least)

keropi wrote:

very nice!
it seems late 2015 is becoming the XT year 🤣 🤣 🤣

🤣 very true! I actually have been looking to build a decent XT machine for many years now, it just happened that it was now during the '2015 Vogons XT Renaissance' 🤣 🤣

@keropi - I really like how your Acer 500+ XT system is turning out BTW, that's an awesome setup so far!

Malvineous wrote:

Wow that case looks almost brand new by the time you're done with it!

Yeah, I'm happy with how it turned out so far. I'm going to put a lot of effort into cable management as well, so it should look good inside and out when I'm all done.

Malvineous wrote:

What are all those empty sockets on the XT motherboard, apart from the copro one? It almost looks like you can plug expansion ROMs directly onto the motherboard? That would be an interesting/handy feature if it were possible!

Those sockets are certainly for some sort of ROMs but I am not sure for what exactly. If anyone can shed some light on this, it would be much appreciated.

retrofanatic wrote:

Those sockets are certainly for some sort of ROMs but I am not sure for what exactly. If anyone can shed some light on this, it would be much appreciated.

If my calculations are correct, then 640kB conventional memory will sit between segments 0000 and 9000. Expansion ROMs were designed to sit above this, so that would put the start of this area at A000. Your board has six sockets, which could put them at A000, B000, C000, D000, E000 and F000. The last one has a chip in it, and since the BIOS normally sits at F000, this would appear to make sense.

So in theory if you got a 64kB ROM and stuck it in the first slot, its contents would appear at A000. Interesting!

I wonder whether you could flash DOS onto an EEPROM and put it in there so you could boot the machine entirely from ROM? It looks like you might only have D000 and E000 to play with as the other segments are used by the video card (except for CGA/MDA which doesn't use A000), so I guess it depends on whether you can fit everything DOS needs to boot into 128kB.

Man, retrofanatic you always do such a good job cleaning up your cases. I start off with good intentions but get to excited about getting he thing up and running.
I totally get wanting to keep your stack nice and tidy. part of me wants a nice clean line of similar cases with, part of me likes having different cases for different reasons, again I couldn't wait knowing I have a perfectly good system in storage just cause of the case.

Regarding the soundcard, there is no need IMHO to install both an AdLib and a SB... just install a 8bit SB and you'll have AdLib working too. I will be using a CT1320C with CMS chips with my XT.
Midi is a plus , you need an mpu in there! 😁
Also totally agree on the CGA/EGA decision, vga is nice but we have a billion other systems that are vga-capable. I'll be sticking to the IBM CGA I got for my XT build.

keropi wrote:

Regarding the soundcard, there is no need IMHO to install both an AdLib and a SB...

I don't think it's even possible, because they both have an OPL2-chip fixed at address 388h, so you'd get a conflict.

Scali wrote:

I don't think it's even possible, because they both have an OPL2-chip fixed at address 388h, so you'd get a conflict.

In practice, having multiples of the same OPL type in a system doesn't really present much of a conflict. There's the duplication of FM sound from the similarly-addressed cards to deal with, which some folks seem to find desirable, but not much of a read component to be concerned with otherwise.

Scali wrote:

I don't think it's even possible, because they both have an OPL2-chip fixed at address 388h, so you'd get a conflict.

AFAIK it is possible because the cards just "listen" to the address. So both cards will play at the same time. I'm not sure but it is a benefit of how the original AdLib was designed.

Sound Blasters do hog their other base addresses like 220h, so if another card is placed there it will conflict. Creative probably did this on purpose. OPL chips on Sound Blasters can be accessed from their base ports as well.

Malvineous wrote:

If my calculations are correct, then 640kB conventional memory will sit between segments 0000 and 9000. Expansion ROMs were des […]
Show full quote

retrofanatic wrote:

Those sockets are certainly for some sort of ROMs but I am not sure for what exactly. If anyone can shed some light on this, it would be much appreciated.

If my calculations are correct, then 640kB conventional memory will sit between segments 0000 and 9000. Expansion ROMs were designed to sit above this, so that would put the start of this area at A000. Your board has six sockets, which could put them at A000, B000, C000, D000, E000 and F000. The last one has a chip in it, and since the BIOS normally sits at F000, this would appear to make sense.

So in theory if you got a 64kB ROM and stuck it in the first slot, its contents would appear at A000. Interesting!

I wonder whether you could flash DOS onto an EEPROM and put it in there so you could boot the machine entirely from ROM? It looks like you might only have D000 and E000 to play with as the other segments are used by the video card (except for CGA/MDA which doesn't use A000), so I guess it depends on whether you can fit everything DOS needs to boot into 128kB.

Thanks for the explanation Malvineous...it makes more sense to me now what ROMs could do for this system...I love that idea of somehow flashing an EEPROM with DOS! I would love that for this build. I haven't done any research on it, but now you have me thinking...

chinny22 wrote:

Man, retrofanatic you always do such a good job cleaning up your cases. I start off with good intentions but get to excited about getting he thing up and running.
I totally get wanting to keep your stack nice and tidy. part of me wants a nice clean line of similar cases with, part of me likes having different cases for different reasons, again I couldn't wait knowing I have a perfectly good system in storage just cause of the case.

Thanks! I try my best to at least clean everything and will do the "retrobright" thing once in a while.

A big part of being into this retro computing thing for me is that I at least try to clean and restore whatever I get to the best of my ability (without breaking the bank of course).

