VOGONS


Reply 21 of 31, by Skyscraper

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We are making a little bit of progress.

There is life in the board sort of, with certain memory configurations and the correspnding "correct" (and some incorrect) jumper setting for the memory amount the numlock key works... With (some) other jumper combinations the numlock key dosnt work.

The issue is that the numlock key is the only thing that works, no video and the board wont flash the light on a floppy drive connected to an 8bit GW-202 controller. Still numlock working with some memory configurations and not with others and working with the some jumper settings but not others at least indicate there is some life in the board.

These memory configs "work" with the "correct" jumper setting for the memory amount. All these settings "work" both with and without parity chips installed.

Memory chip

M
M
M
M

256KB

Dip switches 3 and 4 set to Off Off or Off On (both can be 256KB following Jukos switch scheme)

M X X X
M X X X
M X X X
M X X X

M X X X
M X X X
M X X X
M X X X

512KB

Memory dip switches set to Off Off (not listed for the bord Im using as reference so I used the settings for 1MB which "worked")

M M X X
M M X X
M M X X
M M X X

M M X X
M M X X
M M X X
M M X X

I also tried this setting with the 4x 4464 present in the dip 19 sockets and jumpered for 640KB (with and without parity chips).

The opposite "works" aswell, at least with 4x 4464 in the dip-19 socklets and jumpered for 640KB memory (on off).

This does strangely enough "work" jumpered for 640KB, I only tried it with the 4 4464 chips present.

X X X X
X X X X
X X X X
X X X X

M M M M
M M M M
M M M M
M M M M

and also the opposite

And finally 1 MB

M M M M
M M M M
M M M M
M M M M

M M M M
M M M M
M M M M
M M M M

Placing the memory like this results in a non working numlock key.

M X M X
M X M X
M X M X
M X M X

M X M X
M X M X
M X M X
M X M X

And the same is true with the opposite. With and without the extra 128KB and with and without parity chips.

Obviously with some of these configs some memory would be missing as the banks can not be both ways, which is correct is impossible to tell without any output.

Knowing for sure where the PC speaker should go would probably be beneficial but I dont think the board even gets as far as counting memory.

As the board should still work with my 8 bit I/O card even without any video card at all it's probably not as easy as the board not accepting VGA cards (what ever jumper settings).

With most these settings I have tried all combinations for the two memory amount dip switches and the parity dip switch in both positions. I have kept the video dip switches at on + on for no video (or EGA/VGA) most of the time.

Carlostex hypothesis that the issue is memory incompatibility with 44256 chips seems more and more likely?

Last edited by Skyscraper on 2016-05-01, 13:04. Edited 2 times in total.

New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.

Reply 22 of 31, by Robin4

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carlostex wrote:
Skyscraper wrote:

If this ends up beeing memory incompatibilty with 44256 chips I will be somewhat irritated but I can't just make my self buying the expensive DIP-19 "MB81C1000-10 1Mx1bit DRAM" chips I have been suggested could work with this board as I have loads of 44256 chips and this is what most late XT clone boards use. I rather buy a "Lo-Tech 1MB RAM board" as I could use that in my other XT systems which only have 640KB to get some UMB space if this board should end up beeing unsalvageable.

It's pretty disappointing when things don't work. I too was a bit baffled when my Juko board didn't work with 44256 DRAM. The 1MB RAM card from lo-tech is indeed a solution and maybe you can save some bucks if you build it yourself. Still with the cost of PCB + parts + shipping to Sweden i'm not sure it will be cheaper than the outrageously expensive old 1MB x 1 DRAM chips. It is also a card that requires much harder work/effort due to those annoying SMD resistor networks. However it's a card that can provide not only 640KB memory but also upper memory blocks. So although more expensive its a much better investment overall, and can always be used in other systems as well.

I will be looking into getting one of these Juko Nest boards too, but i want the 8086 version which Anonymous Coward/Robin4 own.

Dont forget that those Juko boards will also have UMB memory too.. They can maxed out to 1024MB of memory.

