heh yeah, this is fixed now 😁
...needs more roland though 🤣 🤣 🤣

Looks great! My only TV that can handle NTSC composite is an LCD 🙁

Epic build! I need to find a good desktop case for my XT build. I'm itching to start building mine!

thanks guys 😀

@bjt
I found that the later crt models do support ntsc color encoding, it's just a matter of finding one of these later models...

Today is very easy to find the NECV20 HL, which is a lower power version and that can clock at 16MHz. It would be extremely cool to have a drop in socket circuit with its own clock crystals that would help clock the CPU at 16MHz. A NEC V20 running independently at 16MHz while keeping the system bus at 10MHz would provide for a very nice speed boost which could replace a low clocked 286. I suspect it could be faster than the original IBM AT.

edit: Hmm Sergey's XT runs a NEC V20HL at 13.3MHz and is almost as fast as a Model 30-286 IBM PS/2.

Great machine keropi, have fun with it! Have one too, though it is without the plastic faceplate and has a badly corroded motherboard due to battery acid. It's still around for parts (5.25" floppy drives, ISA cards), though if I don't manage to restore another XT-clone (the Acer 500+), I'll have a go at repairing the bad traces on its motherboard.

keropi wrote:

Did the V20 upgrade today , the system does feel snappier. The benchmarks don't show a huge difference but even simple stuff like dir command calculating free space is faster.
Most importantly some stuff that could not run before now work - don't think big 🤣 think something like EDIT.COM from DOS7x : with the 8088 the pc froze , now it runs fine 😀
I did lost the 1:1 4.77mhz speed though, with the V20 at low-speed 8088MPH now complains that there is a +16% speed difference. With the 8088 there was no such complain.

Well, 8088MPH depends (at least for some parts) on cycle-exact timing, not even all XTs with a 4.77MHz 8088 will work. So obviously if a CPU runs faster at the same clock it won't work. Also, doesn't the demo depend on some instruction(s) a NEC CPU doesn't implement? (SALC?)

Now what would be totally cool would be an interposed socket to be able to switch between 8088 and V20. (Not on the fly of course, but having to reboot wouldn't be too bad.) I don't know if anyone has ever tried that.

keropi wrote on 2015-10-16, 17:23:

Keyboard update: turbo+F_keys does change the repeat rate of keystrokes 🤣
here are some pics with the XT/AT switch fitted , a very simple job:

You had only added that switch on the back?

Robin4 wrote on 2020-12-25, 06:07:

You had only added that switch on the back?

yes

Robin4 wrote on 2020-12-25, 06:07:

keropi wrote on 2015-10-16, 17:23:

Keyboard update: turbo+F_keys does change the repeat rate of keystrokes 🤣
here are some pics with the XT/AT switch fitted , a very simple job:

You had only added that switch on the back?

That is the way they were back then... The 1987 enhanced keyboard on my Redstone Computers XT Turbo is exactly same.

No components (missing) where added?

Robin4 wrote on 2020-12-25, 09:24:

No components (missing) where added?

yes just the switch
enough with the xmas trolling 🤣

Amazing work on that.

I've heard these systems get very good MPG.

keropi wrote on 2020-12-25, 09:30:

Robin4 wrote on 2020-12-25, 09:24:

No components (missing) where added?

yes just the switch
enough with the xmas trolling 🤣

Strange why it wasnt added by the manufacturer at the first place? Because that switch wouldnt be that expensive if the XT / AT Circuit is already there.
No it wasnt a troll, but a question which things you had to added to make it work.