;; This example shows how to access the firmware from within CP/M 2.2 and CP/M+. ;; ;; CP/M 2.2 and CP/M+ use a different address to execute firmware functions ;; but the parameters and method of calling are the same. ;; ;; Detect the version of CP/M which is in use and setup the correct firmware ;; jump. If a incorrect version of CP/M has been detected then just quit. ;; ;;--------------------------------------------------------- org &100 ;; origin for C/PM .COM programs nolist write"test3.com" .enter_firmware equ &be9b .scr_set_mode equ &bc0e .txt_output equ &bb5a .bdos equ 5 ;;--------------------------------------------------------- ;; get version of CP/M ld c,&0c ;; BDOS function get CP/M version call bdos ld a,l ;; CP/M Version cp &22 ;; CP/M 2.2? jr nz,cpmtst1 ;;----------------------------- ;; C/PM 2.2 detected ;; ;; initialise firm_jump with ;; the appropiate value ld hl,enter_firmware ld (firm_jump+1),hl jp start .cpmtst1 cp &31 ;; C/PM + (C/PM 3.1)? jr nz,cpmtst2 ;;------------------------------ ;; C/PM+ detected ;; ;; initialise firm_jump with ;; the appropiate value ld hl,(&0001) ld de,&0057 add hl,de ld (firm_jump+1),hl jp start .cpmtst2 ret ;;--------------------------------------------------------- ;; the main program .start ;;---------------------------------- ;; change the display mode to mode 1 ld a,1 call firm_jump defw scr_set_mode ;;---------------------------------- ;; display a message on the screen ld hl,test_message call display_message ;;---------------------------------- ;; quit back to command-line ret ;;--------------------------------------------------------- ;; HL = pointer to null terminated message .display_message ld a,(hl) ;; get ASCII character inc hl ;; increment pointer for next character or a ;; end of message marker (0)? ret z ;; quit if end of message marker found. call display_char ;; send character to console output jp display_message ;; loop for next char ;;--------------------------------------------------------- .display_char call firm_jump defw txt_output ;; firmware function: TXT OUTPUT ret ;;--------------------------------------------------------- ;; execute a firmware function .firm_jump jp 0 ;;--------------------------------------------------------- .test_message defb "Hello World!",0