Qualitron 1421 Programmable Scientific

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:   Display type: Numeric display  
New price:   Display color: Red  
    Display technology: Light-emitting diode 
Size: 5½"×3"×1½" Display size: 8 digits
Weight: 9 oz    
    Entry method: Reverse Polish Notation 
Batteries: 4×"AA" alkaline Advanced functions: Trig Exp 
External power: 6VDC   Memory functions:  
I/O:      
    Programming model: Keystroke entry 
Precision: 8 digits Program functions:  
Memories: 1 numbers Program display:  
Program memory: 102 program steps Program editing: Step delete capability  
Chipset: National Semiconductor   Forensic result: 8.843762  

q1421.jpg (20641 bytes)What an unusual little calculator this is! This calculator has apparently been sitting in its retail box for the last 25 years or so. I never even heard about this model until one day it appeared on eBay. It turns out to be a functional equivalent of the Novus Mathematician PR (4515) with the same features and limitations. It has generous program storage capacity (102 unmerged program steps) but the machine's utility is limited by the fact that it has only 1 memory register, a 3-level stack, no exponential display (!), and no control transfer or conditional execution capability.

Even so, it's a useful machine. It has a very pleasing, large, bright LED display, somewhat unusual for calculators of this era. Overall, the machine gives a pleasing, robust feel and appearance, with a good quality plastic case and snappy keyboard.

Demonstrating the calculator's programming model, the program below is yet another implementation of my favorite programming example, the Gamma function. Using a variant of Stirling's formula, this method yields 7+ digits of precision calculating the natural logarithm of the Gamma function of any positive argument.

ENTER
5
+
MS
ln
MR
×
MR
-
π 
2
×
MR
÷
ln
2
÷
+
1
2
1/x
MR
÷
+
7
2
1/x
5
÷
MR
÷
MR
÷
MR
÷
-
2
5
2
1/x
5
÷
MR
÷
MR
÷
MR
÷
MR
÷
MR
÷
+
1
M-
C
MR
1
M-
C
MR
×
1
M-
C
MR
×
1
M-
C
MR
×
1
M-
C
MR
×
ln
-