Sharp PC-1260/PC-1261 Instruction Manual

[robve]

The PC-1261 and PC-1262 are identical, at least in their documented features.

However, I came across two bugs in a PC-1261 that I own that were fixed in the PC-1262 firmware updates. I don't know what ROM version my PC-1261 has, but these two one-liners demonstrate the bugs:

Program A:
10 "A" INPUT "#";X : END

Program B:
20 "B" WAIT : X=X : PRINT : END

RUN program A, e.g. with DEF-A. Type a number then ENTER. The PC-1261 incorrectly indicates a syntax error on line 10.

RUN program B with DEF-B. A prompt will appear when it should not. Then press +. Type in something. The cursor will appear to hang. Typing in something may actually affect the memory and destroy the stored programs (when programs are large enough to be observed to be affected). The X=X can be any assignment. On some other Sharp PC, this allows you to set an expression that you can then continue calculating with since it is in the hidden "answer" register. Same as PRINT with an expression that puts the numeric expression in the "answer" register when WAIT is used.

When you define an ESP formula in PRO mode:
#SQ=X*X
and then run program A in RUN mode, you can type SQ after the #. Then ENTER will bring up the formula. A nice hack, but that's not supposed to happen. It explains why a number is a syntax error (in ESP syntax after the #).

The fix for program A is to use INPUT "#",X with a comma to remove the # prompt when you type a number or when you press ENTER.

The fix for program B is to use PRINT "" with quotes, which does not trigger the bug.

- Rob