194 IT: My 6800 Computer (194.html)

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6800 top view

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6800 bottom view

Keywords

20ma 5v0 6800 ASR33 BRA c/c++ Cole crystal Develcon DisplayPort Dodds Federal Flash FLQ Glassel Grove hangman "Hewlett Packard" HP I2C I2S IC "Infinite Loop" InfraRed Kavenaugh Lacey MacIvor ML6800L Motorola "paper tape" Python "Pulse Width Modulation" "Raspberry Pi" Regina RS232 Saskatoon SaskComp "short distance modem replacement" Sparks SPI star Teletype Thonny "University Hospital" "uSD card" USB USB-C "Wio Terminal" wire-wrap

The Motorola 6800: My First Computer Build

Around 1978, 45 years ago in Regina, Saskatchewan, I built my first home computer. As can be seen in both images above, it was a single board computer named the 6800 by Motorola Semiconductors (Source 03). The ICs on this board were wire-wrapped and socketted. It had one row of LEDs so that the current instruction could be viewed if run in single steps. It only needed 5 volts, a crystal for the clock, a few capacitors and some resistors. The "white" IC was a rom that contained some pre-written code provided by Motorola. I can still remember my elation when the first instruction worked. It was:

0   BRA    0

This "branch" instruction was the equivalent to "0: GOTO 0" in BASIC. It told the computer to fetch the next instruction from the same location as the current instruction. . . . yes, an infinite loop, the nemesis of most programmers.

I was as impressed by the Motorola company as by their 6800 computer on a chip. To every person who requested it, Motorola sent a complete library of (about 30) electronics reference books, at no charge. I still have some of those hard-cover reference books in my library. In those days, TTL logic was in its infancy and CMOS HC logic had not been heard of yet.

The "wire-wrapped" wires visible in the image on the right, were in fact, all the wiring that was necessary for this computer. I had manually wrapped every single wire. I knew that any wiring errors could be unwrapped and corrected, unlike solid traces on a more modern photographically-etched electronic circuit board. The finger-connectors on the left side of the board were not initially needed (but would be used later to connect external peripherals). Almost covering these gold-plated fingers was a narrow piece of masking tape with the names of (the row of the many additional) test points (soldered to the fingers) that enabled me to diagnose electronic issues. A smaller set of similar test points also existed along the right edge of the board. The two empty IC sockets remained empty but provided a few extra pins that served as joins between pins that needed more wire-wraps than they could "hold".

Eventually, I bought an ASR Teletype machine, so I could type programmed "source code" in ASCII keystrokes, print them out, store them on paper tape, correct them and reload them. Not one of my programs was very long. Each roll of paper tape was about 100 feet long. Each 8 bit character contained 7 bits of data plus 1 bit as an optional parity check. The characters were usually 7-bit ASCII. (I may have used the 8th bit for data, making it possible to store 1 full byte of data (or 1 character of a program "statement") per "punch" on the paper tape. These Teletypes sent and received signals at 20ma. This was before the RS232 connector interface was well-known; long before today when many USB connectors are on the scene. Today, the said-to-be poorly regulated USB-C connector is becoming more prevalent, hopefully it will become a powerful standard interface. USB-C promises much higher power delivery, speed and multiple signal types, but users just might be underwhelmed by what some USB-C implementations do NOT deliver. Only time will tell.

The next peripheral device that I made for the 6800 was magnetic tape storage using a cheap commercial audio tape recorder as is. I simply recorded the actual (two tone) audible signal of each bit to the audio tape and then played them back to reload them into the computer. (I may have used an acoustic coupler to generate/hear the audio.) This magnet tape recorder was more than 10 times faster than the teletype. The first game that I created (coded) was a version of "hangman" containing a total of perhaps 50 words that the users (my two young daughters) needed to discover. Each time a wrong letter was entered, the game added to a growing picture of a person slowly getting hanged. It might have sounded the "bell" on the teletype when the hanging person died (or perhaps when the word was successfully discovered).

The image below is an ASR33 Teletype machine that looks like the one that I used.

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ASR33 Teletype machine (with paper tape)

The actual assember language used by the 6800 is evident in the image below:

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a tiny Motorola 6800 assembler routine

The above routine (program) named "memcpy" copies a block of memory to another memory location. The character designating the beginning of a comment was a ";" in those days. Today Python uses a "#". Each memory location was 2 bytes long, the lower byte was indicated by ".L" and the higher byte by an ".H".

I am tempted to describe the wireless robot that I built in that same era, but I will leave that for another occasion.

Other Thoughts

Sources 04 and 05 might provide help using Thonny (Python) on the Raspberry Pi.

