I recently acquired an New Old Stock (NOS) Casio PB-700 with the FA-11 printer & tape recorder and an OR-4 memory module (4KB) from an eBay seller for a very cheap price. I know sometimes it’s fun to play with old technology, and this article will share some of my findings.
The PB-700 packaging is still intact ever since 1984:
And so is the printer box. The left one is the paper cover, the right one is the plastic container for the printer and accessories:
The user manuals for the two units:
Exploring the PB-700
However, when I first powered up the set, it did not work properly. The PB-700 LCD was not displaying properly (perhaps due to aging). The computer still seemed functional and responded to basic command such as BEEP.
The FA-11 did not seem to power up at all. Perhaps the rechargable battery inside the unit had died due to aging. I tried to leave it charging for 2 days and it still could not turn on. The AC adapter provided 8.5V, way beyond its specifications of 6V DC output. Some research suggests that the AC adapter is unregulated, so it may produce higher voltage when no load is applied. Whatever it was, the seller was nice enough to exchange a working set for me.
This time everything is working – the LCD is fine and the printer is able to print, although with difficulty (more on that later). The following photo shows the complete setup:
My first “Hello World” program on this device works fine, so I attempt to write a program to plot the graph of a sine wave. Luckily a sample is given in the user manual:
Take note that the line numbers must be keyed into the actual program. They are not there just for demonstration. If you don’t key in the line number, many control commands (FOR, WHILE, IF) will not work.
It took me 10 minutes to key in this program and modify it slightly to display the graph title. Here is the execution result:
If you have never worked with early computers before, you”ll be surprised at the execution speed. The following video shows you why:
It takes 20 seconds to plot the graph – you can literally see every pixels being drawn. Nowadays, modern computer can plot this graph in less than a second.
Testing the FA-11 Printer
My next try is to use a FOR loop with LPRINT to repeatedly print text to test the printer. The following video shows the printer in action:
It takes around 3 seconds to finish printing a single line of text, a slow speed thanks to the pen assembly.
There are a total of 4 pens, supporting 4 different colors. The horizontal stepper motor moves the pen assembly from left to right, a rotor will rotate the assembly to select the correct color, and a pin will push the required pen, touching the paper thus “plotting” the required text onto the screen. A very sophisticated piece of engineering! Unfortunately, this is an open-loop system – the printer does not have any ideas whether the pen assembly is correctly aligned. After a while, the pen assembly will no longer be calibrated causing the pen not to touch the paper and nothing will be printed. When this happens, I will have to stop the printing process and re-align. With care, the re-alignment can be done during printing when the pen assembly moves closer to the right.
Here is the printer output:
Because the pen slightly touches the paper when it moves from right to left during a carriage return and line feed, every line is underlined! The spacing between the lines is also not exactly equal thanks to the paper roller which doesn’t care what happens to the paper during rolling. I am not sure if this is how the quality is supposed to be. Or perhaps I have an old unit…
The output would have looked like this when the plotter was new (thanks to damaltor for posting the photo):
Tape recording & playback
My next try is to use the tape recorder to read and write programs:
This is a closer look at the cassette tape. Interestingly, the tape comes with the erase prevention tab removed (thus the REC button can’t be pressed). I have to put some paper in the holes to allow recording.
Using the SAVE command will store the current program as tones on the tape, to be retrieved later. The recorder plays the tones to be recorded during the process, making a sound similar to a dial-up modem connecting. Download the audio here.
Unfortunately, I am unable to read back the saved program using the LOAD command. The command simply hangs and I have to stop it. The recorder plays the tones of the saved program, which sound significantly different from what was recorded. Perhaps the audio head has malfunctioned due to aging, or the magnetic tape has degraded over the years and no longer suitable for recording.
Hope you will learn something new about old computer technology after reading this article. Except for having fun while testing it, the unit is not very useful to me. I have not even figured out how to insert a new line when editing a program (it’s not mentioned in the manual). Therefore, after writing this article, the unit will probably soon be put in my closet.
More technical information about the Casio PB-700 computer series and accessories is available here