Part 2: The Power Supply

A Quick Test was running and i measured 5V and 12V, then the FI switch kicked in.

So i opened the PS and got a Surprise:

Glueing some FR4 under the Broken PCB with Epoxy:

Now it`s time to let everything dry 😁

Part 3: The Drives

5,25" Drives (still untested)

PCB repaired:

Epoxy and a quadratic FR4 piece make it as stable as new, drilled a new hole and now we ready to reattach it:

Caps for A-Matic Switching Power Supply:

looking forward to see the components for the build!
so far great job 😀

Part 4: Mainboard

Board installed 😀

A Unknown XT Board with Faraday Clone Chipset running the XT up to 9.54Mhz Speed.
I had real Fun finding a BIOS that works.

The Capacitors near PowerSupply are exchanged, there now 10uf Capacitors with 100nf X7R on the underside.

Turbo XT BIOS does only support 512Kb RAM on this Mainboard.
It does not enable the 128Kb Bank, sad..

So i sourced a BIOS from 1986! which works fine.
But is incombatible with VGA, it always shows Video Memory Bad if a VGA Card is inserted.

It also allows to Switch Speed with CTRL + Alt + "+", Default 4,77Mhz, 7,68Mhz and Turbo 9,54Mhz.
i would prefer booting at 9.54Mhz. But with this BIOS its not happen 😀

A Intel Above Board supplies another whopping 1,5Mbytes of EMS.

from time to time i find some 41256 so i filled 3 Banks of Memory in few months.

Part 5: Expansionscards

I have a CGA Clone Card, but no Screen.. that sucks a a bit, as my Monitor is HGC only.

The other Card is a Fullsize Zyxel Modem and fully Operating, i already tested it 😀

For now i have to use a 16BIT Multi I/O Controller as Floppy Controller and a XTIDE CF Card, as i have no Period Correct Controllers yet.

The Videocard i will use until i get a nice Colour CGA Screen 😉

reserved

Current State:

matze79 wrote on 2020-02-04, 19:41:

The Videocard i will use until i get a nice Colour CGA Screen 😉

Hey, what about using the CVBS (FBAS) output on a nice old TV set instead ?
The cheaper the TV set, the smoother/less-blocky the CGA graphics. 😉

Yeah only have a 42" TV and it looks very bad, the Picture Jumps up and Down 😀

I also got a ATI Graphics Solution but the MM12 Monitor is incombatible with it. Can get the Picture on Hold.
I set it to Mono Screen but it does not work properly.

with the cheapo HGC Card everything is fine.

This is my XT:

And IBM AT 286 6Mhz / 287 4Mhz:

Tested Drives today and found 2 working 5,25" 😀 i`m glad they work!.

matze79 wrote on 2020-02-06, 20:33:

Yeah only have a 42" TV and it looks very bad, the Picture Jumps up and Down 😀

Haha, I see. ^^ I've got the same issue anytime I use a CGA card.
Unlike MDA/Hercules, it doesn't use a proper 50Hz refresh rate, but is always de-tuned for some reason that's beyond me.. 😉
Anyway, using that V-Sync knob that you'll find on every video monitor really helps.

matze79 wrote on 2020-02-06, 20:33:

I also got a ATI Graphics Solution but the MM12 Monitor is incombatible with it. Can get the Picture on Hold.
I set it to Mono Screen but it does not work properly.

Hm. Sorry, I don't know what to recommend. Maybe the card is slightly off-frequency due to age, not sure.
Some Hercules had different crystals, so their frequency perhaps varried in the past also.
Or maybe it's the monitor that's a bit finicky here, not sure.

matze79 wrote on 2020-02-06, 20:33:

with the cheapo HGC Card everything is fine.

Hercules (aka Herkules or MGA - Monochrome Graphics Adapter) is awesome. It was very hi-res for its day and is on par with VGA in text-mode.
Speaking of VGA, some VGA cards even had an emulation mode of it. Because of this, I once thinkered with these little HGC compatible cards:
I thought myself "Why not the other way round, too ?" and experimented with a simple homebrew HGC-VGA adapter.
Unfortunately, it worked for me in text-mode only. Although it was supposed to not to (shoud work vice versa)..
See Hercules graphics on VGA monitors (mod)
By the way, if you're using a 286 CPU (maybe V20/30 or 80186, too ?) you can try out that C64 emulator.. It requires Hercules, too.
Re: "Childhood Embers" - 286 AT with Hercules graphics build

Edit: Not sure if you do know this, but CGA and Hercules can co-exist. Well, at least if only one screen page of Hercules is used (often the case).
That way, you can have a cool dual monitor setup! ^^ Simply enter MODE MONO for HGC and MODE CO80 or MODE CO40 for CGA (on DOS 5/6).

matze79 wrote on 2020-02-04, 18:56:

So i sourced a BIOS from 1986! which works fine.
But is incombatible with VGA, it always shows Video Memory Bad if a VGA Card is inserted.

Nice PC!

Does it boot with Hercules+VGA installed?

Yes, Hercules and VGA can coexist, i had this for long time in my PC until i moved to PCI only System.
Was useful for debugging and second Linux Console.

I got MFM Drives now.

But i need some tool to find all bad tracks to add them to the controllers defect managment list 😳
Spinrite woes, but disk boots fine.

Some testing:
Cloning C: to D:

https://www.youtube.com/watch?v=KsVa1xwzysA

80 Megs of rotating Steel ;D

matze79 wrote on 2020-03-30, 13:07:

Yes, Hercules and VGA can coexist, i had this for long time in my PC until i moved to PCI only System.

Do they coexist in this PC? You could try to boot with Hercules as primary adapter and init VGA from DOS after booting. Would be interested if this is possible. If the XT-BIOS prevents the VGA from being initialized this should work.

no the XT will execute Option ROM on VGA this will automaticly make HGC second.