VOGONS


First post, by iulianv

User metadata
Rank Member
Rank
Member

A few months ago I got a Tomato/Zida 4DPS board and tried to build a system around it (with an A80486DX4-120SV8B). I quickly noticed that the COM ports didn't seem to work, so I put the board aside and moved to testing other parts I had around...

Yesterday, while working on a 386 system, I noticed that there is one file in the CTMOUSE "distribution", namely COMTEST.COM, that can tell you what COM ports you have and what is connected to them.

I tried it on the 4DPS and it found two serial ports, with nothing attached to them no matter where I connected the mouse. So I thought that something broke between the I/O chip and the actual connectors on the board, but the weird thing is that, if I connect the small ribbon cable the wrong way, COMTEST.COM will show "modem" attached to the serial port, so something still goes through.

Is there any way to further debug this, or should I just toss the board and move on? There's also the option of using an ISA controller to get working COMs, but I usually don't like the idea of keeping parts that are not fully functional...

Reply 2 of 12, by iulianv

User metadata
Rank Member
Rank
Member

Damn, I never suspected a pin-out issue... but I'm glad I asked, just when I was about to strip the board of its goods (cache, jumpers, BIOS chip, battery holder) and throw it away. After some searching (found out there are two possible pin-outs for these cables), I took all the serial ribbons I could find, opened their DB9 connectors, selected one that didn't look like a non-working one, used a needle to draw a hole for the 10th pin (probably the reason I didn't use it in the first place), and successfully tested it with the serial mouse.

So, this short thread not only taught me something, but saved a perfectly good 486 PCI board from extinction - many thanks are therefore in order 😀.

Reply 3 of 12, by feipoa

User metadata
Rank l33t++
Rank
l33t++

Julianv, could you let me know exactly what pin on the 4DPS COM A port is supposed to go to which pin on the male end of the DB9 cable? The pins on the 4DPS are labeled 1-10, and labeled 1-9 on the DB9 cable. I am using mouse.com with test.exe to test the serial mouse, but have not had any luck in getting the serial mouse working.

The serial controller chip on this board is a Winbond W83768F. It is the same serial controller chip on a DTK PKM-0033S. I can easily get the serial mouse working on the DTK board. I checked the pin-outs on the DTK board's COM header vs. that of the DPS COM header - on both boards, the pins go to the same location on the serial controller chip (Winbond W83768F). From this, I know that the cable needed is 1-to-1, that is pin 1 on the header goes to pin 1 on the male DB9, pin 2 to pin 2, etc.

But for whatever reason, on 2 different 4DPS boards, I cannot get a serial mouse working with mouse.com/test.exe

Any ideas would be most appreciated.

EDIT:
This is what another forum goer found the pin assignments to be on version 1 of the board,

133MHz wrote:
[…]
Show full quote
IDC   DE9
1 1
2 6
3 2
4 7
5 3
6 8
7 4
8 9
9 5
10 x

From this post:
My first 5x86 build (also motherboard component level repair)

Julianv, what revision of the board are you using? Are these the pins you determined worked? I should reconfirm my "486 serial cable" is using these pins. I wonder if different board revisions used different pin assignments. I have two rev 2.1 boards.

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 4 of 12, by feipoa

User metadata
Rank l33t++
Rank
l33t++

I do not have any cable configurations like that posted in that other thread. Are there in fact 3 serial cable designations? The two cables I have are as follows,

IDC DB9
1 - 1
2 - 2
3 - 3
4 - 4
5 - 5
6 - 6
7 - 7
8 - 8
9 - 9

IDC DB9
1 - 1
2 - 3
3 - 5
4 - 7
5 - 9
6 - 2
7 - 4
8 - 6
9 - 8

Even if the IDC connector is placed on backwards, I do not get that other guy's pin configuration.

The IDC pins numbers are as shown next to the COM header on the 4DPS motherboard. The DB9 pin numbers are as printed on the male DB9 cable.

For those who have a working serial port on the 4DPS board, could you let me know your pin configurations, BIOS revision, and BIOS settings you are using? Thanks!

EDIT:

Interesting, this website lists the IDC pin numbers as follows,
http://pinouts.ru/SerialPorts/Serial9_pinout.shtml

1 2
3 4
5 6
7 8
9 10

whereas the 4DPS board lists the IDC pin numbers as,

1 6
2 7
3 8
4 9
5 10

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 5 of 12, by feipoa

User metadata
Rank l33t++
Rank
l33t++

I have confirmed that the 4DPS v2.1 uses this style cable,

IDC DB9
1 - 1
2 - 2
3 - 3
4 - 4
5 - 5
6 - 6
7 - 7
8 - 8
9 - 9,

whereby the IDC # corresponds to what is printed on the 4DPS' PCB. It so happens my serial controller on my 4DPS is dead. On another 4DPS, the floppy controller is dead. I received the boards like this. I figure since the 4DPS has a working PS/2 port, a serial port is of lesser importance than the floppy port. It may be that a lot of these boards from the Ukraine have been handled incorrectly at some point and get damaged due to static discharge.

