Another way to use 80-column display with modern hardware is with color Composite or S-Video. This will connect to many TVs and some monitors. For this you need an RGB to S-Video or RGB to Composite adapter. There is one called the CV-04 and another by Ambery. These use RGB but no I. Which means you only get 8 colors instead of 16. If you want 16 colors (and who doesn't) then you can also (maybe) buy a "Video DAC" (try this link) or build one yourself. If you want to build one, see my webpage. Ah, hell, I included schematic if you want to build one! I also included some photos with all 16 colors for you to ponder.
Yes, ZED looks fine using S-Video. I have photo of ZED in 45 line interlace mode at this page on my website. Scroll down towards the bottom, past the color bars. Or lets see if I can put the image directly...
On my TV the top lines would get cut off using un-modified ZED. This is a problem with my TV. Many games for PlayStation and XBox will be cut off at the top too, and I have to go into game configuration and scroll the screen down a bit. Not all games have this feature of course, but they usually don't have anything import on the top row when they lack the feature...
Of course the best option would be to adjust vertical position on your monitor, but my TV does not have that option.
Edit Silly me, I didn't anwer your question. Well the characters were clear in 51-line mode, but the top ones were cut-off no matter what setting I used. In this mode, ZED generates 459 rasters, but I don't think my TV shows that many... probably closer to 450. Again this is with my TV. Your TV/monitor may be different.
Last Edit: Jul 15, 2014 20:38:09 GMT by hydrophilic: Answered the question
I'd be using the venerable 1702. The speakers still work, and it says Commodore on it. I would still be using composite for the 40 column screen, same as now with the Magnavox Pro. 45 lines is good enough really. My current monitor doesn't show the top row of the 51 line screen, or rather cuts it off. ... update, I was able to adjust vertical ht or size at the monitor and now have it all.. I guess I would try to implement your modification of the zed code if needed.
Let us not talk falsely now The hour is getting late
There was a missing line and part of a line at the top in 51 line mode. It was just my sizing of the picture vertically that I had to change. Either the Magnavox may be showing signs of age or I had changed the vertical size or position for some reason, maybe to accomodate something on the 40 columns screen but really I don't know. 51 column zed works fine. It seemed similar to the problem this monitor has with the interlace text screen that is produced by Fred Bowen's basic program from 1989.
Let us not talk falsely now The hour is getting late
He posted it on comp.sys.cbm a few years back. Pretty sure that's where it was. Way later than 88 though. However, I copied this v. and am assuming it's the same from Miro's commodore128.mirkosoft.sk/vdc.html
Then there's the... The Fred Bowen Interlaced Bitmap
100 REM 640X480 BMM (REQ. 64K VIDEO RAM!) F.BOWEN 9/88 110 : 120 FAST: TRAP410 130 SYSDEC("CDCC"),DEC("7E"),0 140 SYSDEC("CDCC"),DEC("50"),1 150 SYSDEC("CDCC"),DEC("66"),2 160 SYSDEC("CDCC"),DEC("4C"),4 170 SYSDEC("CDCC"),6 ,5 180 SYSDEC("CDCC"),DEC("4C"),6 190 SYSDEC("CDCC"),DEC("47"),7 200 SYSDEC("CDCC"),3 ,8 210 SYSDEC("CDCC"),6 ,9 220 SYSDEC("CDCC"),0 ,24 230 SYSDEC("CDCC"),128+7 ,25 240 SYSDEC("CDCC"),0 ,27 250 SYSDEC("CDCC"),16 ,28 260 SYSDEC("CDCC"),0,12 :SYSDEC("CDCC"),0,13 :SYSDEC("CDCC"),240,26 270 : rem Clear the bitmap using block fills 280 SYSDEC("CDCC"),0,18 :SYSDEC("CDCC"),0,19 :SYSDEC("CDCC"),0,31 290 FORI=0TO255:SYSDEC("CDCC"),0,30 :NEXT 300 : rem Draw a box around the border, rendering into odd & even frames 310 FORI=1TO480/2: EVEN=0+I*80-1: EH=INT(EV/256):EW=(EV-EH*256) 320 : ODD=21360+I*80-1:OH=INT(OD/256):OL=(OD-OH*256) 330 :SYSDEC("CDCC"),OH,18:SYSDEC("CDCC"),OL,19:SYSDEC("CDCA"),1:SYSDEC("CDCA"), 128 340 :SYSDEC("CDCC"),EH,18:SYSDEC("CDCC"),EW,19:SYSDEC("CDCA"),1:SYSDEC("CDCA"), 128 350 :NEXT 360 SYSDEC("CDCC"),0,18:SYSDEC("CDCC"),0,19 370 SYSDEC("CDCC"),255,31 :SYSDEC("CDCC"),79,30: rem use block fill for top of box 380 SYSDEC("CDCC"),OH,18:SYSDEC("CDCC"),OL+1,19 390 SYSDEC("CDCC"),255,31 :SYSDEC("CDCC"),79,30: rem ditto for bottom of box 400 GETKEYA$ 410 SYSDEC("E179") :SYSDEC("FF62"): SCNCLR : rem restore screen, d/l chr def's
I wanted to report about using the Ambery adapter. I originally posted you could use either the CV-04 (aka AV-04) or the Ambery adapter. This is because they both sound like they do the same thing (RGB to S-Video and Composite), and others have reported use of the Ambery adapter.
