Motorola 6800 CPU Related Magazine Articles

6800 MIKBUG Dump (Interface Age)(March 1979) 6800 MIKBUG Dump
By Tom Munnecke
Source: "Interface Age"
March 1979

This 33-byte program allows the user to look at certain areas of memory at strategic times when debugging an assembler program on 6800 systems using the MIKBUG monitor.

-- 2 Pages, B&W, 35K
A Color Television Interface (Interface Age)(December 1979) A Color Television Interface: Easy - Versatile - Inexpensive
By William Rogers
Source: "Interface Age"
December 1979

First paragraph from article:

"The contents of this application note will cover many topics concerning the Video Display Generator; generalizing on some, baiting with others and specifying one complete project. First, I'll talk about why a versatile system is easy to build inexpensively. Then I'll turn to the performance abilities of the VDG and then mention two systems on either extreme. Fourth I'll enter into a software section including a demonstrating program, an expandable TV output display program (for an existing terminal) and a cursor program, which is the main software in this article, and is also expand-able. Fifth comes the hardware section complete with an operational schematic for an Exorcisor compatible board. Other systems may function with the hardware as long as the proper signals are used."

-- 11 Pages, B&W, 294K
APF Imagination Machine - A Review APF Imagination Machine - A Review
By Paul A. Stark
Source: "Kilibaud Microcomputing"
December 1980

This is an in-depth review of the APF Imagination Machine computer. The article was written by someone who purchased the machine and seemed to use it regularly. This is definitely a must-read article for those looking for details of the system.

There is a box-out called "More on APF's Graphics" written by Richard Esposito. It includes a BASIC program called "Hi Res Graphics Demonstration" that was written in December 1979 (a full year before the article was published).

-- 10 Pages, Grayscale, 6.46MB
A Text Editor for the 6800 A Text Editor for the 6800
By Robert Hudson
Source: "Interface Age"
September 1980

This small program (about 1k) is NOT a full-screen editor, it is a line editor. Here are the first two paragraphs of the article:

A text editor is an important basic tool used to prepare the many types of files for everyday computer operations. It is a software program that allows one to easily create or modify text material. The text can include programs in Basic, Fortran, PL/1, or assembler language as well as job control language, data file, or magazine articles. The following text editor should be appealing to 6800 microcomputer owners due to its small size and powerful set of commands.

The Program

The actual program requires memory from 0100 hex to 04FD hex. Also, memory is required on page zero for two buffers of 72 characters each and variable storage of 22 bytes. The variables have been arranged to facilitate the printout of the text buffer size and limits; there-fore, do not rearrange 'topbuf,' 'cpntr,' or 'endbuf.' The program is begun by executing 0100 hex (cold start). A hot start is provided by beginning execution at 0103 hex. The cold start automatically erases the text buffer. A jump table contains system links to 'mikbug' type routines (except for one). As can be seen in the listing, the command table follows the jump table. The system messages have been arranged after the command table. The actual software begins at 01AE hex. The other jump to a 'mikbug' routine is found in the 'bottom' routine where a call is made to the OUT4HS subroutine. This routine outputs a double byte word followed by a space and it increments the index register twice. The location of this call is 029E hex. The stack is initialized to A060 hex in location 01F8 hex.

-- 10 Pages, B&W, 288K
A User's View of Stringy Floppy for the 6800 A User's View of Stringy Floppy for the 6800
By Tom Mattingly
Source: "Interface Age"
February 1980

Here are the first two paragraphs from the article:

Are you unwilling to "shell out" more than $900 for a floppy disk? Don't despair because there is now an alternative: The Exatron Stringy Floppy. It is almost as fast, and just as reliable as the floppy disk. The cost is 1/2 to 1/3 less than a floppy disk.

As far as storage is concerned the stringy floppy can hold more than a cassette or single-density 5 1/4" disk. A 120-minute cassette using only one side at 30 characters per second can hold 108,000 total bytes. Only one side is used because a stringy floppy cannot be turned over. A floppy disk using the SWTPC model holds 70-86K total bytes according to my local SWTPC dealer. The stringy floppy in its longest length of 75 feet can hold 140,000 total bytes.

-- 3 Pages, Color and Grayscale, 2.59MB
Design of an M6800 Based Automatic Weigh Batch System Design of an M6800 Based Automatic Weigh Batch System
By Mike McCormick
Source: "Interface Age"
March 1980

Here are two of the three first paragraphs from the article:

The M-6800 has been successfully used as a real time process controller for automatic weigh batch systems. The weigh batchers are marketed by MCM Systems to ready mix cement producers and are rapidly gaining acceptance in other applications which require precision batching of dry material and fluids for operator selected mix designs. [...]

