How do you know what revision level (or date of production) of the calculator you have? Are there any notable differences in the calculator over time? The calculator I recently obtained had an Owner's Manual Edition 7, Jan 1992, and does not appear to mention any hardware or firmware revision level differences.

From http://www.thimet.de/CalcCollection/Calculators/HP-42S/Contents.htm#ROMversion:

* Press ON & LOG together to enter the debugger.


* Press the decimal point.


* Now a character on the left and a digit on the right will be displayed briefly: This is the ROM version number.


* Press ON & the square root button together to quit the debugger.

Quote:

---

* Press ON & LOG together to enter the debugger.
* Press the decimal point.

---

It doesn't work for me:

I get three vertical lines and a beep until I press the decimal point. Then the display reads "SPD 1048352".

I can quit with ON & SQRT.

Oops, my bad. I shouldn't have just copied those instuctions from that web page.


Here's the improved version:

* Press ON & LOG together, then press left-arrow, to enter the debugger.


* Press the decimal point.


* Now a character on the left and a digit on the right will be displayed briefly: This is the ROM version number.


* Press ON & the square root button together to quit the debugger.

That's better!

Mine is C7 (serial # 3312S09630)

Hi,

only for your information:

The revision is C only.

The digit to the right is the latest warmstart event code.

Raymond

Interesting. Thanks. I have revision C. Is there any significance to that?
You (Thomas Okken) mentioned you got this key stroke sequence from a web site. Where? Are there any other odd keystrokes that can make the calculator do interesting things? In playing around I ran into some screen, RAM, ROM, URAM, and keyboard tests.

Hi,

much information can be found on:

http://www.hp42s.com/

Especially for the test mode including

the memory scanner look here:

http://www.hpcalc.org/details.php?id=1755

The latter is a page which has a link to a zip archive,

which has all needed info on the test mode,

and much more.

HTH

Raymond

I got that keystroke from http://www.thimet.de/CalcCollection/Calculators/HP-42S/Contents.htm#ROMversion, but bear in mind that that version turned out to be wrong (the "left arrow" step was missing). Still, there are some interesting tidbits there.

Another useful place to look is at Craig Finseth's site; his HP-42S page is at http://www.finseth.com/hpdata/hp42s.html.

As far as I know there are three Rom versions of the HP-42S.

- Version A with the flat display
- Version B also with the flat display bu much rarer
- Version C with the embedded display (common version)

Matthias