asm-st20.txt

ST20 Assembler [C2/C4 Instructions]

ASM-ST20 by Dave2 Version
-------------------------

- ST20 Assembler (C2/C4 Instructions)
- Simple, single file source to binary image
- Creates list file for diagnostic purposes
- Win95/98/Me/NT/2K/XP

This is a first edition ST20 assembler.  It complements the complete set of C2/C4 instructions.  It is designed for small, single file source code assembly jobs.  It takes the source code, assembles, performs relative instruction reduction for minimal code size, creates a list file and a final resultant binary image file.  As a first edition is only supports a fraction of what is available in most assemblers.

Values
------

Immediate values should be hexadecimal and must be prefixed with the # symbol (standard notation with ST20).  For example:

    ldl #1  ; Load AReg with local #1


Comments
--------

Comments are started with the semicolon (;).  It is assumed that anything following the semicolon to the end of the current line is a comment.

Directives
----------

Directives indicate to the assembler specific actions or settings to be performed or taken.  There currently is only one directive, define.

Define  - the define directive allows a symbol to represent another symbol or value for use in forward instruction references.  The format is as follows:

    .define Name    Value
    
Where Name is a suitable name and Value is the value, for example:

    .define	OP_DEVSS	#100

Defines OP_DEVSS as #100.  Following this define, whenever OP_DEVSS is seen within the code, #100 is substituted.

Labels
------

Labels are used for referencing relative code locations (at current time).  A label is the first word on a line and is terminated with a colon.  Following the colon may be instructions or comments.  For example:

Start:                  ; Start of routine
        ldl	#0
	ldc	#200
	diff
	cj	Ahead
	.
	.
	.
	.
Ahead:	ldl	#5
	ldl	#4
	devsw
	j	Start


Version History
===============

Version 1.0.0 (20-Feb-2002)
    First Release