I hear you about having different cases too. I do have a bunch of other towers and odds and ends that I really enjoy tinkering with too but for my main retro gaming setup which will require having multiple systems using a KVM switch and other switchers in one area with limited space, stacking a few similar desktops or of relatively the same size on one another keeps everything neat and tidy and more manageable for me. I also like the fact that I can interchange parts between all the similar desktop cases I have.

keropi wrote:

Regarding the soundcard, there is no need IMHO to install both an AdLib and a SB... just install a 8bit SB and you'll have AdLib working too. I will be using a CT1320C with CMS chips with my XT.
Midi is a plus , you need an mpu in there! 😁

Scali wrote:

I don't think it's even possible, because they both have an OPL2-chip fixed at address 388h, so you'd get a conflict.

Thanks for the tip. I thought as much. I think I may just go with my adlib card and/or maybe my PAS 8bit card then and I do have a Roland MPU-IPC-T card for the MPU to drive all my external MIDI devices. Also, I remember having some strange 8 bit Adlib clone card that may be cool to try, I don't remember the make and model, but I will look for it and maybe give it a try in this XT machine.

keropi wrote:

Also totally agree on the CGA/EGA decision, vga is nice but we have a billion other systems that are vga-capable. I'll be sticking to the IBM CGA I got for my XT build.

Good point. That is exactly what I was thinking. I have enough systems with VGA, no need for it on this, being one of my oldest PC systems. I like the experience with an old XT to be as authentic as possible reletive to my experience with these old machines when I was younger (I never used an XT with VGA). Now that I have this XT, I am wanting to soon go bit older and find a nice Commodore PET system and fire up LOGO and some other primitive basic programs and games I used to play when I was in elementary school... 🤣..oh well I guess I will fire up my tandy stuff when I get the urge for some really old nostalgia fix. 🤣

EDIT:

Cloudschatze wrote:

In practice, having multiples of the same OPL type in a system doesn't really present much of a conflict. There's the duplication of FM sound from the similarly-addressed cards to deal with, which some folks seem to find desirable, but not much of a read component to be concerned with otherwise.

carlostex wrote:

AFAIK it is possible because the cards just "listen" to the address. So both cards will play at the same time. I'm not sure but it is a benefit of how the original AdLib was designed.

Sound Blasters do hog their other base addresses like 220h, so if another card is placed there it will conflict. Creative probably did this on purpose. OPL chips on Sound Blasters can be accessed from their base ports as well.

In light of this information, now I may reconsider and just at least try having both a SB and Adlib in there at the same time. I will be using a nice professional grade Sony mixer, so I could attenuate each cards output as I see fit so that will eliminate the problem of playing at the same time and any possible 'reverb' from having sound playing at the same time from two different sources (depending if I can get both to work properly in the first place).

retrofanatic wrote:

Thanks for the tip. I thought as much. I think I may just go with my adlib card and/or maybe my PAS 8bit card then and I do have a Roland MPU-IPC-T card for the MPU to drive all my external MIDI devices. Also, I remember having some strange 8 bit Adlib clone card that may be cool to try, I don't remember the make and model, but I will look for it and maybe give it a try in this XT machine.

You can use several cards with AdLib compatibility without any issues. Even the PAS was designed for 388h as base port in mind but in a way that it doesn't conflict with other cards and probably also not to undermine its own AdLib compatibility.

Now the original PAS in an XT is kind of a waste in my opinion. It is best suited in a 386/486. The greatest thing about the PAS is the dual OPL2, and the way it sounds when it is natively supported. I'm thinking of Fleet Defender or even Formula One Grand Prix. These games won't run in an XT.

I agree with Keropi a CT1320C or even a CT1350B is a good card for a Turbo XT. You'll have AdLib, Sound Blaster and CMS/Gameblaster. CT1320C's are better but harder to find than CT1350B's

Lovely attention to detail on this build 😀

Lovely build! I very like it. Nice to see that of good quality reincarnation of the real thing WOW very nice on cleaning.. I think that would cost you a lot sweat and tears..
Also i like it that there is another user with an JUKO ST clone computer.. Luckly iam not alone now.. I think you really got gold on that case, and that you was on time to get it before it was trashed.. NICE build..

retrofanatic wrote:

In light of this information, now I may reconsider and just at least try having both a SB and Adlib in there at the same time. I will be using a nice professional grade Sony mixer, so I could attenuate each cards output as I see fit so that will eliminate the problem of playing at the same time and any possible 'reverb' from having sound playing at the same time from two different sources (depending if I can get both to work properly in the first place).

There is little point to that though, since an SB is quite literally an Adlib with a DAC added to it. It uses the same original Yamaha OPL2 chip, so it will sound exactly the same (aside from possibly very minor differences in the output amplifier on the board).
So I don't quite see the point of having an Adlib next to an SB. Both cards may work in a single system, but the result would just be that both cards would be playing the exact same thing at the exact same time when you play an Adlib game, and the Adlib will be playing the FM music where the SB does both FM music and DAC sound effects when you play an SB game.

Scali wrote:

(aside from possibly very minor differences in the output amplifier on the board)

I find the Ad Lib MSC to be exceptionally noisy. Similar to the original, non-VCA MT-32 releases, there is an unmitigable amount of amplifier hiss in the output. This could be desirable as an authentic characteristic of any pre-SB FM playback though. Personally, I find it bothersome. In any event, installing an Ad Lib MSC alongside an SB would make doing A/B comparisons an easy thing, and I can think of worse ways to populate an otherwise empty slot. 😀

Well, I haven't done any comparisons, but early SBs are also very noisy. I can't really imagine an Adlib being more noisy than those SBs.
I literally went back to the store with my first SB, an SB Pro 2.0, because I thought there was something wrong with it.
My experience until then was with C64 and Amiga, which are both considerably less noisy. Given the fact that the SB Pro 2.0 actually cost exactly the same as what I paid for my whole Amiga, I was disgusted with the noise. Even more disgusted to find out that it actually was supposed to be like that. PC suxx.