Hi and welcome 😀

Nice old card. But probably not an EGA card. It looks a lot like an IBM MDA or Hercules clone, based on the same Motorola 6845 chip, or rather a clone in this case ("SY6845"). Being MDA/Hercules would explain why you're only getting mono output... there are a few STB 8b ISA cards in TH99 but nothing that maps onto this one.

What makes you think it would be EGA?

EGA was released at the end of 1984, but wouldn't become common until a year later. Generally EGA cards either had more controller chips than MDA/CGA/Hercules, or a smaller number of more integrated ones.

In any event it seems to be working correctly and would be a good match for an XT, so not all bad.

Hi and thanks for your reply,

I'm not too fussed that it is not a EGA Card as i only paid $5 For it from a swap meet and the guy i got it from was just clearing out his shed of old pc parts.

For a bit of fun i ran the Diagnostics Disk for the computer and it came out with this

Before it came to this screen, it asked if a monitor was attached to every Display adaptor which i thought it was strange as there is only one card in the computer. I Highly doubt it, but could the display adaptor have two modes? ie CGA and MDA? or is it a glitch on the Diagnostic Software.

No, that's very possible. Famous examples include the Tulip DGA board (with a nice external metal switch to switch between MDA/Hercules and CGA) and the ATi Small Wonder (as the name says, a very small card with dipswitches to select; it also has analog out making it an excellent all-round retro device).

But I don't think that's what's going on here - no board that I'm aware of does CGA and MDA at the same time, moreover your monochrome adapter apparently also has a printer port (common in the day), which your pic doesn't show, not even a header for it. So, I suspect that this board is CGA, not MDA (very possible as CGA uses the same Motorola 6845 chip), and those dipswitches are set for mono output. And you have another card in the system which offers MDA (+ possibly Hercules) and that printer port. MDA+CGA configs weren't exactly common, but the two cards could coexist and the combination was used for say showing Lotus 1-2-3 tables in mono on the one screen and graphs in glorious (low-res...) colour on the other.

Sounds like this was a pretty loaded system, math coprocessors also weren't common as they were expensive and few applications supported them. That supports the idea that it was a Lotus 1-2-3 or maybe AutoCAD workstation, as they would have used the co-pro and supported dual CGA/MDA display as well. The mind boggles how much a system like this would have cost back in the day...

could the display adaptor have two modes? ie CGA and MDA?

I was wondering about that as well. The pic is a bit fuzzy but it appears to have 16KB RAM, 22MHz crystal, two chips that could be ROMs, no composite video or printer port. Those are not the characteristics of either a CGA or MDA card. Maybe it is some kind of combo. The text in your pic certainly doesn't look like CGA resolution, but what if you attempt to switch to a CGA mode with MODE CO40?

I Would not know what this system was originally as i've been building it for the past few months. i'll put a build in the system specs area

Ok, first off here is a better photo's of the card.

i also ran checkit on the system and it came up this.

But thinking about what you both mentioned that it could be a MDA/CGA card and have 16k ram instead of the 4k it showed, i decided to flick all of the Dip switches on the card to on and it now shows this.

So it would appear that this card can either be in MDA (4k ram) mode OR CGA (16k ram) mode. (yes i changed the motherboard switches too)

Hello!

MB81416 = DRAM 16K*4 bit, which means that card has 64 KB, so most likely it supports Hercules graphics.
Try setting the switches to mono, and load MSHERC prior to running CHECKIT - then it should detect it as "Hercules" and run Hercules graphics tests.

However, while both MDA and Hercules use 16 MHz pixel clock, that card has a 22 MHz one - so it must do something more...
There were some "STB Chauffeur" cards supporting 132-column text and 1024x348 graphics - perhaps this is one of them?

dionb wrote:

no board that I'm aware of does CGA and MDA at the same time

I've got such a board - "AUTO MODE MONO/COLOR GRAPHICS PRINTER CARD", the manual also refers to it as "BI-014B" and "TM6310A".
It supports both Hercules and CGA, the primary video is selected via mobo's DIP switches (XT) or CMOS Setup (AT), later on one can toggle between primary and secondary with "MODE MONO"/"MODE CO40"/"MODE CO80".
The monitor must support both 15 and 18 kHz HSYNC - so don't try using it with an IBM 5151 !

Ok i've done a few more thing,

running the card in CGA 40 column mode crashes the system whenever it trys to run checkit
CGA 80 column runs fine (SW1 set to on,on,on,on,on,on,on,on)
MDA Mode runs fine (SW1 set to off, off, off, off, off, on, on, on,)

as i do not have MSHERC.COM, i cannot check or test to see if it has Hercules Mode

However, changing the position of jumper W7 makes the text appear smaller on the screen.

As i cannot find a manual or a part number for this card, i think this is about as far as i can go with it. i'll leave it in CGA 80 Column Mode for now

dunwood wrote:

as i do not have MSHERC.COM, i cannot check or test to see if it has Hercules Mode

MSHERC comes with MS-DOS 5.0, and probably some other DOS versions.

However, changing the position of jumper W7 makes the text appear smaller on the screen.

Narrower, perhaps? This would mean 132-column mode.

dunwood wrote:

[...]

as i do not have MSHERC.COM, i cannot check or test to see if it has Hercules Mode

Just run any game that supports Hercules and allows you to choose the video output manually and you find out soon enough 😉

Ultima 6 is a good example.

i'm limited to 720k games (No HDD at this stage) at the moment, so here's Leisure suit Larry in Hercules Mode (I think) the mode can be changed in game

and here it is in CGA

Had to cut the image down due to 2MB size

If you get any kind of bitmap image it's Hercules, as MDA really can only do characters. So you have Hercules there 😀