~ At least it can do black and white~

Reply 23 of 31, by Skyscraper

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Robin4 wrote:
carlostex wrote:
Skyscraper wrote:

If this ends up beeing memory incompatibilty with 44256 chips I will be somewhat irritated but I can't just make my self buying the expensive DIP-19 "MB81C1000-10 1Mx1bit DRAM" chips I have been suggested could work with this board as I have loads of 44256 chips and this is what most late XT clone boards use. I rather buy a "Lo-Tech 1MB RAM board" as I could use that in my other XT systems which only have 640KB to get some UMB space if this board should end up beeing unsalvageable.

It's pretty disappointing when things don't work. I too was a bit baffled when my Juko board didn't work with 44256 DRAM. The 1MB RAM card from lo-tech is indeed a solution and maybe you can save some bucks if you build it yourself. Still with the cost of PCB + parts + shipping to Sweden i'm not sure it will be cheaper than the outrageously expensive old 1MB x 1 DRAM chips. It is also a card that requires much harder work/effort due to those annoying SMD resistor networks. However it's a card that can provide not only 640KB memory but also upper memory blocks. So although more expensive its a much better investment overall, and can always be used in other systems as well.

I will be looking into getting one of these Juko Nest boards too, but i want the 8086 version which Anonymous Coward/Robin4 own.

Dont forget that those Juko boards will also have UMB memory too.. They can maxed out to 1024MB of memory.

My two "10 MHz Turbo XT" motherboards maxes out at 640KB so I could have use for the Lo Tech memory card to get UMBs for one of those if it won't revive my Juko board. It's low priority though, right now I want to put this stupid motherboard in a box and pretend it dosnt exist over the summer. I will probably try again to get it working come winter.

New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.

Reply 24 of 31, by Robin4

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Maybe you could try another bios with support for 1024KB of memory. Perhaps it will accept all the memory then.

~ At least it can do black and white~

Reply 25 of 31, by Skyscraper

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Robin4 wrote:

Maybe you could try another bios with support for 1024KB of memory. Perhaps it will accept all the memory then.

My two "10 MHz Turbo XT" boards only have 4x DIP-20 sockets for 4x 44256 chips + 4x DIP-19 sockets for 4x 4464 chips so 640KB is all they will take without using a memory card. These boards dont even have sockets for parity. BIOS wise they work perfectly with the BIOS from the Juko Nest board but the performance was exactly the same as with the stock BIOS.

1MB memory support is the main reason it would be nice to get the Juko Nest board going.

New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.

Reply 26 of 31, by h-a-l-9000

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You can still go this route: http://www.minuszerodegrees.net/supersoft_lan … dmark%20ROM.htm
Even without the CGA/MDA card it will give beep codes. It might be possible to flash it into your XTIDE eeprom and putting that in the BIOS socket.

To figure out the connectors for speaker, reset etc.: Please don't measure voltages, but continuity instead (with power off). First, check which of the pins have zero resistance to 5V and GND. Maybe make a sketch as I did with the memory bank. Then check if there is one pin which has continuity to the collector of the transistor (most likely center pin) with only 30 or similar ohms.
The remaining headers should be keylock, power LED, turbo SW, turbo LED, reset. You can find reset by bridging each header with a ~330 ohms resistor. When you find it the reset LED on the POST card will turn on. The power LED should have a resistor to 5V (maybe GND) at around 150 ohms. The turbo LED should have a resistor of several hundred ohms to 5V or GND. Turbo LED should turn on or off when you bridge the turbo switch header.

1+1=10

Reply 27 of 31, by Skyscraper

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h-a-l-9000 wrote:
You can still go this route: http://www.minuszerodegrees.net/supersoft_lan … dmark%20ROM.htm Even without the CGA/MDA card it wi […]
Show full quote

You can still go this route: http://www.minuszerodegrees.net/supersoft_lan … dmark%20ROM.htm
Even without the CGA/MDA card it will give beep codes. It might be possible to flash it into your XTIDE eeprom and putting that in the BIOS socket.