Sources 06 through 09 describe the changing USB standard. Hopefully USB-C will last many many years. On the Teletype, the first I/O interface standard was simply 20 ma or 0 ma passing through a pair of wires rented from the local 'phone company.

the first Short Distance Modem

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Our First Short Distance Modem (p97)

I was instrumental, as was David DODDS, in the creation of the first product manufactured by Develcon (shown above). It was I who suggested the need for such an invention. I also implemented the first few pairs of these "modems". The product was indeed Develcon's "short distance modem replacement". Our invention was being manufactured, on a two-by-two basis by a willing technitian, named George SPARKS before David DODDS sold him the necessary rights to create the Develcon company that soon sold hundreds of thousands of this product. Develcon and George SPARKS are both mentioned in the report in Source 10 by Robert KAVENAUGH, Ph.D. The development of the predecessor to the "short distance modem replacement" is well documented below in Book Source 01 on page 97 of the Master of Science Thesis (by myself, David KC COLE). This work was completed in November 1971 under the supervision of Blaine HOLMLUND, head of the first Department of Computer Science at the UofSask in Saskatoon. Upon completion of my M.Sc. degree, I worked for Mr. HOLMLUND as an Associate professor along with Dr. KAVENAUGH and others. Dr KAVENAUGH was one of the Department's first full-time professors under Mr. Blaine HOLMLUND. I taught the Department's first class about Operating Systems using the newly created advanced PDP-11 computers by DEC. The PDP-11 was an ideal processor for Operating Systems, perhaps a little ahead of its time. The architecture of the DEC PDP-11 was a slight improvement over the IBM 360 family of computers, but at a much lower price. I remember when David DODDS measured the long communication distance capabilities of our invention. My memory suggests that the signals went at least 14 miles through a huge spool of telephone cable loaned to him by SaskTel in Saskatoon.

The first project in my thesis was the implementation of a communications link to transmit ECGs from rural Saskatchewan towns to the University's mainframe. In the mainframe, a program from the University of St. Louis (that I installed) could automatically analyse the ECGs, providing rapid diagnoses without the immediate need for a medical doctor being near the patient. Hopefully, sick rural people could be given the correct life-saving treatments in time to make a real difference in their lives. (I worked part time as a technitian at the University Hospital, part-time as a teaching assistant and part-time as manager of the systems programmers who were responsible for the University's main 360 computer center.) But the main project in my thesis was the linking of multiple campus minicomputers to the main IBM computer in a manually switched federal (star) network. The goal was the transmission of data between departments, not necessarily for programming use. On-line computing and email had not yet been heard of by most people. The transports (modem replacements) linking the computers were designed and manufactured by David DODDS and myself. It was necessary for me to provide and install (and sometimes create) a serial telecommunications port in each of the minicomputers on campus to enable each minicomputer to communicate with the mainframe. Until my project, not one of the minicomputers was connected to another computer via a serial data line. In those days, a minicomputer cost upwards of $30,000, so there were not many on campus. Page 77 (shown below) of my thesis is the novel network (linking this federal system of computers at the University of Saskatchewan) created in 1971 by myself. My thesis is mentioned in the list of theses written by members of the COLE family. The list can be found in Web Source 11. My thesis is also listed at the website of the library of the UofSask (also at Source 11). Of course, in those days, theses were not published on-line. In my thesis, I coined the term "conversational programming" for the "real-time remote programming" that we can do today. Today, some refer to modern inter-computer communications as Remote Procedure Calls (RPC); an example of which is the automatic eRPC mechanism. Major uses are for process control systems. Today, an RPC interaction can be done automatically by computers in different locations, in the total absence of neither humans nor wires.

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My Federal System of Computers at UoS (p77)

David DODDS went on to become the head of the Department of Electrical Engineering at the UofSask. I returned to work for Alcan (this time in Montreal) under Leo LACEY and Don MacIVOR, where my systems programming & support team were developing, implementing and maintaining a "home-made" Time-Sharing System using the IBM mainframe at Alcan's head office in Montreal. This large mainframe computer provided interactive time-shared access for a total of about 60 programmers and data clerks in addition to doing much old-fashioned batch processing at Alcan. My new-found knowledge of Telecommunications was put to use by implementing a Remote Job Entry system in Arvida. This RJE system replaced the main IBM machine formerly in use at the Aluminum smelter. Because of the looming issue of the FLQ crisis in Montreal, we moved Alcan's whole head office mainframe out of the "limelight" in Place Ville Marie in downtown Montreal. Alcan did not want their computer facilities to be a "sitting target" high in Place Ville Marie for FLQ terrorists to attack. I worked with IBM to move our whole mainframe computer system to be "hidden" in Dorval. This turned Alcan's head office into a large RJE facility along with many (remote) time-sharing workstations.

