
Sharp PC-1403

The Sharp PC-1403 was a small scientific calculator and pocket computer manufactured by Sharp. It was the successor of the Sharp PC-1401, and had better display, more RAM and better system software.
Technical specifications.
Manufacturing started in 1986.
It is possible to convert the 1403 to a 1403H by removing the 8 K RAM and soldering in a 32 K RAM. An inverter IC is needed for this, too.
Calculator.
Calculations could be performed in two modes "CAL" and "RUN". In the former, the PC-1403 would behave like a normal scientific calculator at the time with formulas entered in algebraic logic. In "RUN" mode, BASIC statements could be entered for immediate execution and print out. The latter was similar to the Direct algebraic logic employed by modern calculators.
Programming.
The programming model employed was unstructured BASIC for which the PC-1403 distinguished between "RUN" and "PRO" mode. The later being used to enter and edit program and the former being used to execute them. 
Programming example.
Here is a sample program that computes the factorial of an integer number from 2 to 69. It can be called by pressing codice_1 codice_2 in run mode. The program is 66 bytes long.
10 "F" "allows to start the program with DEF F
20 INPUT "N=?";N "Ask for n
30 LET F=1 "Set start value of F to 1
40 FOR I=1 TO N STEP 1 "counts I from 1 to N
50 LET F=F*I "calculates F=F*I
60 NEXT I "repeats loop from line 40
70 PRINT USING "##";N;"!="; USING ;F "print result - i.E. 5!=120
80 END "end of program
Machine language programming.
It is possible to write machine language programs into memory using the POKE command and starting them with the CALL command.