sharp pc-1001

a desktop mains scientific programmable calculator from 1973. ten digit bright vacuum tube display.

this was considerable miniaturisation for the time. a good set of scientific functions, 8 memories and 64 programmable keystrokes, but  no jumps unfortunately.

scientific function take noticeable time to compute. during this time, the display does not flicker, instead a busy light is signalled.

the busy led doubles as a program mode indicator. F PRO begins program mode and F END exits. during program mode keys pressed are recorded in sequence. H (halt) can be keyed to signal input and output. at these points the halt led is indicated.

a switch selects floating point vs. scientific notation, where an exponent is always displayed. the machine can display 10 digits plus a 2 digit exponent. the availability of an exponent was very rare at this time. not present on the fx-1 nor anita handhelds like the 841 the floating point display does not suppress trailing zeros.

example program

this key sequence implements the triangle formula c = sqrt(a^2+b^2-2*a*b*cos theta) to find the length of the side opposite sides a & b including angle theta.

x<>m 1 * HLT x<>m 2 * HLT F cos * 2 +/- = x<>m 3 mr 2 * = m+ 3 mr 1 * = + mr 3 = sqrt HLT

to execute, enter a, press S to start, enter b, press S again, enter theta and press S again. the display halts with the length c. be sure to switch to degrees if necessary. it appears that S continues the program, pressing C to clear automatically resets the program counter to the beginning.