Interesting Computers I have owned, used, developed things for and related calculating devices

These were well before the modern laptops, dating back to the 1960's and into the 1990's

Back in the 1960's when I was in high school my computer was ANALOGUE.. a slide rule

Although I had a number of slide rules, the best and most powerful one, which saw me through university and I still have was the all metal Pickett N4-ES Vector-Type LOG-LOG dual base speed rule. 

This was a doubled sided calculator that you would flip sides with the numbers being transferred by the cursor and scale positions.

The Mechanical Calculator, The Curta

The little marvel from Liechtenstein

I bought and still have a type 1 back in the early 1970's for car rally time distant calculations.
This mechanical marvel could add, subtract, multiply and divide.  No batteries required..
One simply entered a number on the side sliders, and rotate to the top crank to add or subtract that number to the accumulator at the top (top numbers on black area).  The choice of add or subtract was controlled by pulling out or pushing in the crank.  The numbers on the top in the white area are the number of crank operations.  The top ring could be raised and rotated,  This was effect an order of magnitude change to the crank addition factor, move one position and the crank now adds 10 times the number
Still works.  Lots of info on line of how these work


As an undergrad at the University of Waterloo we were expected to make use of the vast computing power they had there.
My first method of entry, normal for students was:

Punching cards on an IBM KP-29 as shown above.  The language use was Fortran 4  (Formula Translator)  and specifically WATFOR 360 or WATFIV, the university's customized version. One card per line of code,  so sometimes the decks got rather large.  Punch your program onto to the cards,  Carry that deck over to the reader station,  the attendant would drop them in the hopper and off the file goes to the main frame.  Not long after the output is printed and you get your copy.

Just don't drop your deck of cards. 

In second year (1971) I got a job at the Computing Centre, as part of the engineering group designing and developing hardware/software to work with the computer systems the job carried on till I graduated,  Nice having an office and lab plus unlimited computing time.
Of the various projects and things developed was the WITS system  Waterloo Interactive Terminal System....  Just enter what you would have done on cards, but instead on a CRT terminal. No cards decks...

The best thing was I got to open, and put my hands IN, the IBM system 360 and 370 mainframes, (best done after hours just in case you crash the system).

The Red Room had the IBM 360/75, 360/44 and 370/145, then there was the Honeywell machine up stairs in a separate room.

The Red Room

The control panel of the IBM system 360 model 75

Now on to computers and stuff I did own or developed

1978 These two machines are my first computers. 

Both rack mounted in a DEC computer rack.

The Home Built

The one on the left side of the rack with the light silver panel and lots of switches and lights is a home built machine

I had been given a Z80 processor chip, so I obtained a few wire-wrap S-100 cards, plus a S-100 memory card and constructed a computer similar in function to the a DEC PDP11/20 as far as the panel went.  You could set the address, press load address,  and then set the data you want to write to memory at that location, press write, it would move to next location, and keep entering your program one byte at a time.

Above the machine on the open area was a small digital data tape deck and interface which I constructed to allow for loading programs.  Earlier I had it working with an audio tape deck, but digital worked far better.   Had found a nice monitor program in a Byte Magazine and modified the code to run on this machine.  Once running, the monitor software would let me use the ASCII terminal to the right, nearest the camera being an early HeathKit  terminal to command the computer.

The home built was connected via. a serial line to the machine to the right, which I lucked into buying used,  not long after I got the Z80 machine working.

The PDP-11

The right hand machine with the white and black panel in the rack is a Digital Equipment Corp (DEC) PDP-11/05N

This 16 bit machine with 4K words of CORE (8 KBytes), ran DEC RT11 operating system.
It was connected to the twin  RX01 floppy drives using 8" (256 KB)
The OS included Basic and Assembler plus a text editor

The DEC machine was connected to the DEC VT100 terminal, second one in on right.

Either computer could be connected to the Centronics dot matrix printer on top of rack

1978 IBM 2741 Printing Terminal

One early issue I had in my small engineering business was getting typed letters done.  Yes I could type, but...

So, I purchased from the University of Waterloo Computing Centre where I had worked, an IBM 2741 Terminal.  This was a modified IBM Selectric typewriter with a replaceable typeball.  As received it like most of these machines in use at the university, equipped with an APL keyboard and typeball.  APL (A Programming Language was a very powerful mathematics language).  But no problem, just get a standard office typeball, and it could use the high quality film type ribbon for top grade printout.

