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Michael de Estrada · (This post was last modified: 10-10-2020 03:28 AM by Michael de Estrada.)

(10-10-2020 02:55 AM)Thomas Okken Wrote:
(10-10-2020 02:07 AM)Michael de Estrada Wrote: According to Appendix A of the MATH PAC module, Flag 21 is used by the POLY program. In fact, the second line is the program after the label is SF 21, so regardless of the initial state of Flag 21, it ends up getting set by the program. The only common factor here is that the results are good when the IR Printer module is absent, and they are bad (incorrect) when the IR Printer module is present, regardless of the original state of Flag 21.

I just checked the POLY program, and it only sets flag 21, it never tests it. The only effect it can possibly have is on the AVIEW instructions on lines 256, 273, 276, 279, and 282.

VIEW and AVIEW halt program execution if flag 21 is set while flag 55 is clear; this is so that programs that want to print will give the user a chance to see their results in the display if no printer is present. I don't have an IR Printer module, but I assume that when it is present, flag 55 is set, so the behavior of the POLY program will change depending on whether the module is present or not. If you point the module at a printer, I am sure you will see the program's output appear there.

You are correct. Flag 55 is set with the IR Printer module installed and is clear with it removed. I can't check this out ATM since my IR printer is kaput (burned out printer head), but should have a replacement in about a week, and will check this out at that time.

Edit - I just hooked up my printer and indeed it does operate as you said, although it just prints blank lines now, its behavior suggests that it is printing the results without the calculator pausing for user input via the R/S key. The value in the display is in fact the last root that is left in the x register when the program stops. So further pressing of the R/S key simply produces new values that have no relationship to the true output. Since Flag 55 cannot be cleared, the only way to get output sent to the display is to remove the IR Printer module when a printer is not being used.