HP86 problem

[J-F Garnier]

(02-08-2020 05:25 AM)Alexkumt Wrote:  I thought of using the software emulator for HP87 to trace the cause of the problem through Disassembler.
...
I thought I would find help from an expert person in interpreting the disassembler part.

probably if there is some electrical noise in the hardware in that part. the problem could perhaps be traced back to them.

According to the HP86 manual, error 88 BAD STMT occurs when COM, a user function or INPUT is used in "calculator mode" (that is in immediate mode, not programming). Also when trying to enter older HP85 statements in a program.

However, playing with the emulator, typing an incorrect statement by for instance starting with a ) or ? or $ also produce the BAD STMT error.
It may be that there is a (possibly invisible) bad keystroke at the beginning of the line buffer, or the first (maybe all) characters are corrupted in an intermediate memory during the line processing.
Where is the cursor position when the error happens? It should be at the offending character, the ) or ? or $ character in my tests.

I'm afraid that attempting to trace the code in an emulator will not give you more information than that.

[Edited:]
You may try this test: type several space characters then ENDLINE. On a good system, there is no error and the blank line is just ignored.

J-F