This article describes the design and optimization of an M-6800 based controller for the system. Following a brief review of the batching process the hardware and software design processes are reviewed.

-- 4 Pages, B&W and Grayscale, 156K
Designing the Lakeland Repeater Designing the Lakeland Repeater
By Bill Hunsicker
Source: "Interface Age"
January 1979

Here are the articles first few paragraphs along with nine goals:

     An old college friend, George P. Burdell, dropped by to see me not too long ago.
     After trading a few amenities, we began discussing computer applications.
     "Bill, I had an idea about using a microcomputer to run the Lakeland Amateur Radio Repeater."
     "I knew it! OK, I can give you some of what you want, but Just what are we setting out to accomplish? In other words, what are our goals? Here, let me show you what I mean." I then wrote 9 goals on the blackboard:


     1. Recognize input signals. (COR and others later on)
     2. Control the repeater transmitter.
     3. Keep accurate time. (transparent to current operations)
     4. Perform ID on a time scheduled basis.
     5. Maintain and update internal timers.
     6. Provide windbag, tailgate and transmitter time-out control.
     7. Provide tone-modulated code. (also transparent)
     8. Provide a "Kerchunk" filter.
     9. Provide for future growth. (Phone-Patch, etc.)

     I said, "The next thing we should do is to define the steps that need to be accomplished."
     George interrupted me. "Then we need to develop a flow chart, write the program, develop the hardware..." Our list grew to a total of eight items.

-- 6 Pages, B&W and Grayscale, 456K
High Performance Low Cost New Printer High Performance Low Cost New Printer
By Owen F. Thomas
Source: "Interface Age"
April 1979

How to interface a $257 OEM electric discharge printer to a 6800-based computer. This printer requires a special aluminum coated paper which is available for $0.95 per 90 foot roll. One roll will hold about 6,000 lines, or about 250,000 characters.

-- 13 Pages, B&W and Grayscale, 404K
Home Applications for the 6800 Home Applications for the 6800
By David E. Shambaugh
Source: "Interface Age"
June 1979

Here are the first few paragraphs from the article:

This article deals with a Motorola MEK 6800 D2 kit, which sells for about $225. The "D2" kit comes with several capabilities: an MC6800 MPU; three MCM6810 RAMs (128x8 each): two MC6820 Peripheral Interface Adapters (PIA); one Asynchronous Communication Inter-face Adapter (ACIA): one MC6871 Clock Generator and one MCM6830 ROM with JBUG monitor.

When assembled, the kit consists of these parts separated on two boards, the MPU board and the display board. The display board contains the six 7-segment displays, the keyboard and the audio cassette circuitry. This allows the ACIA and second PIA available to the user in the event that the user has access to an RS-232 TTY terminal. Wire wrap space is available for up to twenty 16-pin DIP packages for user designed circuitry.

The kit as built with the JBUG ROM, is a very powerful device which can be used for all sorts of applications around the home.

This article tells you how to take a D2 kit and make:

1) Digital Clock
2) Burglar Alarm
3) Timer/Control

-- 4 Pages, B&W and Grayscale, 677K
In-Line Machine Language Subroutines for BASIC Interpreters In-Line Machine Language Subroutines for BASIC Interpreters
By John P. Newcomer
Source: "Interface Age"
February 1979

Here are the first few paragraphs from the article:

Robert Uiterwick's Floppy ROM BASIC was an important addition to my SWTPC 6800 computer system, but I needed something more convenient than the USER function to permit machine-language operations. The need was met by what I call a PATsubroutine interpreter.

Floppy ROM BASIC doesn't care what you put after the PAT in PATCH so long as you don't overflow the input buffer. If you want to key in a sequence of machine-language instructions, you may. The trick, then, is to convert the ASCII character sequence into true machine code and execute it when the PATch command is executed by BASIC.

-- 2 Pages, B&W and Grayscale, 356K
M6800 Program Relocator M6800 Program Relocator
By Dr. Gordon W. Wolfe
Source: "Interface Age"
March 1979

Here are the first few paragraphs from the article:

One of the major advantages of a 6800-based microcomputer is the great amount of software available, either in microcomputer magazines or from the manufacturer or support companies which sell software. Basic interpreters, text editors, assemblers and disassemblers as well as several game and utility programs have all been published and are on the market as well.

One minor problem with software not written by the user is that the program may not reside in a convenient segment of RAM memory. For example, a printer handler may occupy the same memory location as the executive portion of a disassembler (obtained from a different source) requiring a handler for a printer. In order to use the handler to print the results of the disassembly, it will be necessary to have the handler in a usable location. [...]

