RA6800ML: An M6800 Relocatable Macro Assembler
By Jack E. Hemenway
Copyright 1978


From Back of Book
-----------------


     RA6800ML: An M6800 Relocatable Macro Assembler is a two pass assembler for 
the Motorola 6800 microprocessor.  It is designed to run on a minimum system of 
16K bytes of memory, a system console (such as a Teletype terminal), a system 
monitor (for instance, the Motorola MIKBUG read only memory program or the ICOM 
Floppy Disk Operating System), and some form of mass file storage (dual 
cassette recorders or a floppy disk).

     The Assembler can produce a program listing, a sorted Symbol Table 
listing, and relocatable object code.  The object code is loaded and linked 
with other modules using the Linking Loader LINK68.  (Refer to PAPERBYTE 
publication "LINK68: An M6800 Linking Loader" for details).

     Included in this book: a complete description of the 6800 assembly 
language and its components, including outlines of the instruction and address 
formats, pseudo instructions, and macro facilities; details on interfacing and 
using the Assembler; error messages generated by the Assembler; the Assembler 
and sample IO driver source code listings; and the PAPERBYTE bar code 
representation of the Assembler's relocatable object file.



[Introduction] To Begin With...
-------------------------------

     RA6800ML, a resident Macro Assembler for the Motorola 6800 Microprocessor, 
is a two pass assembler designed to run on a minimum system of 16K bytes of 
memory, a system console such as a Teletype, a system monitor such as the 
Motorola MIKBUG Read Only Memory program or the ICOM Floppy Disk Operating 
System (FDOS), and some form of mass file storage such as dual cassette 
recorders or a floppy disk.  A system monitor other than those mentioned above 
could be used by simply changing two IO jumps in the Assembler, a jump to the 
input-a-character routine INEEE and a jump to the output-a-character routine 
OUTEEE, and by supplying functionally equivalent IO routines for the user's 
specific system.

     The Assembler can produce a program listing, a sorted Symbol Table 
listing, and relocatable object code.  The object code is loaded and linked 
with other assembled modules using the Linking Loader LINK6800.  The companion 
PAPERBYTE publication "LINK68 - Linking Loader for Motorola 6800" gives details 
on how to use the Linking Loader.

     This book is divided into four major sections.  In the section THE SOURCE 
LANGUAGE, a detailed description of the 6800 assembly language and its 
components is given.  The instruction and address type formats are outlined in 
addition to details about the pseudo instructions and macro facilities.  This 
section provides the necessary background for coding programs in the 6800's 
assembly language and understanding the operations of the Assembler.

     The section on THE ASSEMBLER describes the actual routines which make up 
the Assembler.  Each subsection presents a logical collection of routines which 
provide a particular function.  In addition to short descriptions of the 
routines, a cross reference is given showing all calling and called by 
routines.  Additional information about pointers, flags, and temporary 
variables is supplied.  Finally, detailed flowcharts of each routine are 
provided.

     The exact IO interface needed for using the Assembler naturally depends on 
the actual configuration of the user's system.  In INTERFACING AND USING THE 
ASSEMBLER sample IO routines for a tape system and floppy disk system are 
examined.  Tips are given on how to design IO routines (or modify those 
provided as examples) to fit the user's system.  Finally, information on 
loading and executing the Assembler, as well as source and object tape formats, 
are provided.

     Section five is the appendices which contain error messages generated by 
the Assembler, the Assembler and same IO driver source code listings, the bar 
code representation of the assembler's relocatable object file, an 
implementation guide for bootstrapping RA6800ML without the use of the linking 
loader LINK68, and the Assembler and IO routines in absolute formats for the 
bootstrap process.

     Finally, a detailed INDEX is included for quick reference to a variety of 
items.

     In this book is what I believe to be a complete set of documentation for 
the 6800 assembler program.  Every flowchart, every listing, every item was 
included for one purpose: to provide the user with everything needed for the 
use of modification of the Macro Assembler.

     In addition, it was my express purpose to provide everything necessary so 
that the user can easily learn what he or she needs to know about the system.  
By providing not only the 6800 assembler language description, but also a 
source code listing and detailed description of every routine of the Assembler, 
I intend to provide the user with an opportunity to learn about the nature of 
assembler design and implementation as well as simply acquiring a useful 
software tool.  It is through this kind of encouragement that I hope to advance 
the state of the art of home computing.


Table of Contents
-----------------

To Begin With

The Source Language
     Instruction Format
     Addressing Modes
     Address Type Formats
     Pseudo Instructions
     Macros
     Program Linkage

The Assembler
     Assembler Modules Overview
     Tables
     Stacks
     Utility Routines
     Listings Routines
     Mnemonic and Symbol Table Routines
     Input and Output Routines
     Pseudo Instruction Processing
     Opcode Processing Routines
     Address Processing
     Lexical Analysis Routines
     Evaluation Routine

Interfacing And Using The Assembler
     IO Interface Conventions
     Tape Driver Routines
     Disk Driver Routines
     Assembler Loading and Execution
     Loading the Object Code
     Source Tape Format
     Object Tape Format

Appendices

     Appendix A: Error Messages
     Appendix B: Capacities
     Appendix C: Notes from a User: Implementation of RA6800ML
     Appendix D: RA6800ML Assembly Language Object Code in Absolute
                 Hexadecimal Format
     Appendix E: PAPERBYTE Bar Code Representation of RA6800ML in
                 Absolute Format
     Appendix F: Input and Output Routines for RA6800ML in Absolute Format
                 With PAPERBYTE Bar Code Representation
     Appendix G: Assembly Language Source Listing of RA6800ML
     Appendix H: ASCII Text Listing of the Relocatable Format Object
                 Code for RA6800ML
     Appendix I: PAPERBYTE Bar Code Representation of Relocatable Format
                 Object Code for RA6800ML
     Appendix J: Cassette Tape IO Listing
     Appendix K: ICOM Floppy Disk IO Listing

Index