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 6 of 12, by h-a-l-9000

User metadata
Rank DOSBox Author
Rank
DOSBox Author

The serial port usually consists of the "UART" ASIC and a level converter chip. If the latter is broken there is a chance to replace it as they are usually smaller chips.

1+1=10

Reply 7 of 12, by h-a-l-9000

User metadata
Rank DOSBox Author
Rank
DOSBox Author

Well, nope, on this mainboard it's an uncommon chip: W83768, it takes some skill and equipment to replace this kind of package if you actually find one to buy.
It also contains parts of the gameport.

One last thing to check is that your +12 and -12V lines to the mainboard are okay.

1+1=10

Reply 9 of 12, by feipoa

User metadata
Rank l33t++
Rank
l33t++

Yes, the multi-I/O card works fine, however the board looses its native value.

The hooked-up PSU voltages are:

+12V = 12.30V
-12V = -11.75V
+5V = 5.12V
-5V = -4.94V

The SMD package for the W83768F looks to have about 1 mm pin spacing. Has anyone had any luck using solder wick to remove these without cutting the leads off? If so, what about using a very sharp Weller tip, such as the ETU or ETS to contact solder such a chip back on? I have another board I can try this transplantation with, however I give it a low chance of success.

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 10 of 12, by rgart

User metadata
Rank Oldbie
Rank
Oldbie

I always thought com ports/pins configurations were standardized and universal across motherboards.

Until about a week ago when I got my hands on an EPOX EP-58MVP3C-M
Its a really nice board but I am missing the PS2, USB and COM Port headers/cables.

I tried all of the cables I had available for the com ports and nothing worked.

I noticed the same thing. When I plug the com port backwards into the motherboard ctmouse.exe would find a mouse but it obviously would not work.

the EP-58MVP3C-M uses a pin configuration like this:

1 6
2 7
3 8
4 9
5 10

Where do I find a cable like that?

Reply 11 of 12, by Panties

User metadata
Rank Member
Rank
Member
rgart wrote:
I always thought com ports/pins configurations were standardized and universal across motherboards. […]
Show full quote

I always thought com ports/pins configurations were standardized and universal across motherboards.

Until about a week ago when I got my hands on an EPOX EP-58MVP3C-M
Its a really nice board but I am missing the PS2, USB and COM Port headers/cables.

I tried all of the cables I had available for the com ports and nothing worked.

I noticed the same thing. When I plug the com port backwards into the motherboard ctmouse.exe would find a mouse but it obviously would not work.

the EP-58MVP3C-M uses a pin configuration like this:

1 6
2 7
3 8
4 9
5 10

Where do I find a cable like that?

Hi,

I'm not sure if you're still active in this forum... however.

I found this same board today and it was missing a COM port/cable, for my mouse.
However, I bought the COM port from ebay and refer to the manual below:-

Links:-
http://www.motherboard.cz/mb/epox/EP-58MVP3C-M.htm
http://www.elhvb.com/mobokive/Archive/Epox/ma … als/58mvp3c.pdf

Somehow, after cutting and rewiring.. and looking at the motherboard .pdf manual...etc... I got my mouse working.
1 Keyboard, 1 Serial Mouse, and i'm good to go. (I didn't bother about other ports, like printer...etc)

Hope this help!

Reply 12 of 12, by InjecTioN

User metadata
Rank Newbie
Rank
Newbie

For completion of information about this board, there’s a bug in the BIOS, which disables the floppy controller by default, while it’s set to enabled in the BIOS.

How to resolve that issue:
1. Disable floppy controller in the BIOS, save settings and reboot.
2. Enable floppy controller again, save settings and reboot.

It should work now.

The COM port issue is not being resolved by the same workaround, as I’m currently working on that same issue. I’ll have to dig more into the datasheet for that IC to get it to work I guess. The inputs and outputs on the datasheet are just numbered arbitrarily, so I’m thinking there has to be another way to connect or test this.

As you’ve mentioned, COMTEST.COM also shows a modem when connected with a wrong pinout (as do other IO-controllers), so that’s a good thing.

Next thing to try is to measure the traces on the motherboard. Maybe the rows on the IDC connector are swapped around on the motherboard layout? I’ll have to check.

Keeping you posted for more details.