tag:blogger.com,1999:blog-6808222767258036800.post2790347785054656925..comments2023-06-04T03:36:41.963-07:00Comments on 8088 MPH: CGA in 1024 Colors - a New Mode: the Illustrated GuideUnknownnoreply@blogger.comBlogger18125tag:blogger.com,1999:blog-6808222767258036800.post-49642248492253137802017-12-05T15:11:42.876-08:002017-12-05T15:11:42.876-08:00@Ed Coolidge: if you could use different bit patte...@Ed Coolidge: if you could use different bit patterns on every scanline, you would have the same "palette" at double the resolution (80x200 'pixels'). But at two scanlines per character row, the non-programmable CGA font doesn't give us a free choice of such patterns to use... and if you go for one scanline per row, a full-screen picture would need twice as much RAM as the CGA's 16K. The "mugshots" section of 8088MPH (before the end credits) does exactly that, which is why it only covers half the screen. :)<br /><br />The mentioned hack that we didn't use has to do with modifying the card's color registers at particular scanlines, but that only works in graphics mode (in text mode it'd only affect the border/overscan color, not the active area). Anyway, that trick still gets you 16 colors per scanline at most. VileRhttps://www.blogger.com/profile/16639821897403585503noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-17283111310976362762017-12-02T23:00:40.435-08:002017-12-02T23:00:40.435-08:00If switching between alternating fields was used t...If switching between alternating fields was used to produce the same solid color on both scanlines, what would you get if it was used to set a different bit/color pattern on each scanline separately? I know you said reenigne could use that hack, but didn't. What if you added that hack too? Anonymoushttps://www.blogger.com/profile/05594843814343956136noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-17873127920483649952017-09-19T09:22:38.472-07:002017-09-19T09:22:38.472-07:00Jesus Christ!!! As a former amateur programmer, I ...Jesus Christ!!! As a former amateur programmer, I came here from a different thread: C64 raster-handling tricks which I guessed for long but never found explained until now. But 1024 CGA is simply genius stuff. Absolute respect and admiration to people involved.Olliehttps://www.blogger.com/profile/16224656529852264534noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-62869707687744794902017-05-13T11:29:40.034-07:002017-05-13T11:29:40.034-07:00Unbelievable. I was browsing Google for some help ...Unbelievable. I was browsing Google for some help with ANSI text and found this page by accident. It doesn't even seem possible!MDVnoreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-4283100692728770832017-04-10T08:32:00.801-07:002017-04-10T08:32:00.801-07:00Saint Mary Francis!
My jaw just unlocked and fell ...Saint Mary Francis!<br />My jaw just unlocked and fell of 8()Unknownhttps://www.blogger.com/profile/05939874807869548669noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-75098536124829900522017-03-30T17:53:45.975-07:002017-03-30T17:53:45.975-07:00It's almost 3 at night here, and I should be s...It's almost 3 at night here, and I should be sleeping, but I just had to read through this entire writeup. This is absolutely amazing, great work!kluttpendylhttps://www.blogger.com/profile/14289043255810415430noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-86419989483576869392017-01-08T13:28:33.754-08:002017-01-08T13:28:33.754-08:00Would it be possible to package up the 1K CGA mode...Would it be possible to package up the 1K CGA mode drawing code into a library?Anonymoushttps://www.blogger.com/profile/07008586540353260459noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-90716772020976133302015-10-28T21:23:29.210-07:002015-10-28T21:23:29.210-07:00Twice as fat...Twice as fat...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-67178045769904142462015-08-11T07:57:04.941-07:002015-08-11T07:57:04.941-07:00BLuRry: thanks for the feedback!