It was an odd duck!  The terminal used 134.5 Baud, in EBCDIC code, not ASCII.  For this machine, there was no capital or lower case character.  Instead it was as per the keyboard,  If  "abc" was sent and that would print and "abc",  send a "shift" code, and then if you sent "abc", the device would print "ABC" until you sent an un-shift code.  Exactly like the keyboard entry would be, where you press and hold shift down and type upper case characters.

I wrote some software on the DEC machine to act as a word processor, entry was done using the standard text editor used for assembler files, and I had special character strings that were printing instructions, such as new paragraph, shift or un-shift etc.  A program written in Basic parsed the text file and created the needed character sequence.  That was sent through the Z80 machine which had two serial ports, configured to input 7bit ASCII, and output it at the 134.5 Baud EBCDIC 8bit and the odd 1.5 stop bits.

Now I could write a letter,  and get a perfectly typed document.

Of course if you wanted to, you could use it as a manual typewriter.

The machine was big, the size of a large office typewriter, but was built onto a small desk that contained all the electronics.

1981 The Intertec Superbrain and a Multiwriter Printer

The Superbrain was a Z80 based machine running CP/M and had twin 5.25" floppy drives.
The computer had two Z80 processors, one for the CPU, the second acted as a disk controller.

The machine could run WordStar for word processing,  Z80/8080 assembler,  as well there was APL that would run on it.  To which we had developed a character generator for the video system to display the APL symbols.

Beside the computer was the much newer and faster word processing printer,  It was an Ahearn & Soper Multiwriter,  based on the Diablo Daisy-wheel printer, this modified unit has a number of software improvements.  And best of all, it took normal ASCII codes...
You could use it as a printer or a manual typewriter

The Little Epson MX80 printer was also connected for general printing.
The combination was a lot smaller than the z80 and PDP11 combo, so it could live next to my office, and plugged into an ordinary power outlet

1984 Compaq Portable

Wow, a portable computer, or is that a "Luggable" computer as it was know.  The size of a sewing machine, and only 28lbs.

It ran MS-DOS, had twin 5.25" floppy discs, a 8088 processor at 4.77 MHz., 128K of RAM and and would support an external monitor and printer.

1985 Corona Data System's knock off of the Compaq

A lower cost machine that like the Compaq it ran MS-DOS just like the Compaq. 


Working with BMB Compuscience we developed a patented network system call Imaginet,

It allowed file sharing between various types of machines, in the days long before the Ethernet.

BMB created a database system called the Manager, that worked on the  Commadore PET (and super PET) as well as on IBM PC's.  The network was a powerful means to allow businesses to use the same database across a number of machines.

Of course there was tBMB's video game, Sopwith in 1985 that allowed you to play against other players each on a different machine connected over the network.  Each player flew their WW1 fighter plane and attempted to shoot down the other players

screen shot of Sopwith

1988  PC Magazine give me a nice award for the All ChargeCard

This device with software allowed one to overcome some major limitations that were part of the IBM PC AT machines using a 80286 processor. 
It all had to do with a 640 KM memory limit even if a 80286 processor could address more space.  The problem was the DOS system did not know how to run programs other than in the lower part of memory.  This device allowed much more usable memory by providing memory mapping functions to allow the device to have multiple lower 640 K blocks (or smaller).  Thereby allowing each program to think it was in the bottom, but really was somewhere else.

Later Intel processors like the 80386 overcame that issue.  But, there was a lot of AT machines out there, and this simple to install device gave those machines a lot more power.

The plaque still nice on my office wall.


This likely was the first real computer that you could put in your pocket.  Battery operated as well as an AC adapter, it was fully portable and usable anywhere.

It ran MS-DOS and had a ROM based Lotus 123 spread sheet, as well as calender and other basic functions.  With the RS232 serial port one could connect it to a modem, or to another computer for file transfer.

All this in package that was about 6" x 3" and less than an inch thick. Imagine that.

I moved up to a newer model, with the model 200 which had more power and memory.  This got used until I finally bought a Palm Pilot with it's touch screen. in about 1998

I will stop here. 

Of course I have had many newer and more powerful machines, but this page was more about things from decades ago

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