Help with CGA/Hercules card (Yamaha chipset)

[Rauli]

Last week I acquired an 8-bit ISA card expecting to be an EGA, but after closer examination it turned out to be a CGA/MDA/Hercules, or that's what it seems to be.





I can't identify it. This should be no problem for this kind of card (usually they don't need drivers), the problem is that I'm not able to make it work on Hercules mode, and what I like most on retro hardware are Hercules graphics in a green-phosphor screen!

It has a 6 switches block, and I have tried all combinations (I think) in both an orange-phosphor EGA (CGA compatible, in theory) and a green-phosphor MDA/Hercules screen.

There are two switch combinations with readable output on the EGA screen, with 16-gray (I mean: orange) levels, so I understand that the card was working in CGA mode (while in those combinations sysinfo programs detected a CGA and an MDA at the same time).

Ahd there is one switch combination with readable output on the MDA/Hercules screen, the problem is that sysinfo programs detect a plain MDA, no trace of Hercules (and I have verified that at least some of those programs report "Hercules", not "MDA", on other Hercules compatible cards).

Althought the card is not identified, I have some information about all the chips it has:

• The biggest one is an 8748 microcontroller with EPROM, manufactured by NEC and with a Texas Instruments sticker (having a TI logo seems strange to me). The datasheet is available, but not very useful, not knowing its connection to the rest of the card, or the EPROM contents.
• The next (in size order) is a SiS 23C07 character generator with ROM, storing characters definition. It seems the newest chip in the card, manufactured in mid-1988. A very short list of features is available, too.
• The square one is a Yamaha V6366B-F, I can't find the datasheet for this chip, but I have found it for the Yamaha V6366, which should be the "family fahter", with the "B-F" being a version with added or removed features. According to the datasheet, the V6366 includes all fatures of the MC6845 and supports all CGA, MDA and Hercules modes. And on page 8 there are two configurations to be used as CGA (2 chips of 8K x 8 bit) and as Hercules (2 chips of 64K x 4 bit).
• Finally, the rest of chips belong to the 74LS series, except the 2 darker chips on the left, which are TMM41464AP-12, the datasheet is also available and they are 2 chips of 64K x 4 bits... so the card comes with Hercules memory.

Does anybody have any information about this card, or a similar one? (I have seen photos of other CGA/Hercules cards with Yamaha V6366-something chips) Or any idea about how to activate the Hercules mode?

There's no FCC-ID, and the only identification in the card is LD-200S, being the 2nd zero slightly bigger and rounder than the 1st, so maybe it's an "o" instead: LD-20OS

No clue about the maker, except the Texas Instruments logo on the sticker, could it be a TI card?

And the most important thing: How to make it work as an Hercules card?

 

[Chuck(G)]

That 8748 really has no place on a display-only card. I'm wondering what the function of the 20 pin header at the top-left of the card is meant for. I wonder if this might belong to a POS terminal with an interface to a hand scanner or some such specialized thing.

 

[FishFinger]

According to this page:

http://ryan.tliquest.net/pictures/Old Stuff/LD-200S/

This card was part of some portable 286 computer, probably a Scantech LCD-286
(the LCD screen has a custom power supply with a Scantech Computer Systems sticker)
The only identification on the card is the "LD-200S" silkscreen, and is an 8-bit ISA
LCD controller card that drives a Toshiba TLX-1181-G3B1 640x400 monochrome LCD screen.

So the 20-pin header is most likely for the LCD. And the switches may well set options to do with the LCD as well as the DE-9 output.

 

[Rauli]

OK, thanks!

The Yamaha datasheet mentions flat panels, LCD and plasma screens, so I expected a non conventional application (not home or office PC), but it also mentions compatibility with CGA, MDA and Hercules. In fact I made it work as CGA and MDA... but not as Hercules. In MDA mode I counted pixels of semi-graphic characters and they have the full 9x14 pixel definition, so it is real MDA.

If the card in the previous link is set for the LCD screen, the switches in ON position are 1 and 3, which is not one of the settings which worked for me:
For EGA screen (CGA mode): Switch 2 ON, or switches 2 and 3 ON. With these 2 settings, switch 5 made the character lines thinner if ON.
For Hercules screen (MDA mode): Switches 4 and 5 ON.

Any other combination (including the settings in the photo of previous link) didn't produce any readable output on any of my screens.

There were other few combinations which produced text on my Hercules screen, but with a fast continuous vertical scroll (like vertical synchronization out of range).

Others made visible only the upper half of characters. And others made appear the upper half in the bottom part and the bottom part in the upper part of any character cell. For example, instead of "X" you could see the "^" part on top of the "v" part. Strange, uh?

 

[Chuck(G)]

Have you tried setting MDA mode and then twiddling the registers yourself to see if you can force Hercules mode?

 

[Rauli]

Have you tried setting MDA mode and then twiddling the registers yourself to see if you can force Hercules mode?

Mmm... no, I don't know how to do it. And the datasheet focuses on pins and different chip packagings, but doesn't have a single line about registers.

 

[Rauli]

Mmm... no, I don't know how to do it.

...but I let some programs do it for me.

I have tested some games which supposedly support the Hercules card, with the following results:

Games which auto-detect the graphics card, don't work, as they detect MDA (just like MSD and other sysinfo programs).
Games which can be forced to use Hercules graphics (via parameters or because they ask)... display Hercules mode graphics!

For example:
Karateka: Doesn't work. "Requires a graphics card to run properly". I have seen it on a list of games supporting Hercules mode, but I'm not sure my executable does (some games had different executables for different graphics cards).
Starwars: It works without any issue. You can specify the card via parameter ("starwars cga" or "starwars herc"). I supposed it would "activate" my Hercules card but after playing I run again MSD and it still detected "MDA".
Poogaboo: At start it displays a text-mode menu to select the graphics card. So I selected Hercules and it works, but the screen scrolls up continuously, like vertical sync out of range. I turned one of the screen back knobs and could stop the scrolling, but I get a double screen. I can see the game small in the upper half and again in the lower half.

Is like the two games used different Hercules modes, with vertical sync incompatible with my screen for one of those modes. But there's only one Hercules graphics mode, isn't it? So I don't understand this behaviour.

 

[Chuck(G)]

I wonder if the other mode might be for something like Plantronics mode. ISTR that the AT&T 6300 uses different monitor frequencies as well.

 

[Rauli]

Mmm... I don't think so, the Plantronics was a kind of "SuperCGA" (memory buffer organized like CGA but more colours or resolution), not an extension to monochrome cards.

Fortunately, last I acquired an ATI Small Wonder Graphics Solution Version 2 which is also a CGA/Hercules, and when configured as Hercules, it is detected as an Hercules by all programs.

But as it seems that there must be always a problem, it should be configurable as a "full" Hercules (2 graphics pages, 64 Kb) but I can configure it only as a "half" Hercules (1 graphics page, 32 Kb). Of course, the card has 64 Kb installed.

 

[LS120]

i have a very similar card its for a plasma luggable pc.. mine were in a transdata case with a 286-10mhz. but i have no info on it as the book it has was lost to being in water and became a solid mass of paper.

mine has the 34 pin header for plasma, and sound etc.. (seems to have a yamaha chips as well) has 9-pin D-Sub, 1 switch for mono/cga and 2nd switch for external/internal (plasma)