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Which calculators had no known bugs?
11-18-2020, 03:31 PM
Post: #42
RE: Which calculators had no known bugs?
Ok - sure, no problem!

This is a list I compiled back in november 1981 (39 years ago ... Tongue) for our members letter for the PPC Chapter of Gothenburg, Sweden.

It contained 6 bugs collected (I guess some of them are variants of each other), but here is a raw translated list of these bugs.

Note, it's been a while, and I don't recall the numbering of the bugs (maybe different reporters of the bugs), nor can I validate since I have no HP-34C anymore to test with.
I can however reproduce most of them on my phone with the go34c application.

Bon apetit!


BUG 1:
If you in PRGM-mode press "GTO . 9 9 A" followed by a number (0-9), 'A' or 'B' this will insert a hex-code in program memory. The code is between 0xA0 and 0xAB (depending on the number/letter you entered). Similar if you press 'B' instead for the first 'A' (ie. "GTO . 9 9 B"), then you will get code between 0xB0 and 0xBB.
Reproduced on my phone.

BUG 2:
If you enter "h F? A" followed by a number (0-9), 'A' or 'B' you will enter a code between 0x20 and 0x2B. And if you replace the first 'A' with 'B' you get codes between 0x30 and 0x3B.
Reproduced on my phone, note that this is a simple way to enter the only spare instruction (0x26) in a program. See

BUG 3:
If you move the switch over to PRGM-mode and at the same time press a key that show the current program line in memory, ie. SST, R/S, GSB n or SOLVE n (but not BST), then the calculator, when you release the key, copy that line to the following line in memory.
Can't reproduce on my phone - can someone with a HP34C?

If you press "GTO . 9 9 f 9" in that order, then the keys 0-9, +, -, *, / and x<>y will not work anymore, either in RUN or PRGM-mode. You can leave this state by pressing any other key.
Reproduced on my phone.

Directly after pressing "GTO . 9 9 f 9" the keyboard will be "shifted", eg. you will get "f TAN" by pressing "f COS". This will go away as soon as any key has been pressed once. "GTO . 9 9 f 9 9" gives similar result but now "f TAN" is placed on "f 0". Other combinations of "GTO . 9 9" with 'f', 'g' or 'h' and a number 1-9 have similar effects. The number zero '0' appears different and we will issue a warning for it will sometimes start the integration instuction.
Reproduced on my phone but with a bit different result. "GTO . 9 9 f 9" result in "f SIN" by pressing "f COS". "GTO . 9 9 f 9 9" generates "->H.MS" by pressing "f COS" etc.

Enter 15 lines of instructions and press "GTO . f n" where 'n' is a number 1-9. Then the calculator jumps to line 'n+2'. If you replace the number n with the key '-', '+', '*' or '/' will give similar result, but then the calculator jumps to line 012, 013, 014 resp. 015. Even the R/S-key work in a similar way, but jumps to line 011.
Reproduced on my phone.

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RE: Which calculators had no known bugs? - ThomasF - 11-18-2020 03:31 PM

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