tag:blogger.com,1999:blog-6993165553021868648.post6134258768862032394..comments2024-03-27T05:39:24.505-04:00Comments on Nerdly Pleasures: 320x200 : The Resolution of Choice for the IBM PCGreat Hierophanthttp://www.blogger.com/profile/04409413307024477304noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-6993165553021868648.post-3179111960495038722022-08-23T13:02:20.750-04:002022-08-23T13:02:20.750-04:00The main reason why 320x200 pixels at 8 Bit color ...The main reason why 320x200 pixels at 8 Bit color depth was used was the addressable RAM window of 128 KiB between the memory addresses 640 and 768 of the 8086 CPU.<br />Because the 16 Bit wide address register limited the memory segment to 2^16 = 64 KiB RAM and because double buffering allowed to draw the pixels in the background while the data of other segment was displayed you have to divide these 128 KiB by two and use. Thus there was only a 64 KiB window for each buffer available.<br />And with 64 KiB this allows you to use a resolution of (64 KiB * 1024) / (320) = 204 pixels which was simplified to 200 pixel. The 320*4 Pixel that wasn't used was 1280 Bytes extra RAM that could be used for Sprite data.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-72596765777323296152022-03-03T14:48:06.029-05:002022-03-03T14:48:06.029-05:00I think I've found a workable "perfect&qu...I think I've found a workable "perfect" resolution based on this post that should work for .... 16K resolution monitors.<br /><br />9600x7200 manages to fill the vertical space of a 16K 16:9 monitor by 83%. This is close enough to be playable without too much issue. At every lower resolution, the nearest "perfect" 5:6 pixel height resolution takes up much closer to 50% of the vertical height. Since 16:9 appears to be the aspect ratio of choice for the foreseeable future, and 16K is pretty much at the upper limit of what our eyes can discern even at close range, this looks to be the best compromise we're going to get.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-28181944565801764932020-10-22T00:54:15.213-04:002020-10-22T00:54:15.213-04:00Nice! Now I understand why I can see a perfect scr...Nice! Now I understand why I can see a perfect screen ratio playing DOSBOX MK II on my LG 16:10 monitor in 1440x900 res.Danluciohttps://www.blogger.com/profile/03191086780610056854noreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-41373471068418145952016-02-18T00:46:48.771-05:002016-02-18T00:46:48.771-05:00I miss my Amiga 1000 and Guru Meditation!I miss my Amiga 1000 and Guru Meditation!Miguelhttp://www.falconitservices.comnoreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-17266722492972811712014-02-08T15:51:30.233-05:002014-02-08T15:51:30.233-05:00FWIW, Amiga games using 320x200 was mainly to cate...FWIW, Amiga games using 320x200 was mainly to cater to NTSC Amigas, which used 320x200 with 4:3 screen aspect ratio but 8:9 pixel aspect ratio vs. PAL Amigas which used 320x256 displays with 4:3 screen aspect radio but 16:15 pixel aspect ratio. See e.g. <a href="http://amiga.lychesis.net/knowledge/ScreenModes.html" rel="nofollow">this reference</a>.<br /><br />So it wasn't actually primarily some sort of speed hack, though technically did have minor advantages there as bitplane DMA could end earlier freeing up more chip memory bandwidth for other things (the Amiga had a partially-UMA system with the cpu and several gfx/sfx/io coprocessors sharing a memory bank. Memory used by all processors was called "chip memory" (used by the custom coprocessor chipset as well as the CPU), memory accessible to the CPU only was called "fast memory" (as it was faster from the CPU's perspective) - a lot of amigas only had chip memory out-of-box. Different generations of Amiga have different maximum chip memory sizes, from 512kiB to 2MiB (with nearly-but-not-quite-released Amiga designs going to 8MiB so some emulators support that).<br /><br />PAL Amiga users generally kind of hated they way some Amiga games would just use 320x200-only as it would be letterboxed and slightly distored looking on their displays. Good games developers sometimes allowed proper switching. OTOH, european Amiga games might be 320x256-only and the NTSC guys would get a cut-off display (but the Amiga was far, far more popular in Europe than America of course...)<br /><br />The Amiga had crazy powerful (for the era) programmable gfx hardware including quite a bit of ability to adjust actual pixel/scanline timings, and even sync to an external clock signal. This made them very popular in the video processing world of 1980s and 1990s TV/Movie industry as they could <a href="http://en.wikipedia.org/wiki/Genlock" rel="nofollow">genlock</a> and <a href="http://en.wikipedia.org/wiki/Chroma_key" rel="nofollow">chroma-key</a> with (relatively) inexpensive hardware add-on (like the famous <a href="http://en.wikipedia.org/wiki/Video_Toaster" rel="nofollow">"Video Toaster"</a>)<br /><br />A lot of amiga modes used very-non-square (roughly 2x1) pixel aspect ratios to have more horizontal resolution. And of course the cursed flickery interlacing (showing alternate scanlines every frame) for simulated double vertical resolution. Ultimately most modes ended up with an actual screen aspect ratio of 4:3 even if they were something deeply weird like 1280x256.<br /><br />The Amiga could also be coaxed into "overscanning" so that it filled the display right to the edges of the PAL or NTSC video signals instead of being a rectangle with borders. It did this by adding more pixels (e.g. 704x484 NTSC / 704x576 PAL), not making the pixels bigger, so detail wasn't lost.<br /><br />I think it might have also been able to output analog-era-widescreen-tv-suitable signal, but hazy on that.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-21523234865581642212013-11-19T01:19:18.390-05:002013-11-19T01:19:18.390-05:00No, I meant letterboxing. Letterboxing is the sta...No, I meant letterboxing. Letterboxing is the standard aspect-ratio correct method to show widescreen material on a full screen display. 320x200 with square pixels is a widescreen mode. Pillarboxing is the standard aspect-ratio correct method to show full screen material on a widescreen display. Great Hierophanthttps://www.blogger.com/profile/04409413307024477304noreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-44753165359702488892013-10-15T19:37:27.677-04:002013-10-15T19:37:27.677-04:00"must have letterboxing" -- I think you ..."must have letterboxing" -- I think you meant pillarboxing.Trixterhttps://www.blogger.com/profile/14920796808766570708noreply@blogger.comtag:blogger.com,1999:blog-6993165553021868648.post-7851802798113905792013-10-13T13:03:24.639-04:002013-10-13T13:03:24.639-04:00I always look forward to your posts for the breadt...I always look forward to your posts for the breadth of information you provide. Raifieldhttps://www.blogger.com/profile/08478524519453417677noreply@blogger.com