The following program will transfer a block of data or a machine language program from one location to another and allow it to remain executable in the new location.

-- 3 Pages, B&W and Grayscale, 72K
MEK6800 D2 Evaluation Kit MEK6800 D2 Evaluation Kit
By Stanley F. Lundgren
Source: "Interface Age"
August 1980

Here are the first few paragraphs from the article:

When I decided to become familiar with microprocessors, I wanted a system that would give me experience with both hardware and software. The Motorola MEK 6800 D2 evaluation kit is such a system.

My decision to purchase the kit was mainly economic. I did not make a study of the hardware, software or bus structures. I found that for less than $300 I could have a microprocessor-driven computer system.

-- 10 Pages, B&W and Grayscale, 602K
The Motorola 6800 Instruction Set Motorola 6800 Instruction Set, The: Two Programming Points of View
By Paul M. Jessop
Source: "Byte"
January 1978

Here is the first paragraph from the article:

When faced with the problem of trying to hand assemble a machine language program, the task of looking up each of the op codes in the manufacturer's data can be quite daunting. Admittedly, some become familiar before very long but the less common instructions still cause problems (do you 6800 users remember the hexadecimal op code for TPA?). Two solutions to this dilemma are suggested here. The first is suitable for "switch flippers" and the second for users of MIKBUG and other systems with hexadecimal dump and load functions.

-- 2 Pages, Color and Grayscale, 1.13MB
Speeding up your SWTP 6800 Speeding up your SWTP 6800
By Harry Fair
Source: "Interface Age"
August 1979

Here are the first few paragraphs from the article:

The process of attempting to decrease execution time can be approached from many different angles. Some timesavers are: streamlining programs, eliminating redundancies, avoiding goto functions, decreasing the arithmetic accuracy or even go to integer arithmetic, such as in TSC's Micro BASIC. You can use a compiler instead of an interpreter for higher level languages; however, you may find the time needed for compiling and saving the compiled code outweighs the advantages on shorter programs. You can also attack the root of the problem and increase the hardware speed.

When I first began writing long statistical programs, I became painfully aware of the need for greater speed. Like all good programmers, I began to simplify and eliminate. I reduced the programs down to their very essence. I ran benchmark programs to find the fastest forms of program writing. I even declared all my variables in the start so they would be ordered in the table; but, alas, one program still took over 16 hours to run.

I began to look at other methods. A simpler form of BASIC with only integer arithmetic was out (I need the accuracy and decimals). A compiler seemed logical, but they were expensive and somewhat difficult to use. Finally there was the hardware with all those gates registers and counters.

-- 1 Page, B&W, 602K
Up_Your_Terminal (Interface Age)(Dec 1977)(Guess Your Number) Up Your Terminal, "Guess Your Number" (Excerpt Only)
By W. Fred Kennedy
Source: "Interface Age"
December 1977

This is not the complete "Up Your Terminal" article because the article is not 6800 CPU related. However, the author uses his terminal to connect to a 6800 MPU. As an aside he includes an amusing guessing game. The game doesn't have a name, so I have called it "Guess Your Number." Only a hex dump of the program is provided. The pdf includes the magazine's cover, index and the game itself.

The program is "a MIKBUG memory dump of a simple, do nothing, fun program that readers with an MP6800 MPU, a MIKBUG ROM and a little troops may find interesting."

The hex dump may be a little hard to read, so I have also included the original TIFF scan of the program, which is clearer and has no artifacting. The TIFF is .99MB and can be downloaded here:

Up_Your_Terminal (Interface Age)(Dec 1977)(Guess Your Number).tif

As with many game programs of this era, this program is extremely simple, but amusing. It seems that the programmer was having fun just relishing in the idea that the computer could "talk" back to the game player. Read the sample program run for more information.

Update: December 12, 2011:

Tom Williams worked with the "Guess Your Number" hex dump and produced some assembly code. Here are Tom's comments:

"I wrote a quick little checksums program to [verify] the S19 file was typed in correctly. - From there, it's pretty basic. -Basic assembly/disassembly. Most of the program is [ASCII,] so the remaining assembly is just access of the UART and keeping track of which guess/reply to send."

In a separate email, Tom goes on to say:

"I'll attach what I've got... I've been diddling with it over the last few hours.
- There is an emulator for the SWTPC.
- The code is calling routines that match up with "MIKBUG Engineering Note 100."

- There is a chunk of scratchpad that looks to be left over from another program, it is between the code that executes and the string constants section.

Here is Tom's disassembly of W. Fred Kennedy's program:

Here is Tom's PERL checksum script that he used to work with NumGuess: (compressed with zip)

-- 3 Pages, Color, 992K