Our Time-Sharing Operating System was designed, programmed and implemented by Alcan, it was the brain-child of Leo LACEY. While I was there, this system was fully operational during its on-going development. We encountered its shortcomings firsthand. (I compared this development work to repairing an automobite engine while the engine was propelling the car. This apt analogy came to mind, no doubt because Mr NANT and my father's first business venture was an automotive parts and repair business.) Mr. LACEY's Time Sharing computer system should not be confused with IBM's Time-Sharing Operating System which had a completely different provenance. Due to Quebec's FLQ crisis, I was forced to leave Quebec and rejoined Norm GLASSEL in Regina, Saskatchewan. He had become president of the provincial crown corporation named SaskComp in Regina, Sask. At SaskComp, I was hired as vice-president of Research and Telecommunications. Mr GLASSEL and his team eventually moved to Toronto, Ontario to head up a big Service Bureau owned by IBM. But I am getting ahead of myself. First, I will return to my initial employement at Alcan in the spring of 1966.

In April of 1966, my first job as an electrical engineer was to become a member of a small team of Engineers who were implementing a process control system to control the "pots" that produced aluminum in Arvida. Each pot line had about 120 5 volt electrolytic cells through which 40,000 amps passed. Yes, the IBM 1800 computer was controlling 24 Megawatts of power, no small job. Alcan operated at least 10 of these potlines in Arvida. IBM had added one of their engineers to our development team, he was there to tap into any IBM resources that were necessary for this first process control computer in the aluminum industry. There were 5 or 6 different process control projects simultaneously underway at Alcan. This was IBM's commitment to ensure the success of each project.

Back around 1968 or 1969, after completing the implementation of an IBM 1800 to do this control, I decided that I needed more computer education. I contacted the UofSask and made arrangements to enroll in the M.Sc. program. Mr. Blaine HOLMLUND, one of my former electrical engineering professors had, himself, gone to study computing in the interim. He had been named head of the Department of Computational Science in the College of Arts and Science. I would need to study some undergrad classes to "adjust" my Engineering Degree into the "equivalent" of a Bachelor of Science. At Alcan, I told my boss, Mr. Dave MORTIMER of my plans. His boss, Mr. Leo LACEY tried to convince me to stay with Alcan, but I kept to my plans. He caused Alcan to pay for my university tuition in return for my promise to consider returning to work for Alcan one day. My wife, Yvette, and I then moved to Saskatoon. I remember studying under both Dr. Kathleen BOOTH and her husband Dr. Andrew BOOTH and others. At that time, I did not know of BOTH Dr. BOOTH's previous notable work in the computer field. Dr Kathleen BOOTH taught (us) a class in computer languages. She was the thesis supervisor for Mr. Charles STOCK, a fellow student of mine. They were working on the subject of automated machine translation between French and English. Two other fellow M.Sc. students were Rick VanDenHAM and Isidore VOLK. Years later, Charles became one of my employees at Alcan in Montreal. Even later, I worked with Rick at SaskComp in Regina.

After completing my M.Sc, Mr LACEY contacted me on an irregular basis, to invite me to come and work for him at the Alcan head office in Montreal. Multiple times, I turned him down because I enjoyed the opportunities, challenges and work assignments in Saskatoon. I was working on the computerization plan for the two universities in Saskatchewan along with Dr. KAVENAUGH. It was an interesting co-incidence that I knew Dr. John COOKE outside of University because he lived next door to Carol nee NANT SMITH and her husband Fred (Smitty) SMITH in Sasktatoon in those days. Carol and Smitty became good friends of my wife and I during our time in Saskatoon. I knew Carol NANT before she married Smitty. Carol was the daughter of J. Earl NANT, the lifelong friend and business partner of my father Victor (Vic) Charles COLE. Both Carol and my wife Yvette were teachers. Carol was a great help when my wife, Yvette, was learning English in Saskatoon.

In Dr. KAVENAUGH's report, we note the dissatisfaction that he and others had with the Government of Saskatchewan, the University of Regina and SaskComp in particular. He makes little mention of the early development work done by Mr. DODDS, and myself who were contemporary employees with him at the University of Saskatchewan in the early 1970s. I was the project manager who implemented the first (16 teletype) time-sharing system at the University of Saskatchewan in Saskatoon. Dr. KAVENAUGH did make mention of this project in his report. This system that was manufactured by Hewlett Packard, was a success, being limited only by its ancient teletype machines and the meagre BASIC language. It is one of few software systems known to me, that exhibited no software bugs. . . ZERO. I shared Dr. KAVENAUGH's disapointment when the University of Saskatchewan's plans were not readily adopted by the Government. That was the very reason (the same disappointment) that caused me to leave Saskatoon and return to work for Alcan. Apparently, as his report indicates, it took many years for the University of Saskatchewan to recover from this uphill battle.

