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16 votes

How does Quake 1 access video memory in software mode?

When running in software mode, Quake uses SciTech's MGL. The screen buffer is locked using VID_LockBuffer which calls MGL_beginDirectAccess: void VID_LockBuffer (void) { ... ...
aybe's user avatar
  • 7,102
12 votes

NTSC scan lines used by 8-bit computers

I found one document which might shed some light why 192 lines was used before 200 caught on. The TI 99/4 used a TI TMS9918 VDP, which based on the document, was designed as a chip for simple low cost ...
Justme's user avatar
  • 33k
10 votes

NTSC scan lines used by 8-bit computers

Older television sets used round picture tubes with a bezel to mask off the edges of the scanned area. Picture tubes were often circular, and to maximize useful areas, the image was expanded to the ...
supercat's user avatar
  • 36.6k
10 votes

NTSC scan lines used by 8-bit computers

Conjecture #1: NTSC title-safe area (unlikely) An NTSC video frame has 525 lines. After subtracting the 21 lines of vertical blanking, and the 20% of the visible area that was considered non-title-...
dan04's user avatar
  • 1,084
10 votes

NTSC scan lines used by 8-bit computers

Similar to the TI VDP answer, have a look at the Apple text mode layout described in this answer. (And keep in mind that the graphics video layout is based on the text layout). There are 40 characters ...
dirkt's user avatar
  • 27.9k
4 votes

How do I wait for end-of-frame (VSYNC) on a TRS-80 models 1 and 3?

There's no way to do it on the Model 1. The Model 3 has an interrupt that triggers every second vsync. Bit 2 of I/O port $E0 set to 0 indicates when the interrupt is active and can be enabled by ...
George Phillips's user avatar
3 votes

Are there any trapdoor slot video cards for a non-tower Amiga 1200?

A PiStorm Lite will let you use a Raspberry Pi 3 or 4 as a CPU accelerator, and now allow the HDMI output of the Pi to be used as a graphics card
Zenzizenzizenzic's user avatar

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