HP-42S rest to mfg conditions

[Rick Noyes]

Anyone out there know how to reset the HP-42s back to the as manufactured condition? I was messing about with mine and have managed to screw something up and now it doesn't think as well as it once did.

[Raymond Del Tondo]

Hi,

the normal reset is to press and hold the ON key,

then press and release the SQRT (square root) key.

This performs a so-called warmstart,

which is useful when the calc is locked for some reason.

The calc displays 'Machine reset'.

The big hammer is the 'ON-A-F' key combination,

which clears all user memory.

Press and hold the ON key,

press and hold the Sigma+ key,

press and hold the XEQ key.

Release all keys.

The calc displays 'Memory Lost' or alike.

HTH

Raymond

[Rick]

For all of you who responded to my plea. Thanks. The big hammer worked.

[Mike (Stgt)]

First try to press and hold the EXIT key and next hit the SQRT key (square root), release it and release EXIT too. This should lead to the display "Machine Reset". If that does not help try to press and hold the EXIT key, next press and hold the Sigma add key (the leftmost in the top row), and then hit the XEQ key and release all keys in inverse order. This should lead to "Memory Clear".

If this did still not help, take out the batteries over night. Or -- if you dare even with the batteries in place -- shorten the contacts for less than a 1/10th of a second.

Ciao.....Mike

BTW, I am not sure if this procedure will realy reset to NIB condition. Isn't there a counter how often you did such a reset?

[Raymond Del Tondo]

Hi,

no, there's not a counter,

but if the internal mechanics are like in the HP-48 series,

a warm start log entry will be generated.

On the HP-48, this entry indicates the reason for the last warm start.

Raymond

[HrastProgrammer]

but if the internal mechanics are like in the HP-48 series, a warm start log entry will be generated.

AFAIK, there is no warmstart log inside HP-42S (or at least I haven't found any sign of such code inside HP-42S ROM) ...

[J-F Garnier]

Hi Hrast,

I did find it, actually the wslog value is stored at #4025f, see below.
Any new emulator projects from your side?

J-F

some wslog values:

1: restart after comma mode

2: IR hardware failure? (cf hp48)

3: exec through addr 0

6 (not used on HP48 serie): invalid XROM 

7: CMOS test word corrupted



; --- HP42S version C partial disassembly listing

; J-F Garnier 2001-2002

reset:

00000 23                 P=     3                       ; wslog=3: exec through addr 0

00002 6B93               GOTO   #0039E

...

0039E 850                ST=1   0

003A1 6600               GOTO   #003A8

-----

003A5 840                ST=0   0

003A8 1BF5204            D0=(5) #4025F   ! wslog

003AF 80C0               C=P    0

003B3 15C0               DAT0=C 1        ! save wslog value

[HrastProgrammer]

I did find it, actually the wslog value is stored at #4025f, see below.

Hi Jean-Francois,

Thank you very much! I was wondering what is this #4025F nibble but never thought it could be WSLOG - I called it 'Reset Nibble' inside HP-42X which is obviously the same thing :-(

Any new emulator projects from your side?

Nothing much. I finished TI-95 emulator for Windows (you can download it from http://www.geocities.com/hrastprogrammer). HP-12/15/16C emulators are planned but I am still searching for the real machines and ROMs.

Best regards.

[Mike (Stgt)]

Hi Raymond!

Tnx 4 the clarification. Then what is the number shown on an HP-42S with the key sequence EXIT+LOG, back arrow, dot (hold)?

Ciao.....Mike

[Vieira, Luiz C. (Brazil)]

[Mike (Stgt)]

AFAIK, yes, the letter in the leftmost digit, but the number in the rightmost position?

Ciao.....Mike

[Vieira, Luiz C. (Brazil)]

Hi, Mike;

the number at the righmost position seems to be part of teh ROM version, maybe a review. I have a C 7 version and I had an A 5 as well. I don't remember having this number changed after the ROM-viewer/browser being activated.

Of course, there are others in here that now much more about this than I do, I'm writing based on what I saw myself and read here. I guess some guys like Hrast and J.F. Garnier and some others I can't remember now are the ones that will give more precise info.

Sorry not helping that much.

Cheers.

Luiz (Brazil)

Edited: 14 Oct 2004, 1:00 p.m.

[Nelson M. Sicuro (Brazil)]

I have a A 7 ROM revision HP-42S, and the number doesn't change. (This is the one that has 32K+32K SRAM ;)

Regards,

Nelson

[Nelson M. Sicuro (Brazil)]

After reading the very clear explanation from J-F Garnier, I realize my mistake on this information... I tried to reset to address 0, and it results A 3!

Best regards,

Nelson

[Mike (Stgt)]

Hi Luiz!

No need to apologize. It's not the first time J-F Garnier describes the facts, but I was too lazy to search the archives.

Ciao.....Mike

Edited: 15 Oct 2004, 6:27 a.m.

[Eric Smith]

It's the reason for the last restart. It's a one-entry log.

The ROM version is just the letter.