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: LightEmitting Diode Liion: Lithiumion rechargeable battery Lreg: Linear regression (2variable statistics) mA: Milliamperes of current Mtrx: Matrix support NiCd: NickelCadmium rechargeable battery NiMH: Nickelmetalhydrite rechargeable battery Prnt: Printer RTC: Realtime clock Sdev: Standard deviation (1variable 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 


If you look closely, you might just be able to discern a strange number on this calculator's display: 3.243F6A888. No, it's not a faulty device. Yes, that is the value of π. How come, you ask? Well, the SR22 is a very unique device: possibly the world's only electronic calculator that is designed to do integer and floating point arithmetic in three number bases, decimal, octal, and hexadecimal.
This absolutely unique device was part of Texas Instrument's first series of calculator offerings. Although not a programmable machine, it is definitely a programmer's tool, and thus it has a place in this collection. Even if its beautiful Panaplex display didn't warrant it, how could I possibly resist a calculator that can be used to compute the factorial of AA_{hex} and correctly display the result: A.55bC32206expFE?
And in case you wanted to know (I did), the value of e in hexadecimal is 2.B7E1516280C. Computing it (or indeed, the exponential of any number) is easy even on a fourbanger. The formula to use is this:
\[e^x=\frac{x^0}{0!}+\frac{x^1}{1!}+\frac{x^2}{2!}+...\]
This series converges quickly, and on an algebraic calculator with no precedence logic, it can be computed very easily. On the SR22, once you put x into memory using STO, you can then proceed with the following keystrokes:
RCL ÷ 7 + RCL ÷ 6 + RCL ÷ 5 + RCL ÷ 4 +
RCL ÷ 3 + RCL ÷ 2 + RCL ÷ 1 + RCL =
Of course for greater accuracy, you can start with a number greater than 7; to compute e to 10+ hexadecimal digits, I started with F_{hex}.