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Post by c4nnonf0dder on Aug 11, 2014 2:09:05 GMT
I have seen this somewhere else but just wanted get it out more. Alexander did me a great favor by soldering up a DAC board. My poor plastic use serves its purpose but you can see the results with the attached pics. |
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Post by hydrophilic on Aug 11, 2014 10:23:36 GMT
That looks like a board I tried, Option 2 - VGA. I mean, it does output to a VGA monitor right? I would be very interrested to know how it works with a CGA monitor! Thanks for the nice photos of the VGA? board and DAC! Do you have a screen shot of the device working? The final result (I think) is the most important thing. However I understand getting a good screen shot can be a challenge. Oh yeah, where did you get the DAC and do you know if any are still available? EditOK, now I think I get it... it works with C128 RGBI or PC CGA(EGA) as input... but it always produces VGA output. Also, I see via your first link that he is still selling them. Thanks. Very reasonable prices too (considering the small production run). I guess I should ask Alexander, because looking at the schematics in the PDF (or the web page) there is no indication how composite sync is derived; that GBS-8220 is known to be stupid and require composite sync at CGA frequencies (even though it has H-Sync and V-Sync inputs). Edit 2
Looking at close-up of your photos, and cross-referencing with Alexander's schamatic, I think I understand how he did composite sync: a 74244 + NOR Gate + OpAmp... what a strange way to do it, but if it works then cool. |
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Post by donno128 on Aug 11, 2014 12:53:42 GMT
So that's a version of Richard42's board? and produced only 70 to a 100 or so miles from me! (Scrambling to see what I can sell to afford it NOW).
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Post by cthulhu on Aug 12, 2014 9:55:26 GMT
I was thinking about getting that combo (Richard42's DAC + GBS-8200/8220). What is keeping me back is the reported un-reliability of the GBS-8200/8220 with PAL video sources.
Version 4 and 5 of that board seem to handle it better though, so I'm very tempted....
Anyway, should I decide for it, what kind of project box is the one depicted? It seems to fit both boards perfectly!
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Post by cthulhu on Nov 24, 2014 9:40:24 GMT
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Post by hydrophilic on Nov 27, 2014 5:40:23 GMT
A guy (girl?) is asking me to build RGBI to VGA using option#2 which is almost the same as this (but it uses passive resistors instead of the Richard/DAC). (S)he has not committed to purchase yet, and *I did warn* her/him that GBS-8220 is unreliable with PAL.
Most important, in my opinion, is the final product... so if you are reading this c4nnonf0dder, can you post a photo(s) of the assembled unit? I am curious to see how the menu buttons are incorporated into the case!
Anyway, if (s)he decides to purchase, I'll be sure to follow up in regards to how well GBS-8220 works with PAL C128!
Edit Thanks for the link, cthulhu! It seems your option 6b uses a GBS-8200... I am not familiar with that model, but based on the photos on the site from your link, it looks about the same as the GBS-8220. I also noticed the offer both a kit and complete unit... nice!
Another thing that got me thinking is the company is called "Microbee Technology". I seem to remember a company by that name (or very similar) back in the '80s and '90s... is it the same company that made CBM products back in the day? If so, it is amazing they have survived and continue to support CBM technology!! /Edit |
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Post by cthulhu on Nov 27, 2014 8:43:39 GMT
Another thing that got me thinking is the company is called "Microbee Technology". I seem to remember a company by that name (or very similar) back in the '80s and '90s... is it the same company that made CBM products back in the day? If so, it is amazing they have survived and continue to support CBM technology!! I don't know about them making CBM products, but here is their history. By the way, Australia's (Microbee's home country) (analog) TV standard is PAL B/G, so if they commercialize a product based on the GBS-8200 it should work, right? |
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Post by hydrophilic on Nov 27, 2014 23:46:04 GMT
Thanks for the history link. It seems they were actually a CBM competitor... with Z80 based systems back in the day. But I thought they released software for some CBMs (probably C64)... I may suffer from bad memory?
Anyway, since they are Australia based, it seems a good bet that GBS-8200 is PAL compatible...
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Post by Guest on Jan 23, 2015 22:50:39 GMT
I was lucky enough to pick up one of Richard42's original boards second hand... But just bought one of these guys as a spare.
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Post by guest on Jan 24, 2015 19:21:46 GMT
That would work, but I don't think it will fix the dark yellow issue for the C128, it would probably appear brown I would think... but for $90 complete, not a bad option. |
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