However, I did not try the Ambery adapter myself until recently when I was unable to obtain another CV-04. Well I had problems and started peeking around various CBM forums, and found that most posts claim the Ambery doesn't work at all.
Well, I eventually made it work, so I want to give everybody the details to save them a load of grief. It was pain for me because the documentation with the product is quite pathetic. It tells you acceptable INPUT FREQUENCY, Power Supply, and Output Voltages. But it does not tell you input voltages (or impedance)...
So first problem was the video sync. Although I used Ambery's 9-pin RGBI to 15-pin adapter (which has inputs for H-Sync and V-Sync), the Ambery adapter will not work with separate H and V sync. So I tried combining them with various methods. Using a XOR gate works with the GBS-8220, but not with Ambery! This is because the VDC produces Positive sync signals while the Ambery requires Negative sync (it seems the GBS-8220 works with either). Anyway, the solution was to use a second XOR gate to invert the combined sync.
With a stable display, I was still disappointed by the color of my Pull-Both circuit for 16-colors (without it, you only get 8 colors). The problem was the dark colors looked almost identical to bright colors, even when I tried cutting the resistor values in half... This was strange to me because my Pull-Both circuit worked fine for the CV-04 (S-Video adapter) and the GBS-8220 (VGA adapter). What changed?
The Ambery adapter has a much lower input impedance than the other adapters, as far as I can tell (I don't have the equipment to measure impedance). This means the Ambery was pulling on the output so "hard" that modification to voltage by my "Pull-Both" circuit had very little effect. The solution I used was to add a 220 Ohm resistor on each R/G/B line going out from circuit before it gets to the Ambery... this reduces the "pull" (increase the impedance) of the Ambery.
This produced a nice 16-color display, but I always like the color of my prototype "Pull-Down" circuit more than the previously (see first post in this thread) mentioned "Pull-Both". (Pull-Down is missing dark gray so only 15 colors... but the bright colors of "Pull-Both" are a bit "washed out".)
Anyway, I wanted to include a "brown fix" too. This is done by 74LS138 (previously published and used by others). I discovered a way to use the same chip to also generate signal for dark gray! This means with new circuit I could have better quality of "Pull-Down" and still get 16 colors like "Pull-Both". I hope you agree resulting quality is excellent....
The Ambery adapter needs Power Supply of 12V, but the chips I used (74LS138 decoder and 74F86 Quad-XOR) require 5V. This means another detail was to add a 5V power converter to my circuit (this is not needed with GBS-8220 which naturally uses 5V). So the final circuit is about 3x or 4x more complicated than original Pull-Both shown in first post of this thread.... in summary the extra factors are:
Need extra 220 Ohm (x3) resistors for Ambery impedance
Need 2 XOR gates to create Negative Composite Sync for Ambery
Used decoder (74LS138) for "brown fix" (also used for "dark gray" to give better color for all "light" colors) [not strictly needed]
Need 5V regulator circuit to use Ambery power supply
Below is a sample schematic... please note it is a bit buggy! I labeled the pin numbers from some of the XOR gates wrong (swap pin# 8 and 10, and pin# 13 and 11 to be correct) and forgot to label a resistor (left of the top XOR gate... the resistor should say "1KΩ").
Sorry the posted schema is a bit buggy, but this laptop only has generic JPG image of the schematic... I will (actually have) corrected the source file but it is on another computer at the moment. I will post the corrected version on my website along with additional images as I find the time (also awaiting feedback from user who requested this adapter).
Also interlace text mode and monochrome bitmap mode is confirmed working with the Ambery adapter. Because I only have 16K V-RAM, I have not (yet) tested color bitmap or interlaced bitmap. But I think it should work fine...
I guess the important thing to know is that Ambery adapter is more trouble than either the CV-04 or the GBS-8220.... in fact, I would say it has the problems of both added together (double trouble). I have created and shared with you a working circuit that gives excellent results (hope you agree), so it is possible to use Ambery S-Video converter with C128 (despite some comments on the web to the contrary), but I would use a CV-04 or GBS-8220 if they were available....
(P.S., you can use either the CV-04 or the Ambery adapter as a basis for a SCART converter... ask if you want details... I know there is a thread somewhere on this forum about it...)
Last Edit: Nov 27, 2015 18:11:12 GMT by hydrophilic: Typos!!