I’ve encountered SVGA 9 pin on everything from IBM to HP and never understood what equipment these were meant for.

I have a strange 9pin to 15 pin adapter that works with them.

My guess is some sort of POS standard?

I've tried looking for cables. I want to make sure I get the correct cable. Also, I'm fine making my own cable if I know the 9-Pin to 15-Pin pin translation.

retroegde wrote on 2022-09-07, 00:40:

I've tried looking for cables. I want to make sure I get the correct cable. Also, I'm fine making my own cable if I know the 9-Pin to 15-Pin pin translation.

I’ve never seen adapter cables.

There is a formed 9pin to 15 pin monitor adapter, about 2.5” long

I would have to dig through my junkpile and see if it’s still there with markings

You used to be able to pick these up at any office store or radio shak mid 90’s

IBM used a 9-pin plug for analog video on their Professional Graphics Adapter. It has CYSNC on pin 4 and a mode pin on pin 5. There is a common variation of this pinout that has HSYNC on 4 and VSYNC on 5. 1,2,3 is R,G,B; 5,6,7 is the respective ground for R,G,B. 8 is digital ground. This pinout has also been used on analog/digital switchable multisync monitors by EIZO and NEC.

mkarcher wrote on 2022-09-07, 19:02:

IBM used a 9-pin plug for analog video on their Professional Graphics Adapter. It has CYSNC on pin 4 and a mode pin on pin 5. There is a common variation of this pinout that has HSYNC on 4 and VSYNC on 5. 1,2,3 is R,G,B; 5,6,7 is the respective ground for R,G,B. 8 is digital ground. This pinout has also been used on analog/digital switchable multisync monitors by EIZO and NEC.

Ah! So that's where the DE-9 analog video "standard" came from

I remember seeing adapters from DE-9 to DE-15 growing up and always wondering wtf the spec was for that or if it was even consistent

maxtherabbit wrote on 2022-09-07, 20:24:

I remember seeing adapters from DE-9 to DE-15 growing up and always wondering wtf the spec was for that or if it was even consistent

Hint: It's not consistent. There are multiple DE-9 analog pinouts. Another common one is to use R,G,B,H,V at the same position as CGA has them, but R,G,B as analog signals. In this case, chances are high that an IBM 9-pin analog monitor uses the IBM PGD pinout (or the separate sync variant of it).

mkarcher wrote on 2022-09-07, 21:00:

maxtherabbit wrote on 2022-09-07, 20:24:

I remember seeing adapters from DE-9 to DE-15 growing up and always wondering wtf the spec was for that or if it was even consistent

Hint: It's not consistent. There are multiple DE-9 analog pinouts. Another common one is to use R,G,B,H,V at the same position as CGA has them, but R,G,B as analog signals. In this case, chances are high that an IBM 9-pin analog monitor uses the IBM PGD pinout (or the separate sync variant of it).

TARGA was the most common, Sony, Magnavox and Amiga screens used it.

The primary difference was combined sync VRS separate sync, some screens could run off either

Well, I did some searching and found a cable on Amazon. "4.5 Feet DB 9 Pin Male to VGA 15 Pin Male Adapter Cable, RS232 to VGA Conversion Cable, YOUCHENG， for Computer,Printers, Scanners"

https://www.amazon.com/dp/B08GYKSJZT

It works! I just had to remove pin 9 from the adapter so it would fit in my PS/1 Consultant system.

retroegde wrote on 2022-09-09, 23:59:

Well, I did some searching and found a cable on Amazon. "4.5 Feet DB 9 Pin Male to VGA 15 Pin Male Adapter Cable, RS232 to VGA Conversion Cable, YOUCHENG， for Computer,Printers, Scanners"

https://www.amazon.com/dp/B08GYKSJZT

It works! I just had to remove pin 9 from the adapter so it would fit in my PS/1 Consultant system.

Thanks for reporting back. The title and text for that adapter is mostly bullshit (e.g. it is not related to RS232 at all, except for the plug to have 9 pins as does the compact version of RS232 ports typically used in (newer) IBM compatible computers), but as they describe the pinout, you nevertheless know what you are getting. If that cable works, it shows that my guess "the PGA variant with separate sync" seems to be correct. As a summary for later vistors of this thread:

The pinout of the IBM 59G9977 PS/1 SVGA monitor is like this:

11 - analog red
22 - analog green
33 - analog blue
44 - horizontal sync
55 - vertical sync
66 - red ground
77 - green ground
88 - blue ground
99 - digital ground

a professional cable would use 75-ohm coax for r/g/b and connect the respective outer conductors to pins 6,7,8; a cheap on just bridges 6-9 to a central shield used as ground.