Timeline for How do DOS games like DOOM benefit from a PCI graphics card?
Current License: CC BY-SA 4.0
8 events
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| Aug 6 at 5:38 | history | edited | Alex Cannon | CC BY-SA 4.0 |
Added Windows VGA driver example at the end.
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| Aug 3 at 17:38 | history | edited | Alex Cannon | CC BY-SA 4.0 |
added 7 characters in body
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| Aug 3 at 12:59 | comment | added | Alex Cannon | If 5MBps would allow for 30 FPS on ISA, then the same CPU could do 59 FPS on PCI. The big issue is the CPU can't do anything else while writing to the video buffer. If a PCI or AGP device is just as fast as RAM, then the CPU becomes the bottle neck and having a faster bus won't make any difference beyond that point. | |
| Aug 3 at 11:33 | comment | added | Lou Knee | > It's hard to find information about how fast an ISA graphics card's memory can be accessed I think that's because it's totally card dependent: all that the CPU sees is a 64k buffer and a controller chip - it's down to the card to move things around to "clear space" for the next 64k. Giving the graphics chip direct access to system RAM (which is the opposite direction) was one of the magic powers AGP was supposed to have. | |
| Aug 3 at 8:38 | comment | added | Stephen Kitt | 5MBps is still significantly higher than 2MBps — and yes, it is slow for graphics, but it’s fast enough for PCs back then (memory bandwidth wasn’t huge either). More importantly, it’s quite a bit more than the bandwidth required for 320×240, and more still than that required for 320×200 which is the resolution used in most games! Scroll slightly further down in the discussion on Vogons and you’ll see someone mention 6.5MBps on a Compaq 386, which is closer to the expected maximum of 8MBps (which was probably unattainable). | |
| Aug 2 at 20:38 | comment | added | Alex Cannon | @Stephen Kitt, in this discussion at vogons.org/viewtopic.php?t=99874&start=20 , the user bakemono says that 3 clocks per word and 5MB/sec is the best they've seen from an ISA device. 5MB is still really slow for graphics! It's hard to find information about how fast an ISA graphics card's memory can be accessed. | |
| Aug 2 at 18:28 | comment | added | Stephen Kitt | The article you link to mentions 2MBps as a typical speed (without specifying what “typical” means); a 16-bit ISA bus supports significantly higher rates even at the “standard” 8MHz. | |
| Aug 2 at 15:08 | history | answered | Alex Cannon | CC BY-SA 4.0 |