LINK68: An M6800 Linking Loader
By Robert D. Grappel and Jack E. Hemenway
Copyright 1978
ISBN: 0-931718-09-0


From Back of LINK68 Book
------------------------

     LINK68 is a one pass linking loader which allows separately translated 
relocatable object modules to be loaded and linked together to form a single 
executable load module.  It produces a Load Map and a load module in Motorola 
MIKBUG loader format.  The Linking Loader requires 2K 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.

     It was the express purpose of the authors of this book 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 source code and PAPERBYTE bar 
code listings, but also a detailed description of the major routines of the 
Linking Loader, they intend to provide the user with an opportunity to learn 
about the nature of linking loader design and implementation, as well as simply 
acquiring a useful software tool.


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

To Begin With

The Linking Loader

Interfacing and Using the Linking Loader

IO Interface Conventions
Tape Driver Routines
Disk Driver Routines
Execution of the Linking Loader
Input Relocatable File Format
Relocatable Input Tape Format


Appendices 	

Appendix A: Error Messages
Appendix B: Capacities
Appendix C: Notes from a User: Implementation of LINK68
Appendix D: LINK68 Assembly Language Object Code in Absolute
            Hexadecimal Format
Appendix E: PAPERBYTE Bar Code Representation of LINK68 in
            Absolute Format
Appendix F: Input and Output Routines for LINK68 in Absolute Format
            with PAPERBYTE Bar Code Representation
Appendix G: Assembly Language Source Listing of LINK68
Appendix H: ASCII Text Listing of the Relocatable Format Object Code
            for LINK68
Appendix I: PAPERBYTE Bar Code Representation of Relocatable Format Object
            Code for LINK68
Appendix J: Cassette Tape IO Listing
Appendix K: ICOM Floppy Disk IO Listing

Index 


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

     LINK68 is a one pass linking loader used to load and link object files 
produced by the Resident 6800 Macro Assembler RA6800ML (available as a 
PAPERBYTE book).  It allows separately translated relocatable object modules to 
be loaded and linked together to form a single executable load module.  LINK68 
produces a Load Map and a load module in Motorola MIKBUG loader format.

     The Linking Loader requires 2K bytes of memory, a system console such as a 
Teletype, a system monitor such as the Motorola MIKBUG read only memory program 
of the ICOM Floppy Disk Operating System (FDOS), and some form of mass file 
storage such as dual cassette recorders of a floppy disk.  A system monitor 
other than those mentioned above could be used by changing two IO jumps in the 
Linking Loader (a jump to the terminal character input routine INEEE and a jump 
to the terminal character output routine OUTEEE) and by supplying functionally 
equivalent IO routines for the user's specific system.

     This book is divided into three major sections.  THE LINKING LOADER 
provides detailed descriptions of the major routines of the Linking Loader.  
Included are details about the various routine linkages, pointers, flags, etc.  
This section provides the necessary background for using the Linking Loader as 
well as understanding its basic operations.

     INTERFACING AND USING THE LINKING LOADER gives information about the IO 
conventions used, execution of the Linking Loader, and the input file format.  
Naturally, the exact IO interface needed for using the Linking Loader depends 
on the actual configuration of the user's system.  Therefore, tips are given on 
how to design IO routines or modify those provided as examples to fit the 
user's system.  This section concludes with a discussion of the methods of 
preparing the loader for routine use in your system by reading it in and 
relocating it with a "bootstrap" version pre-linked in absolute format.

     The third section is the set of appendices which contain error messages 
generated by the Linking Loader, the Linking Loader and sample IO driver 
assembly listings, the bar code representations of the various relocatable 
object modules of the loader, and an implementation guide for bootstrapping 
LINK68 and linking loader and IO routines in absolute formats for the bootstrap 
process.

     Finally, a detailed INDEX is included for quick cross-reference to the 
Linking Loader's routines.

     In this book is what we believe to be a complete set of documentation for 
the Linking Loader.  Every flowchart, every listing, every item was included 
for one purpose: to provide the user with everything needed for the use or 
modification of the Linking Loader.

     In addition, it was the express purpose of the authors 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 source code and bar code 
listings, but also a detailed description of the major routines of the Linking 
Loader, we intend to provide the user with an opportunity to learn about the 
nature of linking loader design and implementation, as well as simply acquiring 
a useful software tool.  It is through this kind of encouragement that we hope 
to advance the state of the art of home computing.

     Robert D. Grappel
     Jack E. Hemenway