Computer Museum news about computers, microcomputers, hobbyist, robotics, computing, Bugbooks, Computers in the Bugbook Historical Computer Museum collection, & amateur radio staion N4USA .

Wednesday, April 30, 2014

MARK 8 Vintage Computer

Bugbook
Bugbooks
Radio Electroics Magazine July 1974
Radio Electroics Magazine July 1974
Here are five MARK8 computers all very different in the construction. These MARK-8's are in our Bugbook Microcomputer collection.

The MARK 8 computers are all very unique - some made by people skilled to do a very good work and some inexperienced in building electronic devices.

You will see a real variety in the construction of the 5 MARK 8 computers in our collection.

Click on photo's to enlarge
John Titus
MARK8 Computer
MARK8 #1    This is most likely the most complete and complex use of the MARK8 cards ever. Of course I don't know for sure and would like to hear from others about there knowledge of MARK8 Computers.

I can not imagine how many hours went into building and testing this computer. It was built for a specific use with many special cards. I have been researching for information about this computer and sent an email to WA4GVT- you will see in the next photo his amateur radio call letters are on the top front of the computer. I just received this reply today 5-5-14. Hi, Guilty as charged !! BUT with one exception, we owned that machine for a lot of years but I did not personally construct it. We were in the process of building one when this fell in our lap. I will try very hard to remember who I got it from and will let you know asap. Would love to see ur Museum some day and see some of the treasures there.
Perhaps we will find out who actually built this machine.



John Titus
MARK8 Computer


The front panel looks like it is operator friendly - with numbered keys to operate the computer and not the toggle switch register on the other Mark 8 computers.  The builder must have written a lot of code for the machine including a custom BIOS operating program -- just for the front panel.




John Titus
MARK8 CPU card 8008 microprocessor


The simple wire bus that John Titus used was directed to this add on board for a real computer bus system. All the cards plugged into this bus. The card here is the 8008 CPU card.






John Titus
Bus extender card for trouble shooting


A bus extender card came with the computer to ease the trouble shooting of various boards and software.







John Titus
MARK8 Computer



The computer is self contained with some custom cards and power supply built in.







John Titus
MARK8 Computer



I would like to know what the computer was used for as it has  a lot of I/O connectors on the back side.





                  
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Original Mark 8 Computer 
MARK 8 #2
This a very good example of a all the MARK 8 cards assembled into the basic MARK 8.  To have a working computer you had to add power supply, a case, and some way to enter data into the computer and execute programs.






Original Mark 8 Computer 
 A switch register front panel ( You see this in computer #4) was the simple approach.  You could add a serial interface and with software driver and use a teletype or other serial terminal to operate the computer.

This computer is on display in our "Bugbook Historical Microcomputer Museum" in Floyd Virginia.



     
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              Click on photo's to enlarge 
John Titus
MARK8 Computer
MARK 8 #3 This is an exact copy of John Titus's computer on display in the Smithsonian Museum.
The computer was built by Roy Justus of Christiansburg, Virginia. Roy was a student in my 'Electronics for Scientist' course at Virginia Tech in about 1973. Roy called me one day in 2007 and told me about the MARK8 he had built and would like me to have it in our "Bugbook Computer Museum. I felt very privileged to have this opportunity of such a fine gift. Needless to say when I viewed the computer I was really amazed at the great detailed construction Roy had done on the project.

John Titus
MARK8 Computer

Roy did not purchase these cards from the vendor John Titus used in his 1974 Radio Electronics article. Roy made the cards himself from the layouts furnished with the construction book you could purchase for about $5 at the time the article came out in 1974.  The boards and the wiring are a first class job -- take a look up close and see he even put strain releaf shrink wrap on each connection.





John Titus
MARK8 Computer
This is a working computer with an excellent manual of about 50 pages Roy wrote just for this project.

I am very proud to have this MARK 8 computer on display in our "Bugbook Historical Microcomputer Museum. The museum is located in downtown the Village Green in downtown Floyd Virginia. Come on by and take a look-- if you can't maybe my audio tour will be a help "CLICK".       THANK YOU  Roy Justus for this wonderful contribution to the museum.

We are using QR codes in our museum with audio description for each display case. If you would like to test and see -- here is what you get by clicking on the QR code with a smart phone -- this is display case #8 with the Roy Justus computer - click on photo to enlarge while hearing the audio tour to this cabinet. "CLICK to hear test"

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John Titus
MARK8 Computer

MARK8 #4 This MARK 8 computer was built by George Overfelt in 1975.  Very nice constuction of the basic computer with power supply, front panel and serial interface built in.

This MARK 8 is on loan to the "Mid-Atlantic Retro Computing Hobbyist"  - 'MARCH'  group and is on display in their museum.

A video tour of this computer "CLICK"


John Titus
MARK8 Computer

When I received the computer in the late 80's it was still operational.







Here is a telephone conversation with George Overfelt about the MARK 8 and other computer topics 8-15-13 - Nice that George is still active at his age - We chat now and then by phone about this MARK 8 computer he built 38 years ago in 1976 - This added 8-15-13 

I think you will enjoy this conversion with George he tells his experience building the MARK8 and with other early computers.
Here is one of my first interviews 1-28-13 with George Overfelt 25 years after we acquired the MARK8 from him. Added here 8-22-13

John Titus
MARK8 Computer



George did a nice job of wiring . He was a professional electronics person.




John Titus
MARK8 Computer


You can see the power supple as it was built below the computer in the case.




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John Titus
MARK8 Computer


MARK8 #5
This MARK8 is a good example of how hobbyist were willing to try building their own computer. A minicomputer was the only alternative in 1974 and these cost thousands of dollars - most hobbyist could not make this kind of expensive purchase -- the MARK8 gave them an opportunity to build a computer for less then $1000.



John Titus
MARK8 Computer

I don't know if this computer ever worked but the builder put a lot of work into this project. It is rather crude in the packaging and the switch register on the front.







John Titus
MARK8 Computer



The rack holding the cards in fiber board and it is now starting to disintegrate. Real wood would have lasted just fine.

I have to give the builder credit for really putting a lot of work into having his own computer - I hope it worked for him.



John Titus
MARK8 memory board



Molex type connectors were used for the integrated circuit sockets and these are well known to fail often.






John Titus
MARK8 Computer


I do not know what the blue card is -- it is  not a standard MARK8 card. Looks like the builder had some skills to use this card.






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Other MARK-8 computers "CLICK"
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Terry Ritter tells his experience building a MARK8 in 1974 - It was a lot of work to get one into operating condition - interesting story.


The MARK 8 was available as a construction article in Radio Electronics July 1974.  John Titus designed this computer to satisfy his desire to have a computer of his own. This was the first time detail instructions were available to build a microcomputer using a microprocessor chip - the Intel 8008.  Several hundred sets of boards were sold however you had to gather the parts on you own to assemble the computer.  Not many were actually assembled and even less were made operational.  Perhaps less 50  exist today.  We are fortunate to have 5 in the "Bugbook Historical Microcomputer Museum" collection .

David G Larsen
These 5 MARK 8 computers are a result of many years of collecting. I remember in the mid 80's I had given away my MARK8 computers and started to look into adding one back into  the collection and over the last 26 years have  been very fortunate to gather these 5.  The 5 are an eclectic group all very different. Two are in our museum, one at MARCH and 2 still have their life in our Bugbook museum warehouse.