C P / M   6 8 0 0 0   A s s e m b l e r		Revision 02.01		Page   1
Source File: clockset.s

   1                                
   2                               
   3                               *****************************************************************
   4                               *                                                               * 
   5                               *    MORROW 68K SYSTEM clock routines                           * 
   6                               *                                                               *
   7                               *****************************************************************
   8                               
   9                               
  10                               *******************
  11                               *  E Q U A T E S  *
  12                               *******************
  13                               
  14                               ioaddr  =       $ff0000                 * compupro 68K i/o address space
  15                               
  16                               
  17                               base    =       ioaddr+$48              * standard base address
  18                               grpctl  =       base+$7                 * select port
  19                               group0  =       8                       * clock group select constant
  20                               
  21                               clock   =       base+2                  * clock address within group 0
  22                               
  23                               tp64    =       $10                     * constant for 64 Hz
  24                               clkstb  =       $20                     * strobe inactive
  25                               
  26                               
  27                               ****************************
  28                               *   B E G I N    C O D E   *
  29                               ****************************
  30                               
  31                               * Routine sets the interrupt rate to 64 time per second
  32                               
  33 00000000 13F8000800FF004F     setit:  move.b  group0,grpctl           * select group 0
  34 00000008 13F8001000FF004A             move.b  tp64,clock              * send 64 Hz constant strobe low
  35 00000010 4E71                         nop                             * stall for slow hardware
  36 00000012 4E71                         nop                             *   -minimum of 2.0 us
  37 00000014 4E71                         nop                             *   -for data setup time
  38 00000016 13F8003000FF004A             move.b  tp64+clkstb,clock       * send 64 Hz constant strobe high
  39 0000001E 4E71                         nop                             * stall for slow hardware
  40 00000020 4E71                         nop                             *   -minimum of 2.0 us
  41 00000022 4E71                         nop                             *    -for data hold time
  42 00000024 13F8001000FF004A             move.b  tp64,clock              * send 64 Hz constant strobe low
  43 0000002C 4E75                         rts
  44                               
  45                               
  46                               * Routine clears the clock interrupt
  47                               
  48                               clearit:
  49 0000002E 13F8000800FF004F             move.b  group0,grpctl           * select group 0
  50 00000036 103900FF004A                 move.b  clock,d0                * read clock, clear interrupt
  51 0000003C 4E75                         rts
  52                               
  53 0000003E                              .end
C P / M   6 8 0 0 0   A s s e m b l e r		Revision 02.01		Page   2
Source File: clockset.s

S y m b o l   T a b l e

base      00FF0048 ABS   clearit   0000002E TEXT  clkstb    00000020 ABS   clock     00FF004A ABS   
group0    00000008 ABS   grpctl    00FF004F ABS   ioaddr    00FF0000 ABS   setit     00000000 TEXT  
tp64      00000010 ABS    roup0    00000008 ABS   grpctl    00FF004F ABS   ioaddr    00FF0000 ABS   setit     00000000 TEXT  
tp64      000000