IBM
This clone CGA/MDA card has a couple of surprising
This clone CGA/MDA card has a couple of surprising hidden features
#clone #CGAMDA #card #couple #surprising
“Adrian’s Digital Basement ][”
You might look at this 8-bit ISA card and just think it’s another run of the mill CGA/MDA clone card, but it turns out there are some …
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The board also appears to have another place for headers. It is located to the right side of the left-most ASIC. I also wonder what was the purpose of the unpopulated U1 in the top left corner of the board.
skip to about 19 min in if you just want to get to the point
The fact that it displays 720×350 in text mode color makes me wonder if this one is a limited Hercules InColor clone, which was basically a color version of the Hercules. Is there any software or games that use those modes?
Wow. Color in Hercules mode. Now I've seen everything. This is insane!. It's like if somebody told me "CGA can do 640×480 at 256 colors", I thought "hercules can't do color" was like a natural law of the universe hahaha.
0:26: 🕹️ Unveiling unique features of a vintage VTEC 8bit Isa video card from Hong Kong.
3:59: ⚙️ Analysis of modifications made to a clone CGA/MDA card, including trace cutting and resistor connections.
8:42: 🎨 The clone CGA/MDA card offers surprising compatibility with various color palettes and 6845 programming.
12:31: ⚙️ Issues with color output on CGA card due to motherboard clock frequency mismatch.
16:29: 🎨 Unexpected features of CGA/MDA card allow for accurate artifact color decoding, enhancing old game visuals.
20:08: 🎨 The clone CGA/MDA card has hidden Plantronics compatibility for 16-color graphics support.
24:20: ⚙️ A clone card designed for CGA has hidden features for MDA compatibility.
28:27: ⚙️ Hidden features of a clone CGA/MDA card include potential color support on monochrome video signal.
32:41: 🌈 Exploration of color output on modified IBM MDA card and program behavior when BIOS settings are ignored.
Timestamps by Tammy AI
I wonder if you could add a capacitor to the crystal to fine tune the clock.
In addition to kids technology, VTech also made PC clones that were sold in Canada. In the mid/late 90s, they split off their PC division which rebranded under "Tandex". The company I worked for at the time was their largest retailer (we started selling them after Commodore filed for bankruptcy.) I think this card was for an early model, as the ones we sold all had integrated video. (We started selling them around the time the 486DX was the "standard".)
Thanks Adrian! Cool gpu!
Link to the card itself? I'd love to see how my Multisync II takes this.
*Edit oops for some reason I thought this was a new CGA card via Aliexpress or whatever.
I was super excited to watch this video and it did not disappoint. I love these interesting topics most others wouldnt cover. Thank you for the detailed info and history. The deep dives are rare and refreshing.
A nice little card indeed!
Ohh that card is cool. If they would have sold it with the features advertised it would have been system builders #1 pick at the time. Now I have to wonder if it maybe has some sort of color hi-res mode hidden in there somewhere.
I have an ATi Small Wonder CGA/Hercules gfx card that also supports Plantronics mode, no jumpers needed 🙂. Plantronics mode doesn't need 64KiB btw, just 32 (double the CGA memory). It has an extra "bit" plane, that actually holds two bits per pixel: the blue and intensity bits (the normal CGA memory still has the red and green bits).
Colour MDA, a neat trick. The character attribute bytes in the frame buffer have mostly the same format in monochome and colour modes, no doubt IBM did this to make it easier to write software (mda uses any non white background colour is black and any non black foreground is white which meant coloured text on the same colour background should be readable in true MDA but unreadable in colour, not very useful but something you'd put in a conformance test, the cga tester has a test with text on same colour background and the monochome output should reveal the text that can't be seen when using color if it's properly compatible with MDA). Ultimately the timeframe for this trick being useful would have been very short as EGA had highres colour text and then vga happened boosting the res again. Changing a vga card into cga text mode, ugh, its just all sorts of wrong
the CGA 'gray' palette consists of a color set that has optimal Luma separation on composite. (which means that it gives the best grays on monochrome composite in 320×200 mode)
I wonder what the code in the Video BIOS looks like and if that might reveal any other new modes which were undocumented? 😁🤷♂️
Maybe it even supports Hercules InColor?
You speak way too quickly in this video. Cool down a bit. I can follow but it's stressful. Love your uploads otherwise!
The 245N!
What I know about Vtech is for little kids and up too 12 years old electric toys
The grayscale 320×200 option in Planet X3 is working correctly. On a composite monitor it disables the color burst, giving artifact-free grayscale video, but on an RGB monitor it still shows up in color, with the magenta color replaced by red.
WOW! I wish knew this back in the day. I think they purposely did not allow this mode due to copyright infringement.
This reminds me of YouTuber @pcretroprogrammer2656. He goes super deep exploring the functionality of some of this old video hardware. It would be interesting to see him take a look into the hidden features of this card.
Based on others' comments, it seems IBM intentionally hobbled the colour mode as not to affect sales of other models they were selling, rather daft policy that, "We have this great product here, and it can do so muchat a low cost, buuuuuut, we want people to buy the super-expensive stuff instead so just neuter it!!!", shot themselves in the foot there I'd say… :S
VTech kept making computers until at least the mid 90s. I have a Laser 486 with a VTech chipset on the motherboard (and weird SystemSoft BIOS that freezes with Speedsys).
I wish we (vintage computer community) could get the expense of a RGB/CGA TTL-to-VGA/HDMI convertor (like the open project created by Hoglet67) down. $100+ is too expensive.
V-Tech had a history of having weird modes, even in the Laser 128. Back in the 80s I had a Laser 128 and managed to get it to display a double-hires screen that was double-stacked vertically, then made a paint program for it.
That's pretty cool!
wohoo Plantronics!
Composite NTSC = YUCH!!!!. Gimme PAL any day. It was worth the wait here in Europe for PAL to finally arrive. 625 lines and colour at 4.43MHz