X post re: IBM 5150 video question circa 1981

[~A_Sammy]

Hi,
I got the following email tonight from a buddy:
(1981)--that I'm going to sell since it's collectible. Well, I finally got
around to looking at it, and it powers up, but its video port won't work
with current monitor plugs. Since the ports aren't labeled, I'm guessing
that the video port is the one that's shaped and sized like the current
ones. This has 9 pinholes, 5 on one row, 4 on the other. Current monitor
plugs seem to have 3 rows of pins. Do you have a monitor that could work?<<

It sounds to me that he is describing a serial port, but a 1981 IBM is way
before my time.

Can anybody tell me what the score is on video for an old box like that?

Thanks,

Sammy

 

[Glenn Mathis]

Hi,
I got the following email tonight from a buddy:

(1981)--that I'm going to sell since it's collectible. Well, I finally got
around to looking at it, and it powers up, but its video port won't work
with current monitor plugs. Since the ports aren't labeled, I'm guessing
that the video port is the one that's shaped and sized like the current
ones. This has 9 pinholes, 5 on one row, 4 on the other. Current monitor
plugs seem to have 3 rows of pins. Do you have a monitor that could work?<<

It sounds to me that he is describing a serial port, but a 1981 IBM is way
before my time.

Can anybody tell me what the score is on video for an old box like that?

Thanks,

Sammy

I still have my old system and can confirm that the display connector
was a nine pin connector. I still have the old documentation and it is
all software related. I will also note (for my AMDEK 310A monochrome
monitor) only six pins were used. Right side (5 pins on top) 1 and 2
only and the 4 bottom row pins (I.e. 3, 4 and 5 not connected). I may
still have better info around (or power up the old system and make some
measurements) but it would be hard to blow off all the dust.
Glenn

 

[~A_Sammy]

Thanks for the quick reply, Glenn.

Looks like it has to have a monitor that was made for it if I'm reading you
right.

Sammy

 

[JAD]

VGA Vs SVGA 8bit Vs. 16 bit the connectors on 8088 era machines were 4 color or Hercules monochrome. The VGA outs were
different. There were some vid cards were made that gave 16 colors (PS2).

 

[Michael Black]

I still have my old system and can confirm that the display connector
was a nine pin connector. I still have the old documentation and it is
all software related. I will also note (for my AMDEK 310A monochrome
monitor) only six pins were used. Right side (5 pins on top) 1 and 2
only and the 4 bottom row pins (I.e. 3, 4 and 5 not connected). I may
still have better info around (or power up the old system and make some
measurements) but it would be hard to blow off all the dust.
Glenn

Of course, there were two standards for the time. If you wanted text,
you'd get the IBM monochrome board, wait that was referred to as an MDA
board, and a monitor to go with it. If you were more interested in color,
you'd get an IBM CGA board, and a monitor to go with it. The first arrived
with the IBM "PC" in 1981, while the latter cane along in 1982.
Both used a female 9pin "DB" connector, though of course the pinouts
were not the same, and neither board used the same monitor.

I know later CGA boards had a header to add a phono connector for
composite out (I've even seen some with the phono connector right on
the board), and this can feed the composite input of a TV or standard
monitor (ie the sort of thing one can connect the phono connector output
of their VCR or DVD player to). Or, one would connect this point to
their tv set via an RF modulator.

Given an NTSC monitor (ie a TV set), the CGA board is useable without
tracking down a fancy monitor. The MDA board used a higher horizontal
frequency, though not as high as VGA, and one is far less likely ti
stumble on one of those monitors.

(And of course, if you wanted both, you'd go after the third party Hercules
board.)

The next video level, EGA, also used a 9pin "DB" connector. Surely
there is nothing to guarantee that the video board is the original.

Michael

 

[~A_Sammy]

Thanks for all the replys and explainations. This question turned into a
good history lesson for me on computer video.
Sammy

 

[Walt]

Yes, the 5150 monochrome display had a "different" interface than
anything else. It only worked with the Monochrome Display and
Printer Adapter (MDPA).

You can also tell the difference between the MDPA and the CGA cards,
when installed, by the printer port on the MDPA card back bracket.