; This is an example of the "Hello World" program for CP/M 2.2.
; 
; http://jefftranter.blogspot.com/2014/03/using-cpm-assembler.html
;
; Converted to Z80 assembler mnemonics by Lumir Vanek
;
		.ORG 	100H			; CP/M programs start address
		JR 	START			; Go to program start
	
	;
	; Variable storage space
	;

MsgStr	 	.DB 	13, 10, "Hello world!", 13, 10, 0

Stack1		.DW 	0			; Place to save old stack
Sbot		.DS 	64			; Temp stack for us to use

	;
	; Constants
	;

STOP		.EQU 	$-1			; Top of our stack
BDOS		.EQU 	5			; Address of BDOS entry

	;
	; Start of code segment
	;

		; ------------------------------------------------------------
		; Starting sequence for CP/M programs
		
START: 
		LD HL, 0000H			; HL = 0
		ADD HL, SP			; HL = SP
		LD (Stack1), HL			; Save original stack
		LD HL, STOP			; HL = address of new stack
		LD SP, HL			; Stack pointer = our stack
	
		LD HL, MsgStr			; MsgStr  HL = address of string

LOOP1: 
		LD A, (HL)			; Read string char
		OR  A				; Set cpu flags
		JP Z, EXIT			; If char = 0 done
		LD E, A				; E = char to send
		LD C, 2				; We want BDOS func 2
		PUSH HL				; Save HL register
		CALL BDOS			; Call BDOS function
		POP HL				; Restore HL register
		INC HL				; Point to next char
		JR LOOP1			; Do next char

		; ------------------------------------------------------------
		; Finish and return to CP/M

EXIT: 
		LD HL, (Stack1)			; HL = entry stack address
		LD SP, HL			; SP = value on entry
		RET				; Return control back to CP/M

.END