Casio PB-220

Datasheet legend
Ab/c: Fractions calculation
AC: Alternating current
BaseN: Number base calculations
Card: Magnetic card storage
Cmem: Continuous memory
Cond: Conditional execution
Const: Scientific constants
Cplx: Complex number arithmetic
DC: Direct current
Eqlib: Equation library
Exp: Exponential/logarithmic functions
Fin: Financial functions
Grph: Graphing capability
Hyp: Hyperbolic functions
Ind: Indirect addressing
Intg: Numerical integration
Jump: Unconditional jump (GOTO)
Lbl: Program labels
LCD: Liquid Crystal Display
LED: Light-Emitting Diode
Li-ion: Lithium-ion rechargeable battery
Lreg: Linear regression (2-variable statistics)
mA: Milliamperes of current
Mtrx: Matrix support
NiCd: Nickel-Cadmium rechargeable battery
NiMH: Nickel-metal-hydrite rechargeable battery
Prnt: Printer
RTC: Real-time clock
Sdev: Standard deviation (1-variable statistics)
Solv: Equation solver
Subr: Subroutine call capability
Symb: Symbolic computing
Tape: Magnetic tape storage
Trig: Trigonometric functions
Units: Unit conversions
VAC: Volts AC
VDC: Volts DC
Years of production: 1986  Display type: Alphanumeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 6"×7½"×½" Display size: 12 characters
Weight: 6 oz    
    Entry method: BASIC expressions 
Batteries: 2×"CR-2032" Lithium + 1×"CR-1220" Lithium Advanced functions: Trig Exp Cmem Snd 
External power:   Memory functions:  
I/O: Casio I/O     
    Programming model: BASIC 
Precision: 12 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 2(0) kilobytes Program display: Text display  
Program memory: 2 kilobytes Program editing: Text editor  
Chipset:   Forensic result: 9.00000716758  

pb220.jpg (66839 bytes)The PB-220 from Casio looks like a calculator, but it's more than that: it is a BASIC-programmable handheld computer. Its internal memory is limited but, and this is not obvious at first sight, the machine is expandable: an internal expansion slot accepts an 8 kB memory card, bringing the total up to 10 kB.

Unusual among these machines is the presence of a label card window under the display. This is similar to old, magnetic card programmable calculators like the HP-65 where a slot was provided for the card, label side up, right above the five program keys A-E. The only other Casio machine that I know of with a similar feature is the unusual PD-310 and its non-programmable counterpart, the PD-300.

An input/output port allows the PB-220 to communicate with an external printer or storage device.

The following small BASIC program demonstates the calculator's programming model by computing the Gamma function using Stirling's approximation and a simple iteration for small or negative arguments:

20 G=1
30 IF X>5 THEN 70
40 G=G*X
50 X=X+1
60 GOTO 30
70 G=X*LOGX-X+LOG(SQR(2*π/X)/G)
80 G=G+((((1/99/X/X-1/140)/X/X+1/105)/X/X-1/30)/X/X+1)/12/X