Sunday, December 1, 2019

Retro Review: Tandy PC-4 Pocket Computer

Retro Review:  Tandy PC-4 Pocket Computer

Quick Facts:

Model:  Tandy PC-4
Company:  Tandy/Radio Shack
Type:  BASIC Programming Calculator
Based Off Of:  Casio PB-100, Radio Shack TRS-80 Pocket Computer PC-4
Memory: 544 bytes or 1,568 bytes with OR-1 RAM card
Years:  1982 (PB-100) - approximately 1986
Display:  One line, scrolling display, 12 character screen
Batteries:  2 CR 2032
Program Slots: 10
Other Clones: Olympia OP-544
Peripheral Devices:  12 pin expansion port for FP-12 thermal printer, FA-3 audio cassette recorder

I have the calculator from Ghostbusters.  OK, technically the Radio Shack TRS-80 Pocket Computer PC-4 (an earlier version of the Tandy PC-4).  However Tandy computers were sold through Radio Shack.  Close enough. (

Basic Programming at its Basic

The PC-4 has a simple, non-intimidating, keyboard.  All the arithmetic functions are present on the keyboard, where as the scientific functions are typed from the QWERTY keyboard.  The scientific functions available are:

ABS:  absolute value
ACS:  arc cosine
ASN:  arc sine
ATN:  arc tangent
COS:  cosine
FRAC:  fractional part
INT:  integer part
LN:  natural logarithm
LOG:  common logarithm
RAN#:  random number
RND:  round numbers  (RND(A,B) round A to 10^B precision)
SGN:  sign
SIN:  sine
SQR:  square root, note the lack of the letter "T"

The angle unit selection were selected through modes 4, 5, and 6 (degrees, radians, and grads respectively) outside of the programming environment.

You notice that the set of commands is very basic, like a basic TI-30 from the 1980s.  Statistics, factorials, polar-rectangular conversions, and the like will have to be programmed manually.  I am considering doing a series of basic programs for the PC-4 in the near future.

You can enter lower case letters and characters printed in gold (°, &, %, yen symbol ¥, etc.) by turning on EXT mode ([ S ] [ . ]).

Only two structures are available:  IF and FOR.  There are a few string commands, mainly KEY, SCR, LEN, MID (that uses a special variable $), and VAL.

The variables available are A-Z.  They can made into strings by attaching a dollar sign after the letter.

You can set which program is the current program by pressing [ S ] and any of the number keys.  For example,  [ S ] [ 0 ] makes program 0 (P0) the current program, both in editing and running.


Clearing programs are supposed to be done by the CLEAR command.  Unfortunately for me, the CLEAR command does nothing.  It could be a bug of the Tandy version PC-4.

Update:  I found about NEW, and NEW does clear the program space.  Thank you Don Shepherd!  (Discussion of the Tandy PC-4:

Thankfully, entering blank lines  (example:  10 [EXE] erases line 10) will erase lines, allowing me to clear programs one line at a time.  Also, there is a reset button on the back of the calculator that clears everything.  With the limited memory available, this would not be such a big deal.

Listing Program Lines

You can list the program lines by the LIST command, which is very helpful to review program lines.


This is a really basic, programming calculator.  I really like the PC-4 as a beginning level programming tool.   If you get the PC-4, (or TRS-80 PC-4 from Radio Shack or Casio PB-100), make sure you get it with the RAM card installed or part of the package.  There are probably many Android and iOS apps that emulate a PC-4.

The PC-4 is a pleasure to use and the keyboard is responsive.

I wonder if there will be a basic version of Python or C++ pocket computers - to get people to start learning programming languages.

Unfortunately, I still don't know the equation for determining the ionization level of spiritual appropriations.

Omegas.  "Casio PB-100"  Retrieved November 9, 2019.


All original content copyright, © 2011-2019.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

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