README_asm80

This is the readme for asm80.c

This is a 3 pass assembler for 8080 code. It uses
standard nmumonics as stated in the Intel MCS-85 book.

The following directives exist:

-----------------

org/ORG	- set the address at this point.

EX:

org	1000	; use address 1000 decimal
ORG	0100H	; use address 100 hex
org	A0H	; use address A0 hex
ORG	startram	; use address defined by an equ earlier

An example is:

startram	equ	0100H
org	startram	; equiv to org 0100H

-----------------


equ/EQU	 - define equates

EX:

cr	equ	0dh	; 0d hex
lf	EQU	0AH	; 0a hex
progbuf	equ	2200	; 2200 decimal 

-----------------

Note that equ/EQU and org/ORG is case insensitive
as is the hex addresses (0aH is the same as 0Ah or 0AH)

------------------

Labels - 

Labels can be any length and include leters of both cases 
and include numbers. A trailing colon (:) is not needed.

EX:

start	nop
	jmp	start

start2	mov a,m
	ret

Labels are case sensitive. START is not the same as start.

----------------

Op Codes - 

Standard Intel op codes are used.

Multi-byte opcodes have this format:

jmp	0100H	; go to address 100 hex
jmp	10	; go to address 10
jmp	start	; go to address contained in the start label
lxi h,	memstart	; note space between comma and memstart label.
			; this space (or tab) is needed.
mvi a,	10
  or 
mvi a 10

This comma/space sequence is only used for multi-byte opcodes.
Single byte opcodes have the normal form:

mov a,m
mov b,c

----------------------

The output of the assembler is 2 files: 

an output file called [file].com which is a 
direct memory dump of the assembled output
which can be used by sim80/whatever.

and a print file called [file].prn
which can be used for debugging etc.

To compile the file called  sys.asm do the following:

asm80 sys.asm

The assembler will create 2 files:
sys.prn
sys.com

-------------------------


The source code of the assembler has more info. 


Kurt Theis
<theis.kurt@gmail.com>