ATARI DISPLAY

Video Timing Diagram

                         
             
Hsync
(16)
Color
burst
(12)
Porch
(6)
(30) Narrow Playfield
128 Colour Clocks
(30) Porch
(6)
   
(14) Standard Playfield
160 Colour Clocks
(14)
(10) Wide Playfield
176 Colour Clocks displayed
(192 Colour Clocks Read)
(2)
0:15 16:27 28:34 34:43 44:47 48:63 64:191 192:207 208:219 220:221 222:227 228 Colour clock cycle
0:7 8:13 14:16 17:21 22:23 24:31 32:95 96:103 104:109 110 111:113 114 CPU cycles

Atari Timing Values

(1) NTSC colour carrier 35/44 * 4.5 MHz = 3.5795454545... MHz by definition
  CPU clock = (1)/2 35/88 * 4.5 MHz = 1.78977272... MHz by

Atari FAQ says:
NTSC machines: 1.7897725 MHz
PAL machines: 1.773447 MHz

  1 machine cycle 0.5[587301 recurring]
  1 scan line =
228 colour clocks
114 CPU clocks
63.6[952380recurring] us
= 15699.[760765550239234449]Hz
  1 frame =
262 scan line =
228 colour clocks
29868 CPU clocks
16688.1[523809 recurring] us
= 59.9227510135505314291975601738559 Hz
  60 frames
= 1 second nominally
1001289.[142857 recurring] us
     
     
     
     
  VBLANK time = 7980 machine cycles or less, depending on GRAPHICS mode.
The shortest 6502 instruction requires two cycles;
during that time the electron beam moves four color clocks.
  Horizontal blank time:  
  Wide playfield 18 machine cycles
  Normal playfield 34 machine cycles
  Narrow playfield 50 machine cycles
 

See the Hardware Manual for more information on cycle counting

to display horizontal lines.

Standard Frames
/ sec
Fields
/ sec
Lines/
frame
Lines
/ sec
Ás
/line
 
PAL 25 50 625 15625 64 Ás exactly  
NTSC 30 60 525 15750 63.492 Ás.  

For simplicity, this discussion will assume 64