HP42S

[John Mosand]

I have been able to figure out the various functions on the keyboard, except for BST and SST. Can somebody please tell me what they mean and which function they have?
Thank you...
John Mosand

[Gerson W. Barbosa]

http://thomasokken.com/free42/42s.pdf

HTH

Gerson.

[Dale Reed]

Forgive me if I missed it, but I didn't see a good description of using these keys for program editing and debugging in the 42s.pdf document. The descriptions in the comprehensive list ("move the program pointer") are a bit less than helpful for a new programmer.

On my HP-25, they work like this:

In PROG mode:

SST moves to and displays the next program step.

BST moves to and displays the previous program step.

You can use these to scroll through your program line by line for editing, just like using the up-arrow and down-arrow in a text editor. Since they are used for moving around in a program for editing (in PROG mode), you can't store them in a program. (You can't type up-arrow into a document, either, without using Character Map or some special ALT nnn code...)

In RUN mode:

When you press and hold SST (Single STep), it shows the current step of the program, and when you release it, executes that one step, then stops (with the program pointer at the next step), leaving the X stack register displayed.

When you press and hold BST (Back STep), it moves to and displays the previous step of the program, and when you release it, does not execute anything or restore anything.

These are used in RUN mode for debugging by watching your code execute one step at a time so you can compare the results of each step against what you expect.

On an HP-25, do this:

Switch to PROG. (Assume there is no program, or press (f) PRGM to clear it.)

01 (g) x**2 (shown in the display with row/column codes)

02 (g) pi

03 X

Switch to RUN. Press GTO 0 0 to return to the beginning of the program.

Key in a number. Press and hold SST -- you see the step number (01) and the keycode for (g) x**2. Release SST -- you see your number is now squared. Press and hold SST -- you see step number 02 and the keycode for (g) pi. Release SST -- you see the number pi in the display. (Your square has been pushed to y.) Press SST -- you see step number 03 and the keycode for multiply. Release SST -- you see the area of the circle whose radius you entered.

Probably way too wordy and redundant for most forum regulars, but I hope that explained it well enough for any programming newbies.

Dale

[Gerson W. Barbosa]

Quote:

---

Forgive me if I missed it, but I didn't see a good description of using these keys for program editing and debugging in the 42s.pdf document.

---

My bad! I would swear I had read "I haven't been able to figure out the various functions on the keyboard, except for BST and SST." in the original post. So I thought a link to Strapasson's manual would be better than a lengthy explanation of all complementary functions. Aging eyes here (and brains, how could I have imagined someone would not be able to figure out the meaning of 1/x, SQRT, LOG and LN, just to mention the functions in the first row? :-)
My apologies to you and John!

Gerson.

Edited: 21 July 2012, 2:17 p.m.

[aurelio]

Hi, you can see also
here

in a few words, forgive me for the roughness, these keys allow you to browse within the program's steps back and forward in program mode, to check and modify

the "SST Single Step RUN" key was introduced the first time by HP, if I'm not wrong, with the HP25 and in RUN mode allows you to execute the program one key phrase at a time just holding it down, as a debug key

cheers

Edited: 21 July 2012, 2:01 p.m.

[Les Koller]

SST = Single STep to the next line og code
BST = BackSTep to the previous line of code

For programming.