Retro raster timing

Pick a machine. The preset fills in the clock, raster units per line, and lines per frame — you can change any of them (for example to model an overscan or a 60 Hz switch) and Reset values puts them back.

Frame gives cycles per line and per frame, the frame and line rates, and how long a scanline and a single cycle take.
Convert turns CPU cycles, raster units, microseconds, scanlines, or frames into all the others.
Raster-time budget: enter how many CPU cycles your routine takes per frame to see how much of the frame it uses, after the DMA estimate below.
DMA estimates the cycles video hardware takes from the CPU: Amiga bitplanes by depth and resolution, Atari 8-bit ANTIC modes, playfield width and player/missile graphics, and C64 badlines and sprites.

Reference numbers

Machine	Clock (Hz)	Per line	Lines	Frame rate
Amiga PAL	3,546,895 (colour clock)	227	313	49.92 Hz
Amiga NTSC	3,579,545 (colour clock)	227.5	262	60.05 Hz
Atari ST 50 Hz	8,021,247	512	313	50.05 Hz
Atari ST 60 Hz	8,010,613	508	263	59.96 Hz
Atari ST mono	8,021,247	224	501	71.48 Hz
Atari 8-bit PAL	1,773,447	114	312	49.86 Hz
Atari 8-bit NTSC	1,789,773	114	262	59.92 Hz
C64 PAL	985,248	63	312	50.12 Hz
C64 NTSC	1,022,727	65	263	59.83 Hz

One Amiga colour clock is two 68000 cycles. The DMA figures are simplified models — good for a first estimate, not cycle-exact: Copper and blitter contention, ANTIC’s exact slot pattern, and C64 sprite fetch details are approximated.

Share link copies a link with the system, its timing values, the conversion, the raster budget, and the DMA settings. All are readable parameters: ?sys= (amiga-pal, amiga-ntsc, st-pal, a8-pal, c64-pal, …), ?clock=, ?perLine=, ?lines=, ?conv= and ?from= (cpu, units, us, lines, frames), ?budget=, and the DMA options (?planes=, ?hires=, ?vis=, ?antic=, ?width=, ?pm=, ?bad=, ?spr=) — for example ?sys=c64-pal&budget=8000.

Reference numbers

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