Programming Tips by Patrick

Sources 01, 04 and 05 contain some programming tips by Patrick .

Refer to Source 12 for a comparison of two RPi cameras. by Gus .

Conclusion

My little Motorola 6800 computer did not calculate any grand numerical formulas. But it taught me first hand about the inner workings of microprocessor chips.

Video Source 01 describes a tiny computer (shown below), designed in the modern era, about 45 years after the 6800. For a very low price, the Wio Terminal (described in written detail in Web Source 02) has a tiny (2 inch by 3 inch) multi-color display, 3 push-buttons, a tiny joystick, a microphone and buzzer along with WiFi, BlueTooth, a couple of leds, infraRed output (similar to TV remotes) and a light-sensor on the back, a slot that accepts a 16 GB micro-SD card, two connectors for remote peripheral Grove devices, a 3-axis accellerometer, multiple processors on-board and a serial USB interface that can connect to a keyboard/monitor (or perhaps even to an ancient ASR33 Teletype machine at 10 characters per second). BlueTooth means low-cost access to a tiny useable audio speaker such as most of us already own. The Wio Terminal even supports two of the most popular programming languages of today: Python and c/c++. An additional feature is that the Wio Terminal has a 40 pin electronic connector that functions with most Raspberry-Pi-compatible electronic devices. It also has two Analog-To-Digital Converters: something that the impressive Raspberry Pi sorely lacks. The Wio Terminal can communicate using I2C, I2S, HC logic, SPI, serial uarts and Pulse Width Modulation. I use a Raspberry Pi to communicate with the Wio Terminal via a modern USB cable. Fortunately, the Wio Terminal was designed to make use of the recently defined USB-C interface. The Wio Terminal can get its power via the USB cable, an attached Raspberry Pi or from an external rechargeable battery pack (not included). The Wio Teminal can even function as a small HDMI monitor for a Raspberry Pi, making use of the latent HDMI capability of the USB-C connector. Via USB, a file can be uploaded to the Wio Terminal's storage drive. Furthermore, the Wio Terminal's flash memory (firmware) can be "flashed" with the flick of a switch.

ALL this in one little package for around US$35 in 2023 !!

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The Tiny Wio Terminal on Display

End of Article (Sources Follow)

Sources

Book Sources

Book Source B194:01:www

An approach to a federal system of computers

by David KC COLE, B.Eng., M.Sc. Nov. 1971

Video Sources

Video Source V194:01:www

Exploring the Wio Terminal ( 1:14 min)

by Seeed Studio in 2021

Web Sources

Web Source S194:01:www

65 Linux Commands

by Patrick on 2020 E May 08
Web Source S194:02:www

Pi: Wio Terminal for Raspberry Pi (186.html)

by David Cole on 2023 D Apr 14
Web Source S194:03:www

Motorola 6800 Computer

at Wikipedia prior to 2023 E May 06
Web Source S194:04:www

Using Thonny Python on the Raspberry Pi

by Patrick on 2023 E May 06
Web Source S194:05:www

Python Cheat Sheet (for noobs)

by Patrick on 2023 E May 06
Web Source S194:06:www

How USB Ports Work

by Marshall Brain before 2023 E May 06
Web Source S194:07:www

Everything USB

by EiC: Ian Chiu before 2023 B Feb 19
Web Source S194:08:www

Everything USB

by USB-IF before 2022 J Oct 18
Web Source S194:09:www

USB Type-C (USB-C) features

by Chris Hoffman of How-To-Geek updated 2023 E May 02 or +
Web Source S194:10:www

History of Computing at UoS

by Robert N. Kavanagh, Ph.D. 2007JOct00
Web Source S194:11:www

Theses by Members of the COLE Family (40.html)

by David KC COLE 2015 B Feb 10
Web Source S194:12:www

Raspberry Pi Camera vs NoIR Camera

by Gus 2022JOct27

WebMaster: Ye Old King Cole

There is a way to "google" all the part-numbers, words and phrases in all my articles. This search limits itself ONLY to my articles. Just go to the top of "ePC Articles by Old King Cole".

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Date Written : 2023 E May 06
Last Updated : 2024 D Apr 24

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