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HP Forum Archive 12

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HP31E strange behavior after [STO][ENTER]
Message #1 Posted by Vieira, Luiz C. (Brazil) on 6 May 2003, 2:55 a.m.

Hi folks, Spice people; (Norm, you're gonna like this)

first of all, I cannot say a word about what happened before calculator's maintenance because I observed the fact today, meaning May, fifth. Also, after opening, repairing, maintaining and closing some Spices for the last two months, I have no idea if the back case of this HP31E is its original one, so I cannot tell you its serial number. All I know is that this one came to my hands with a "MADE IN BRAZIL" back case, and seemed never being opened before.

This is an HP31E that has soldered IC's and it returns 

[-8,8,8,8,8,8,8,8,]
after [STO][ENTER], and that's fine for me. Anyway I decided to play with it and, just for fun, I wanted to see [ Error 3 ] and began to ReCalL available registers (Ro to R3 in this Spice). No problem: with the 
[-8,8,8,8,8,8,8,8,8,8,]
still in the screen, it would be enough to press any key to clear the display to 0.00. Still according to the manual, all memory is cleared after [STO][ENTER], meaning stack and numbered registers.

Then it comes the weird stuff: 

[RCL][0]     [ 0.1000     ]
[RCL][1]     [ 10.0000    ]
[RCL][2]     [ 100.0000   ]
[RCL][3]     [ 1,000.0000 ]
[RCL][4]     [  Error 3   ]

I was not worried because [STO][ENTER] returned the all-eight's display and that should mean the calculator is fine. So I decided to go further: 

 
[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx]        [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[RCL][0]     [ 0.1000     ]
[RCL][1]     [ 10.0000    ]
[RCL][2]     [ 100.0000   ]
[RCL][3]     [ 1,000.0000 ]

I could not believe that was happening. I insisted:

 
[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx]        [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[RCL][0]     [ 0.1000     ]
[RCL][1]     [ 10.0000    ]
[RCL][2]     [ 100.0000   ]
[RCL][3]     [ 1,000.0000 ]

How come? I tried another approach:

 
[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx]        [ 0.0000     ]
[CLx]        [ 0.0000     ]
[x<>Y]       [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[RCL][0]     [ 0.1000     ]
[RCL][1]     [ 10.0000    ]
[RCL][2]     [ 100.0000   ]
[RCL][3]     [ 1,000.0000 ]

Now the last experiment: 

 
[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx]        [ 0.0000     ]
[f][CLALL]   [ 0.0000     ]
[RCL][0]     [ 0.1000     ]
[f][CLALL]   [ 0.0000     ]
[RCL][0]     [ 0.0000     ]
[RCL][1]     [ 0.0000     ]
[RCL][2]     [ 0.0000     ]
[RCL][3]     [ 0.0000     ]
[RCL][4]     [  Error 3   ]

Recalling any of the registers after [STO][ENTER] will allow [f][CLALL] to clear all memory. It seems as if the calculator is "stuck" and does not finish [STO][ENTER] routine unless a register is recalled, even forcing [f][CLALL] not to work properly.

Another fact: I also tested another HP31E, "sandwich-type", and I got:

 
[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx]        [ 0.0000     ]
[RCL][0]     [ 0.0000     ]
[RCL][1]     [ 0.0000     ]
[RCL][2]     [ 0.0000     ]
[RCL][3]     [ 0.0000     ]
[RCL][4]     [  Error 3   ]

No matter at all, no strange behavior. This one had a "MADE IN SINGAPORE" back case.

This is just to add another (bug?) "report" to all other Spices' ones. Or to help others with the fact that Spices may have a fucntional degradation after being repaired. In this case, the calcualtor has soldered IC's and I cannot say a word about its behavior before maintenance (replacing flex for wires).

Luiz C. Vieira - Brazil

      
Re: HP31E strange behavior after [STO][ENTER]
Message #2 Posted by David Smith on 6 May 2003, 2:47 p.m.,
in response to message #1 by Vieira, Luiz C. (Brazil)

Somewhere I remember reading that you have to power the machine off and on after the self test to make sure it is ready for the real world.

            
Re: HP31E strange behavior after [STO][ENTER]
Message #3 Posted by Vieira, Luiz C. (Brazil) on 6 May 2003, 3:35 p.m.,
in response to message #2 by David Smith

Hi, David;

as it is not a continuous-memoy unit, this would indeed be a solution.

Thank you.

Luiz C. Vieira - Brazil

                  
Re: HP31E strange behavior after [STO][ENTER]
Message #4 Posted by David Smith on 6 May 2003, 5:40 p.m.,
in response to message #3 by Vieira, Luiz C. (Brazil)

I think it also applies to the continuous memory models. I think some internal registers in the CPU get loaded with non-normal values. Since the CPU is powered off in the "C" models, it gets reset when the system is powered back on.

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