This week I bought an HP-42S for 20$. Today it arrived, and I noticed a low serial no. (2849A...). So I tried those speedup instructions (thank you, Gene) and it worked! That's an early x-mas gift :-)

“Use your feelings, Obi-Wan, and find him you will.”

Great news! I keep the FAST program in memory to put it into fast mode whenever I need to.

But... HP 42S fast mode is STILL a tiny percentage of the WP 34S speed.

Makes FAST mode seem like a joke! :-)

I tried Gene's procedure on my first HP-42S more than 15 years ago. But it is a ROM version C machine (3328S...), one of the later machines that Gene points out does not allow the speed change under program control. I used the other technique that Gene describes to manually change nybble 40300 from "7" to "F". (Although that description says this requires steps 1 through 7 of the initial setup, only steps 3 through 7 are required.) If the machine has reset nybble 40300 to "7" following any EXIT, the manual process with the debugger must be repeated to regain the speed increase.

I later acquired a ROM version A machine (2934S...) for which the whole process works well. It's a neat trick...I won't pretend to understand much of the "program control" version outside the basic alteration of nybble 40300.

I don't know when the ROM was altered in a manner that fails the program control process. I suspect that all ROM version A machines will work, and that all ROM version C machines will not work. I've never seen a ROM version B machine.

I really like the presence of the debugger in machines like the HP-42S, HP-17Bii, and HP-48SX. The debugger must be used just to determine the ROM version. (Press EXIT and LOG at the same time, then press the back arrow key, then press ".".) I was disappointed that the HP-48GX eliminated the debugger. Of course, the standard development library of the HP 49g+ and HP 50G is much better than any low level tools found on any other calculator.

Compare it to WP 34S SLOW mode. ;)

Well, there are 30 years between the HP-42S and the WP-34S. I'm just about to get a WP-34S, and I'm looking forward to feel its power! :-)

Edited: 16 Nov 2012, 3:47 p.m.

Viel Spaß, Jürgen! (Enjoy!)

Ist it possible to speed-up the 17bII too?

What are the requirements? The steps to undertake? How is the "right" calculator (rom) indentified?

TIA

Peter

To determine the ROM version of the HP-42S:

1.  Turn calculator ON.

2.  Press and hold ON, press LOG, then release both keys.

    [Displays the first step/screen of the self-test sequence.]

3.  Press BACKSPACE key.

    [Displays a line of hexadecimal data in two parts separated

     by a colon.  A series of memory nybble contents is shown to

     the right of the colon, while the hex address of the left-most

     nybble is shown to the left of the colon.]

4.  Press the decimal point "."

    [This tells the debugger to begin execution at the memory address

     shown to the left of the colon (from step 3 above).  The result of

     this is a display for a couple of seconds of the letter of the

     ROM version on the left side of the display.

For the HP-17Bii, in step 2 press the fourth from left "^" key at

the top of the keyboard.

The only HP-42S ROM versions I've ever seen are A and C.
The only HP-17Bii ROM version I've ever seen is B.

On the HP-42S, the nybble at 40300 sets the execution speed. The debugger is used to alter that location. Default is 7, max is F, but other values may be chosen as well to select other execution speeds, though that wouldn't be too useful. I've never tried 0 at that location.

I don't know if location 40300 does the same thing for the HP-17Bii.
One could experiment by trying step 3 to 7 that Gene listed on the web page cited in the first posting in this thread.

But whatever you try, the first time an EXIT takes place the speed resets to the default.

Has anyone tried using the spare ROM pad in the 42s & its associated command to implement a FAST command?

- Pauli

Quote:

---

The only HP-42S ROM versions I've ever seen are A and C. The only HP-17Bii ROM version I've ever seen is B.

---

I could guarantee the existence of the of the following ROM versions of production calculators (because I have the images):

• 17B English rev. A
  
• 17B International rev. BB
  
• 17BII International rev. AA
  
• 17BII International rev. BA
  
• 27S rev. A
  
• 27S rev. B
  
• 42S rev. A
  
• 42S rev. B
  
• 42S rev. C
  

Quote:

---

On the HP-42S, the nybble at 40300 sets the execution speed. The debugger is used to alter that location. Default is 7, max is F, but other values may be chosen as well to select other execution speeds, though that wouldn't be too useful. I've never tried 0 at that location.

I don't know if location 40300 does the same thing for the HP-17Bii. One could experiment by trying step 3 to 7 that Gene listed on the web page cited in the first posting in this thread.

---

All High-End Pioneers have the same CPU custom chip (Lewis) and the same memory layout. So the "Rate Control" nibble is always on location 40300 for the 17B, 17BII, 27S and 42S. But on mostly all calculator a <ON> button press will reset the "Rate Control" value to 7. So a normal exit of the debugger with <ON><SK3> will reset the "Rate Control" value also. The only way I found so far, to exit the internal debugger without pressing the <ON> key, is program execution at address 00000. Therefore goto location 00000 and press the <.> button to get a "Machine Reset".

Now I understand the reason for step 7 in this instruction.

Ciao.....Mike

BTW, the chances are high that my HP7470A simulation (to connect with your virtual HP-IL) will _not_ be ready to publish before Xmas, at least this Xmas. :(