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Post by mrbombermillzy on Nov 26, 2019 9:02:00 GMT
Nice screen mockup and palette shades diagram Oziphantom!
Regular dithering should allow something like 240 colours.
Please continue Oziphantom with the mockups!
Perhaps you could swap the colours on the 2nd (interlace) frame to get an even smoother colour graduation? You would have to take a photo at a slower shutter speed to show us the actual visible colours though.
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Post by mrbombermillzy on Nov 25, 2019 21:42:16 GMT
For some reason, I keep thinking the NTSC C128's can output colour composite CGA... I must be getting rusty! At a bare minimum though, 16 new colours are available using this method:
Im not sure if this will be consistent on non CRT output devices though.
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Post by mrbombermillzy on Nov 25, 2019 19:34:52 GMT
Hi all.
Basically, they are using an old IBM MC6845 CRTC based chip, which is very similar to the C128 VDC (well close enough to be able to effectively achieve the same results).
However, dont everyone get too excited, as its only for NTSC composite output. That, and the H and V resolutions get a bit hammered. However, it may be good news for any of our American friends here!
Just thought I'd share here, as it looks like this hasnt been discussed here yet.
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Post by mrbombermillzy on Nov 25, 2019 13:46:35 GMT
Where can I get the 8568 VDC status program? -Thom Hi Pyrofer and Thom! Sorry for the late reply, didnt notice this thread had grown and it has been a good while since I last touched base, so... Unfortunately, I have been totally unable to pick up a working ~240v C128DCR PSU. That may well be where the machine resetting issues I have had stem from. Without this I am unable to continue with any 'work'... had to sell my other 2 working 128D's after the house move. @thom: I cant copy my physical floppy with my test program on it ATM.. Apologies, but its just a little BASIC program I quickly knocked up, so nothing special anyway. @pyrofer: As for the info Pyro, at least from my mad hacks, I documented everything I tried here in my other thread (apart from a 1280x200 test and some text on the flyback beam when pushing Hsync values!), along with some extra info at the start of this thread. However, Im not in the position to continue, as mentioned above. Continuing would have been trying what I had discovered on safer TFT screens, which are less delicate (or at least less costly!) than CRT monitors. It seems C128's are starting to get really expensive to buy all of a sudden, so my 128DCR looks likely to be sat in limbo for quite a while yet. Perhaps I will look into Willymanillys C128/VDC emulator, though Im not sure how 'bleeding edge' the compatability is. Anyway, if theres anything you need answering from my old test thread, just PM me or reply here. I will get to it...sooner or later! lol!
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Post by mrbombermillzy on May 20, 2018 20:32:56 GMT
I have an NEC multysync 1990FXp that I purcased with the sole intent of replacing the half dozen (im not joking) CRT monitors that I have lying around for the older systems that I own. It does a fair job for most stuff 15Khz upwards. However, it doesnt cope with the more 'custom' scan rates in the 20-30khz range, or any interlace modes, which makes it a bit trickier to use on an Amiga. IMHO, any LCD will make a poor substitute for any CRT on the C64/128, especially graphics/demos that use the colour/pixel bleed/blur of a CRT to advantage. My C64 stuff looks awful on my Panasonic Plasma TV too Then theres the frame delay to think about as well... Err, not to get too negative about it all, the above mentioned NEC does ok! Also, there is an Atari ST list with LCD's that will work on C64/128 if the description says they do low/med res on ST: www.atari-wiki.com/index.php?title=Flat_Panel_Displays&action=editUnfortunately, the site has been broken for a while, so the above source view link will look a bit rough. However, you get a little description for alot of the monitor display results, which can be handy. Lastly Molebrain, I wasnt clear about what you are using the monitor for. If its for the VICII/e outputs, you may have to get something with a composite/s-video input, as most will only take analog RGB input or DP/DVI/HDMI, any of which a UK or USA C64/128 system does not output (unless they are TFT TV monitors, which should have a built in converter/upscaler circuit and RF, COMP and SVID inputs). I have heard that the French C64s had an RGB output, but I believe they had a Composite to RGB converter on the mainboard, so the quality wasnt great (Ive never come across any so cant confirm..Any French C64 owners reading this?). And I THINK that they would only display B/W on a PAL system anyway as they used PERITEL which is a bit different signal wise.
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Post by mrbombermillzy on May 1, 2018 21:09:23 GMT
...In the meantime, here is a little code snippet (courtesy of Craig Bruce) which sets up the VDC for 640x491 interlaced monochrome bitmapped mode. Not too far off what you are looking for really. HTH:
.$1329 [a0 00 ] ldy #$00 .$132b [be 4a 13] ldx $134a,y .$132e [b9 5e 13] lda $135e,y .$1331 [e0 19 ] cpx #$19 .$1333 [d0 08 ] bne $133d .$1335 [20 1b 13] jsr $131b ;read VDC register #.X into .A .$1338 [29 0f ] and #$0f .$133a [19 5e 13] ora $135e,y .$133d [20 0f 13] jsr $130f ;write value .A into VDC register #.X .$1340 [c8 ] iny .$1341 [c0 14 ] cpy #$14 .$1343 [90 e6 ] bcc $132b
$134a: 00 01 02 04 05 06 07 08 09 18 19 1b 1c 14 15 0c 0d 1a 0c 0d
$135e: 7e 50 66 4c 06 4c 47 03 06 00 80 00 10 a6 e0 00 e0 00 00 48
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Post by mrbombermillzy on May 1, 2018 20:38:11 GMT
OK, I will try my best to get it to you. I imagine if you are going to use both the VDC bitmapped mode and the C language to drive the display, you may not get ultra fast screen updates. Not sure if this is needed for an old teaching system..?
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Post by mrbombermillzy on May 1, 2018 19:08:12 GMT
Do you mean the one in the photos from my high resolution thread mentioned above?
If so, thats a program that I cobbled together to change the VDC registers quickly without having to type in the peek/pokes 'blind'. It also shows the status of each register, but only the combined byte values, which is ok for most of them anyway. Perhaps I will upgrade this at some point if necessary.
I can probably put in onto the SD2IEC this weekend (from the floppy) if this is what you are after?
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Post by mrbombermillzy on Apr 30, 2018 20:57:03 GMT
Shock! Horror! Did the C128 get the first ever port of it?! lol
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Post by mrbombermillzy on Apr 30, 2018 20:51:58 GMT
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