Who has a sinclair scientific programmable?

[Chasfield]

I have just dug out my SSP and put a PP3 battery in it. So returning to the original question regarding flashing digits:

Some arithmetic operations (multiply and divide) cause a digit of the result mantissa to flash brightly for a split second as it settles. Not so with addition and subtraction. This flashing only occurs if the last operand entered had more than one digit. Repeated pressing of any arithmetic operator key against an established result causes a display digit to briefly flash.

Some slide rule functions produce similar behaviour (1/x and x^2) but square root (x) does not always do so.

No bright digit shows for Sin(x). With Cos(x), a bright zero shows at the exponent sign position while the calculator is thinking. With ArcTan(x), a bright zero shows at the leftmost display position while the calculator is thinking.

Without doubt there was no spare RAM for putting in extra code to suppress these display glitches.

I can confirm your result for 30 Sin input, and the thinking time is 20 seconds!

The serial number of my unit, printed in red on the inside of the battery cover, is 015335.

I hope this is helpful.