The Texas Instruments Compact Computer 40 is not really a calculator. It is better described as a portable computer. In fact, I wouldn't even have this unit in my collection, had I not found one for a relatively low price recently.

Or perhaps it is a calculator after all? Like true calculators, it allows you to access many typical calculator functions with a single keystroke. There was no need to type immediate mode BASIC statements, like on other portable computers.

The CC-40 is a very pleasant little unit. I am not the only one who suspects that were it not for the lack of a permanent storage device, it'd have been enormously successful. That storage device, a planned tape drive, was never released by the company (rumor has it that it was too unreliable for mass production) and in its absence, there was no way to permanently record programs or exchange programs or data with other users.

The CC-40 is programmed in a variant of Basic. Some structured programming statements (e.g., a WHILE loop) are missing but overall, it's a solid and versatile implementation of the language. True to its calculator heritage, the CC-40 provides better floating point arithmetic precision than most BASIC computers. All this is demonstrated by the following implementation of the Gamma function:

100 DATA 76.18009172947
110 DATA -86.50532032942
120 DATA 24.01409824083
130 DATA -1.23173957245
140 DATA 1.208650973866e-3
150 DATA -5.395239384953e-6
160 INPUT "X=? ";X
170 T=1
180 IF X>=0 THEN GOTO 220
190 T=T*X
200 X=X+1
210 GOTO 180
220 G=1.00000000019
230 FOR I=1 TO 6
240 READ P
250 G=G+P/(X+I)
260 NEXT
270 G=LN(SQR(2*PI)*G/X)
280 G=G-X-5.5+LN(X+5.5)*(X+.5)
290 PRINT "G(X)=";EXP(G)/T
300 PAUSE