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C > CASIO  > PB-100   


The PB-100 represents Casio's step towards "real" pocket computers. While its ancestor, the FX-702P, was still called "Programmable Calculator", the PB-100 proudly bears the title "Personal Computer".

However, the PB-100 seems to have been a true low-cost design. Its specifications are clearly inferior to those of its predecessor, the FX-702P, as well as to SHARP's earlier pockets. The limited 12 character display makes BASIC programming and debugging a painstaking endeavor.

In its standard version, it is equipped with 1 KB of RAM which results in only 544 bytes for BASIC, which is really limiting. At least, with the memory module OR-1, it can be upgraded to 1568 bytes of user memory, so it begins to make sense that BASIC memory can be subdivided into 10 independent program areas P0-P9.

Moreover, the keyboard had been reduced to the absolute minimum; at any rate, it provided a QWERTY style layout (the FX-702P had a non-standard alphabetical layout).
On the other hand, the cute little machine is really small and lightweight, a real pocket device.

The main circuits of the PB-100 are basically made up of two chips. Processor logics, ROM, display driver, and keyboard controller are integrated in a single CMOS VLSI chip HD61913, which has an external 4-bit bus. The second main component is a HD61914, which is a 8192-bit static RAM organized as 2048 words by 4 bits.

In 1983, the PB-100 was also released by Tandy Radio Shack as TRS-80 PC-4 and by Olympia as OP-544.

Thanks to Roman von Wartburg ( for this information.


PB-100 vs mainframe by Richard Chequer:
I have a Casio PB-100 (with the optional OR-1 memory) which I have owned and used since 1983.
I have shadowed mainframe programs (pension calculations) using the PB-100. A work colleague would code the mainframe solution and I would do the equivalent with the Casio: if the answers agreed, the mainframe code was deemed correct.
The limitations of the display do mean that you have to write any potential program out on paper prior to typing it in. I have not had many problems with the limited memory: it is not designed for running large programs.
The only limitation in the code is that there is no "ELSE" construct on IF statements. This did not limit the programming, but the coding required was less elegant and compact than if this construct was implemented.
I still use the machine today and I consider it to be much easier to use than a programmable calculator. In terms of maintenance it has only required new batteries - and not too many of those, either!

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My father bought it from Saudi Arabia (where he had a civil engineering job in 1982) for me when I was 12 years old. I learned my first programming language, BASIC, on it. Astoundingly enough, 30 years later, it is still the best calculator I''ve ever owned and I still use it. In 30 years, I''ve replaced the batteries twice or three times I think. It is truly a marvel. Who makes technology these days that''ll last 30 years?

Monday 25th April 2011
Nauman (Washington, DC)

My first computer, taught me programming when I was 8 years old. I ported lunar lander from ZX Spectrum to PB-100 when I was 9 yers old and only now I understand who unbelievably cool that was, I just wanted to play the game back then.

Now I am a CTO, this computer made the programming my lifestyle!

Saturday 4th September 2010
Jalmari Raippalinna (Finland)

My first PC, I recall two things, a blackjack game crammed in the 544 bytes.
And a regularity race among friends where the actual average speed was kept by me using the pb100 as a mere calculator.
The first leg we had 30 secs margin, and the guys with 10 secs margin taunted us. They simply lucked out after that, so we won all the other legs. $P

Monday 17th June 2019
UZsie (ITA)


NAME  PB-100
TYPE  Pocket
YEAR  1982
BUILT IN LANGUAGE  Basic interpreter
KEYBOARD  53 keys with numeric keypad
SPEED  455 kHz ceramic resonator used as system clock
RAM  1 KB (544 bytes for Basic programs) up to 2 KB
ROM  12 KB
TEXT MODES  1 line x 12 chars plus a 4 digit seven segment display part
COLORS  Monochrome LCD
SIZE / WEIGHT  165 (W) x 71 (D) x 10 (H) mm / 116 g (with batteries)
I/O PORTS  12-pin expansion port for printer and cassette interface
11-pin internal slot for memory module
POWER SUPPLY  2 x CR-2032 lithium batteries
FA-3 cassette interface
FP-12 mini thermal printer
PRICE  63 (France, Dec. 1984)

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