HP-35’s CHS behavior

[Matt Agajanian]

Hi all

Although I read the paragraph on the 35 page here on MoHPC, I’m having a little trouble following along the description

Could you provide me with some keystroke examples of what the paragraph is explaining? I think it would help me understand the different CHS scenarios if there were samples I could follow along.

Thanks

[AndiGer]

Don't know what exactly you mean ...
First batches of the HP35 required CHS in EEX executed before input of the exponent.
Although on the label of later batches you can enter CHS after you enter the exponent.
Is it this you are asking for?

[Matt Agajanian]

Actually, what I’m asking is this:

On the HP-35 page here on MoHPC, there is a paragraph about the CHS operation.

The explanation given there is a bit hard to follow. If I could see some examples of what the paragraph is explaining, I could understand how CHS affects the stack, and how the placement of CHS affects number entry and the stack.

In short, I’m just asking for some examples of what the paragraph is explaining.

[teenix]

(08-16-2019 08:19 PM)Matt Agajanian Wrote:  Actually, what I’m asking is this:

On the HP-35 page here on MoHPC, there is a paragraph about the CHS operation.

The explanation given there is a bit hard to follow. If I could see some examples of what the paragraph is explaining, I could understand how CHS affects the stack, and how the placement of CHS affects number entry and the stack.

In short, I’m just asking for some examples of what the paragraph is explaining.

(Lengthy reply)

HP35

Press...
3 <- starts number entry mode
3
CHS
Enter <- stops number entry mode

X = -33
Y = -33
Z = 0
T = 0

Press...
CHS
<- the user probably just wanted to change to +33

X = 33 <- which it did
Y = -33
Z = 0
T = 0

but number entry mode was stopped so CHS starts number entry mode again but the new entry will be negative

Press...
4

X = -4 <- the -4 was confusing
Y = -33
Z = 0
T = 0


Probably, the display should have been....

CHS
X = -0
Y = -33
Z = 0
T = 0

Press 4
X = -4 <- as expected
Y = -33
Z = 0
T = 0


On the later HP 67...

Press...
3
3
CHS
Enter

X = -33
Y = -33
Z = 0
T = 0

Press...
CHS

X = 33
Y = -33
Z = 0
T = 0

Press...
4

X = 4 <- this behaviour was more correct
Y = -33
Z = 0
T = 0

Back on the 35...
Continuous number entry

X = 0
Y = 0
Z = 0
T = 0

Press...
4

X = 4
Y = 0
Z = 0
T = 0

Press...
4

X = 44
Y = 0
Z = 0
T = 0

Press...
CHS

X = -44
Y = 0
Z = 0
T = 0

Press...
CHS

X = 44
Y = 0
Z = 0
T = 0

Press...
4

X = 444
Y = 0
Z = 0
T = 0

Press...
CHS

X = -444
Y = 0
Z = 0
T = 0

Press...
ENTER

X = -444
Y = -444
Z = 0
T = 0

cheers

Tony

[Matt Agajanian]

YES!!!

Thanks for the lengthy (but fully explanatory) variations. Now it makes sense!

[Thomas Okken]

(08-16-2019 09:09 PM)teenix Wrote:  On the later HP 67...

Press...
3
3
CHS
Enter

X = -33
Y = -33
Z = 0
T = 0

Press...
CHS

X = 33
Y = -33
Z = 0
T = 0

Press...
4

X = 4 <- this behaviour was more correct
Y = -33
Z = 0
T = 0

That's not quite correct. On the HP-67, CHS enables stack lift, so that final stack diagram should be

Quote:X = 4
Y = 33
Z = -33
T = 0

[teenix]

Missed that one, thanks.

Too many stack pastes :-)

cheers

Tony

[Matt Agajanian]

Thanks for taking the effort to show the way CHS works. Much appreciated!

[teenix]

(08-20-2019 04:58 PM)Matt Agajanian Wrote:  Thanks for taking the effort to show the way CHS works. Much appreciated!

Your welcome :-)

cheers

Tony

[TomC]

It would be interesting to know at what time/date/SerialNumber that this change was implemented in the HP35.

TomC