***************************************************************
*                                                             *
*      Module Name: WRITRACK.LIB         Rev. 1.00            *
*      Function: Write an entire track   Last rev. 06 May 85  *
*         at one shot from memory.       By: glh/w6bsk        *
*                                                             *
***************************************************************


cmdreg    equ       0e3fch    ; 1791 command port
datreg    equ       0e3ffh    ; 1791 data port
wrtcmd    equ       000f4h    ; Write track command

wrttrk:
          call notbsy         ; Wait until 1791 idle
          lxi  d,datreg       ; Point to 1791 data port
          lxi  h,trakbuf      ; and to source code.
          mvi  c,24           ; Set number of pages to be
wrtpag    equ  $-1            ; written to disk
          mvi  a,wrtcmd       ; Get and issue a write
          sta  cmdreg         ; track command.
          xchg                ; Swap the pointers-

wrtlup:
          ldax d              ; Get a data byte and dump 
          mov  m,a            ; it into the 1791. Then
          inr  e              ; update the byte pointer to
          jnz  wrtlup         ; the next cell and continue
          inò  ä              »  untiì thå entirå buffeò haó �
          dcr  c              ; been written to disk : one
          jnz  wrtlup         ; entire track's worth.
          ret

trkbuf    ds   17ffh          ; This must be dumped if the  
                              ; READTRAK file is installed.