Texas Instruments MBA

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: 10(8+2) digits
Weight: 6 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"AA" NiCd Advanced functions: Exp Lreg Fin 
External power: AC-9132 adapter (5.7VAC 240mA)   Memory functions: +/-/×/÷ 
    Programming model: Keystroke entry 
Precision: 11 digits Program functions:  
Memories: 12(8) numbers Program display: Keycode display  
Program memory: 32 program steps Program editing: Overwrite capability  
Chipset:   Forensic result:  

mba.jpg (17912 bytes)For me, this calculator represented an unexpected surprise. I knew about it of course; it's not an uncommon model. What I didn't even suspect is that it is a programmable unit. Because of this, I had no interest in acquiring one. Fortunately, my wife didn't know this, which is why one day she came home with an MBA that she purchased for the grand total of 50 cents at a local thrift store.

Programmability is not the only interesting feature of the MBA. As Palmer Hanson (whose name is well known to readers of the the one-time TI calculator enthusiast newsletter, the TI PPC Notes) noted, it is probably the only business calculator that uses precedence logic (which TI called A.O.S).

The programming model of the MBA is very similar to that of the TI-55. There are no instructions for control transfer or conditional execution (note, though, that it is possible to contrive conditional loops using self-modifying code); program memory is a mere 32 program steps, executed sequentially. However, using a technique involving the reset button and the fact that programs halt on errors, it is possible to create simple loops, including the simple factorial program presented here. Note that except for the difference in keycodes, this program is identical to the factorial program I wrote for the TI-55.

00 51	STO
01 01	1
02 32	1/x
03 61	RCL
04 01	1
05 55	×
06 51	STO
07 00	0
08 43	(
09 61	RCL
10 01	1
11 65	-
12 01	1
13 44	)
14 41	RST