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I found an old Samsung CRT color monitor. I was hoping to use it for playing retro DOS games, but the main issue that I'm facing is that it's using RS-232, which as far as I can tell, is a very unusual choice for a monitor. I'm fairly confident it is actually RS-232 and not VGA. It has 9 pins: Five on top, four on bottom, female port.

Here is a photo of the port:
enter image description here

The best I found is an adapter that coverts RS-232 to USB, but the Amazon page says explicitly that it's not for monitor use and as such I'm hesitant to make the purchase.

If anyone can give me suggestions on how to best adapt this monitor to a more modern format, please let me know. I'd prefer DisplayPort, but I can work with HDMI or even A/V.

Display Information:

  • Brand: Samsung
  • Model: CVP4237P
  • Manufactured: May 1995, Color Display Monitor
  • FCC ID: A3LCVK423
  • Serial: H2JF502053
Giacomo1968
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link jones
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4 Answers4

28

If you are interested in playing retro DOS games, then I would suggest investigating DOSBox. This should work with your current monitor.

The original IBM PC and clones did not use monitors that communicated through serial RS-232. Instead, RS-232 was primarily used for communication with modems and printers. The original IBM PC offered CGA graphics, which was output using a female DE-9 connector as outlined below.

DE-9

The pinout is given below.

CGA pinout

In a deleted comment, user Hearth pointed out that "EGA and Hercules graphics also used the same 9-pin connector." The EGA pinout can be found here and the Hercules pinout (which is the same as MDA) can be found here. User plugwash posted an answer which includes the Professional Graphics Controller (PGC) manufactured by IBM for PCs This is often referred to as the Professional Graphics Adapter (PGA), which also used the same 9-pin connector. The PGA pinout can be found here.

The monitor given in the question has a female 9 pin VGA connector. The pinout is given below.

9 pin vga

This is not CGA, EGA, PGA or MDA (Hercules) compatible.

The latest VGA uses a DE-15 connector as outlined below.

DE-15

The relationship between 9-pin and 15-pin VGA pinout is given below.

9 to 15 pinout

Connecting monitor in the question to a DisplayPort could be accomplished by the use of the following.

A cheaper alternative would be the following. However, this would leave a lot of hardware attached directly to the back of the monitor.

Note that modern computers expect to digitally read the VGA monitors capabilities direct from the monitor over the connecting cables and adapters. This may not be possible with your monitor. So, beware than even if the cable and adapters can deliver the video signal, the computer may not emit a signal without first knowing the monitors capabilities.

References

Giacomo1968
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David Anderson
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19

Based on your description, the display seems to be a SyncMaster 3Ne (CVP4237P).

This link on Reddit is for the Samsung Syncmaster 4NE but it seems to have a similar 9 pin connector.

While you say you want a DisplayPort or HDMI connection, the are both digital connections and VGA is analog. So your best bet is a VGA cable like this one found on eBay:

enter image description here

Giacomo1968
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14

Your guess about RS-232 is simply wrong.

According to service manual schematics the monitor has an analog VGA compatible input, but with a DE-9 connector instead of the more standard DE-15 connector.

You simply need to build a custom cable or adapter to connect it to any standard VGA output, be it on your motherboard, video card, or using some kind of adapter.

The monitor will of course be missing Extended Display Identification Data (EDID) and other ID features so you might need to force the video card drivers to output a format that the monitor supports, because it can't be auto-detected. You might as well build an EDID memory chip to your VGA adapter.

David Anderson
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Justme
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7

I'm fairly confident it is actually RS-232 and not VGA.

If your only experience with technology is modern consumer tech, then it's easy to get the impression that there is a 1:1 correlation between connectors and the interfaces those connectors carry.

That is not how things worked historically, and it's still not how things work when you expand your horizons beyond consumer technology into the industrial and scientific world. Historically connectors were made by connector manufacturers and then adopted by equipment manufacturers.

The same connector would often be used for multiple incompatible applications, sometimes even on the same system. The IBM PC and compatibles were especially susceptible to this as the design of the PC expansion slot backplate ruled-out many common connectors and often left little room for labelling.

Unfortunately, even people who should damn-well know better get this wrong, as can be seen from the various product listings given in other answers. A VGA to RS-232 cable makes no sense as a concept, most likely the product sold as such is actually a mislabelled monitor cable but it doesn't exactly inspire confidence in the seller.

In terms of the 9 way D connector this was used for a number of applications on the IBM PC family of computers.

  • The EGA/CGA/MDA video interfaces with "digital"* colour signals. The pinouts for all of these were quite similar, with the sync signals and the grounds in the same place and an EGA card could be configured to support a CGA or MDA monitor.
  • Serial ports, starting with the paralell/serial combo card for the PC/AT.
  • IBMs professional graphics controller (sometimes referred to as PGA) used a 9 way D connector for analog RGB video. The pinout was completely different from MDA/CGA/EGA.

At the "PC end" of the cable, connector gender was used to distinguish between video ports and serial ports, but since cables could be either male to male or male to female this is of limited help for the peripheral end of the cable. It also does not distinguish between a MDA/CGA/EGA like port and a PGA like port.

In 1985, NEC introduced their JC-1401P3A "multisync" monitor. This had a 9 pin input with a 10 pole mode switch to select between analog and digital mode. In TTL mode it used a CGA/EGA compatible pinout, while in Analog mode it used a PGA compatible pinout but in addition to the composite sync used by PGA it also supported separate horizontal and vertical sync signals.

VGA came along in 1987 and chose to use a 15 pin high-density connector for the video output. This became the de-facto standard for analogue video outputs on PCs, and was also adopted by some non-PC computers.

The monitor end though was less standardised. Some monitors used 15 pin connectors, some used 9 pin connectors, some used captive cables.

The variant of the PGA pinout with seperate horizontal and vertical sync signals seems to have retroactively become known as "9 pin VGA", though VGA did not exist when it first appeared.

PIN MDA CGA EGA PGA 9 pin VGA
1 Ground Ground Ground Red Red
2 Ground Ground Secondary Red Green Green
3 Red Primary red Blue Blue
4 Green Primary green Csync Hsync
5 Blue Primary blue Mode Vsync
6 Intensity Intensity Secondary green Red Ground Red Ground
7 Video Secondary blue Green Ground Green Ground
8 Hsync Hsync Hsync Blue Ground Blue Ground
9 Vsync Vsync Vsync Ground Ground

I can't seem to find a manual for your specific monitor, but I did find a link to a manual for a different samsung monitor which follows the "9 pin VGA" pinout listed above. I strongly suspect this is what your monitor is using, it may also support combined sync, many monitors did.

References:

* In the sense that each line was either high or low, not in the modern sense of a digital data stream.

plugwash
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