APPENDIX ELEVEN



53260          D00C           SIZEM
     POKE with 255 to quadruple the size of all missiles.

53268          D014           PAL
     NTSC systems have 60 frames per second and 262 lines per
     frame; PAL systems have 50 frames and 312 lines. Should read
     13 decimal, not 14.

53768          D208           AUDCTL
     Frequencies are rounded off; they are actually 63.9210 kilo-
     hertz, 15.6999 kilohertz, and 1.78979 megahertz. You can use the
     frequency to calculate the POKEY interrupt frequency by
     INTFREQ = clock frequency/(2 * (1 + value in AUDF register
     for that channel)).

     COMPUTE!'s Third Book of Atari has articles by Matt Giwer and
     Fred Tedsen on using POKEs to control the sound effects, the au-
     dio channels, and AUDCTL.

53770          D20A           RANDOM
     For example, random 0 to 9 would be INT(PEEK(53770)
     *10/256) and 0 to 99 would be INT(PEEK(53770)*100/256).

54272          D400           DMACTL
     POKE with zero to blank out screen.

54286          D40E           NMIEN
     POKE with zero, and VBLANK and system clock are disabled,
     and shadowing is suspended. See COMPUTE! magazine, June
     1983 (p. 254), for a method of trapping the RESET key in BASIC.

57344          E000           Character set
     See COMPUTE! magazine, June 1983 (p. 226).

58368-58447    E400-E44F      Handler vectors
     Each vector consists of a 15-byte table, 2 bytes each for OPEN,
     CLOSE, GET byte, PUT byte, Get status, and Special routine ad-
     dresses, The next 3 bytes are a JMP instruction followed by the
     address of the initialization routine for that handler. A zero
     separates handlers (byte 16). Here are the locations for each
     routine in the table:

     Handler OPEN   CLOSE  GET    PUT    Status Special JMP
     E:      E400   E402   E404   E406   E408   E40A    E40C
             58368  58370  58372  58374  58376  58378   58380

     S:      E410   E412   E414   E416   E418   E41A    E41C
             58384  58386  58388  58390  58392  58394   58396