2,009 bytes added,
22:52, 12 March 2007 <pre>
;; This example shows how to read a sector from
;; a DATA format disc
;;
;; This code is public domain and can be used in your
;; own programs.
;;
;; Written by Kevin Thacker, 2002.
;;
;;------------------------------------------------
;; firmware function to find a RSX
.kl_find_command equ &bcd4
org &8000
nolist
;;------------------------------------------------
;; find BIOS: READ SECTOR command
;;
;; This method is compatible with other DOSs that
;; override or provide this command. If the command
;; is not found, then there is no furthur action. Therefore
;; on tape based systems, this code will have no effect.
ld hl,cmd_bios_read_sector
call kl_find_command
ret nc
;; command found
;; store address of command
ld (bios_read_sector),hl
;; store "rom select" of command
ld a,c
ld (bios_read_sector+2),a
;;------------------------------------------------------------------
;; read 512 bytes of data from track 0, sector &C1 from disc drive 0
;; HL = address of buffer
;; (change this value to define a different buffer address)
ld hl,buffer
;; E = drive number (0 or 1)
;; (change this value to define the disc drive to read from)
ld e,0
;; D = track number
;; (change this value to define the track to read from)
ld d,0
;; C = sector id
;;
;; sector ids for DATA format disc: &C1, &C2, &C3, &C4, &C5, &C6, &C7, &C8, &C9
;; sector ids for SYSTEM/VENDOR format disc: &41, &42, &43, &44, &45, &46, &47, &48, &49
;;
;; (change this value to define the id of the sector to read from)
ld c,&c1
;; execute command
rst 3
defw bios_read_sector
ret
;;------------------------------------------------------------------
;; this is initialised when the "BIOS: READ SECTOR" RSX has been found.
.bios_read_sector
defw 0 ;; address of function
defb 0 ;; "rom select" for function
.cmd_bios_read_sector
defb 4+&80 ;; this is the "BIOS: READ SECTOR" RSX
;;------------------------------------------------------------------
.buffer
defs 512
</pre>