Funny that you m...BLuRry: thanks for the feedback!<br /><br />Funny that you mention Apple ][ NTSC emulation, as I just put up a new post on that subject - to be fair, I wasn't aware of JACE until now, so I didn't consider it when writing that post. I'll have to give it a go with those demos you mention :-)VileRhttps://www.blogger.com/profile/16639821897403585503noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-77602559621373856622015-08-11T07:40:33.396-07:002015-08-11T07:40:33.396-07:00As an emulation author, I have done quite a bit of...As an emulation author, I have done quite a bit of study on how to emulate the NTSC color fringe using sliding windows. Your description of the artifact behavior is spot-on and well-done! It might help the folks at home to look at YU'V-to-RGB conversion formulas in order to better understand the math involved. But discovering how to use other colors in text-mode, that's just outstanding!<br /><br />As it turns out the color fringing behavior is present in Apple // graphics as well, just never really utilized. A blue pixel fades in/out of black and so on. You could represent the apple screen as having 560x192 resolution, but some pixels come out as different colors despite the apple only produces 140 color cycles -- if you move a single pixel from left to right it will still appear as if it were in 560 places, it will just change colors along the way.<br /><br />The best way I could exploit this is by a brute-force method, where my goal is to find the best combination of bits (the apply uses 7 out of every byte) to represent 7 input pixels. I just look for the shortest (perceptive) color difference for a group of 7 pixels, turning on each bit on and off one by one. Then using dithering I spread the error to the pixels below, etc. This has a nice side-effect of giving me the fullest color representation of an image while retaining 560 pixel-width detail. No you can't see it on a TV screen clearly but it looks nice and smooth all the same.<br /><br />Anyway, well-done. You guys are clever gents! When you get a chance, have a look at some of the recent graphics demos by "French Touch" who have been able to do some crazy graphics hacks on the Apple // series (especially their "Crazy Cycles" demo which will break most emulators but not mine. ;-)BLuRryhttps://www.blogger.com/profile/13222469217905973880noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-76672439079099370882015-04-27T14:23:19.276-07:002015-04-27T14:23:19.276-07:00Beautiful and informing.Beautiful and informing.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-34900362401192269622015-04-22T19:50:38.083-07:002015-04-22T19:50:38.083-07:00You remember correctly - CGA Frogger starts each f...You remember correctly - CGA Frogger starts each frame with a blue background, and sets it to black at a particular scanline down the screen. Jungle Hunt and California Games did similar things (all rely on rather precise timing and/or polling the CGA status register, since there are no raster interrupts).VileRhttps://www.blogger.com/profile/16639821897403585503noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-21683318166234329662015-04-22T15:12:30.612-07:002015-04-22T15:12:30.612-07:00Cool.
As far as I remember, "frogger" ga...Cool.<br />As far as I remember, "frogger" game for CGA used 5 different colors. How exactly it was done, I wonder.Slyhttps://www.blogger.com/profile/07190581414534392208noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-47358827839282855292015-04-17T14:49:26.950-07:002015-04-17T14:49:26.950-07:00Having implemented the Woz-style 16-color mode (in...Having implemented the Woz-style 16-color mode (including the Y'UV conversions) I have to say hats off to you guys for pushing the limits. Excellent write-up too!BLuRryhttps://www.blogger.com/profile/13222469217905973880noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-91210454463567128002015-04-16T14:38:04.907-07:002015-04-16T14:38:04.907-07:00Sir, I am honoroured to live in the same Standard ...Sir, I am honoroured to live in the same Standard History Eventline as you do. It all sounds so obvious. <br /><br />I wonder what ingenious guys like you could do with a 1978 near-defunct Hardware. In space. Like ICE/ISEE-3.<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-48716222382306141492015-04-16T13:30:10.012-07:002015-04-16T13:30:10.012-07:00*Amazing*. This crushes anything I achieved with m...*Amazing*. This crushes anything I achieved with my graphically superior C64 using scan line manipulation - and I thought I was a genius at the time. *sobs*Matthew Sweeneyhttps://www.blogger.com/profile/06159570713388092494noreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-65397305634579892152015-04-16T13:17:25.493-07:002015-04-16T13:17:25.493-07:00Lovely! :)Lovely! :)Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6808222767258036800.post-61298979278329360312015-04-16T10:21:35.925-07:002015-04-16T10:21:35.925-07:00Absolutely brilliant. Thanks for this detailed wri...Absolutely brilliant. Thanks for this detailed write-up !Ange Albertinihttps://www.blogger.com/profile/17423188298352515655noreply@blogger.com