To figure out the connectors for speaker, reset etc.: Please don't measure voltages, but continuity instead (with power off). First, check which of the pins have zero resistance to 5V and GND. Maybe make a sketch as I did with the memory bank. Then check if there is one pin which has continuity to the collector of the transistor (most likely center pin) with only 30 or similar ohms.
The remaining headers should be keylock, power LED, turbo SW, turbo LED, reset. You can find reset by bridging each header with a ~330 ohms resistor. When you find it the reset LED on the POST card will turn on. The power LED should have a resistor to 5V (maybe GND) at around 150 ohms. The turbo LED should have a resistor of several hundred ohms to 5V or GND. Turbo LED should turn on or off when you bridge the turbo switch header.

There, more less less done with mapping out the headers at least.

GND marks continuity agianst GND (measured at B1)
No pin had zero resistace against +5V but one pin on J5 has very low resistance to +5V (measured at B3)

From the left (on the picture on the first page), all voltages when turned on measuered against GND (B1)

J6 [GND and 338 ohm against +5V -- X] ---> When turned on X is 5V, Turbo led

Unnamed header [555 ohm to +5V, 895 ohm to GND -- GND and 338 ohm to +5V] ---> When turned on pin 1 is +5V, Power led

J5 [47.5 ohm to 5V, 386 ohm agianst GND -- Y] ---> Y has zero (0.5) resistance against the outer pin on the transistor that isn't GND but no continuity (1534 ohm) to the middle leg ---> Pin1 is 5V when turned on pin2 ~1V but varies a little, PC speaker?

J5 seems a bit strange for a speaker? but I guess it will only measure as one would think when beeping? No beeping with a speaker on this header when I did a quick test, but no ill effects either (everything measures as before once the speaker is removed). Something odd is going on in any case as adding the spaker makes the board stop responding to numlock.

J4 [300 ohm to +5V -- GND] ---> When turned on pin is +5V. Reset.

J3 [X-- Y] ---> X is 5V when turned on and Y is 0V but no continuity to ground when turned off. Turbo switch

J2 [556 ohm to +5V -- Y] ---> These pins are both +5V when the system is turned on. Keylock?

Just to make sure I tested the spaker on J2 as this is the only other semi unknown header and I do not really dare to short these pins as both are +5V against GND, (who knows the magic smoke might escape) but the speaker should be "safer" than a short. No beeps but numlock kept working. It would be very strange if this is the PC speaker header as it has no connection to the transistor at all so my bet is that this is keylock even though I think it measures very strange for a switch. Again there were no ill effects, this header still measures +5V against GND on both pins.

I will look into diagnostic ROMs in the future once I have bought an eeprom programmer and some empty ROM chips. I'm not going to mess with the XT-IDE ROM chip, leave working stuff be is my motto! 😀

Last edited by Skyscraper on 2016-05-02, 00:55. Edited 3 times in total.

New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.

Reply 28 of 31, by Skyscraper

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Bump as it took some time and some food to get done so I have edited the post above more than a little.

I think this is as far as I will get for now.

New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.

Reply 30 of 31, by Skyscraper

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h-a-l-9000 wrote:

Speaker should not influence anything - maybe J5 is really keylock...
Did the bent ISA slot cause damage, such as pads lifted and traces ripped out?

Yea, J5 could be keyloack even if that would be somewhat strange...

No I dont think the bent ISA slot damaged the board. After these pictures were taken I fixed it and now you can't see it was ever bent.

The board has some small scratches which don't look deep enough to matter but if it isn't a memory issue there must a broken component/IC or a shorted/cut trace somewhere.

New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.

Reply 31 of 31, by carlostex

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Robin4 wrote:

Dont forget that those Juko boards will also have UMB memory too.. They can maxed out to 1024MB of memory.

Have you managed to get UMB's from a Juko board when configured to 1024KB? Which driver did you use?