Here’s a program from a contributor, Class’67. It does high precision base conversions. In his words: Continue reading HP-67 Program – Binary View by Class’67
Category Archives: calculators
HP65 s3 – W/PRGM
The HP-65 calculator has an internal set of status flags known as the “s register”. “s3” is one of those flags but it behaves a bit strangely … Continue reading HP65 s3 – W/PRGM
HP65 s5 – Memory Full
s5 is used to record “memory full”. Here’s an example: Continue reading HP65 s5 – Memory Full
The HP65 Wait Loop
When the HP-65 calculator is sitting idle, waiting for you to get it to do something, what is it thinking? What’s going through its head? Continue reading The HP65 Wait Loop
The HP65 M Register
The M register in the HP-65 is used for a lot of very interesting things. Maybe not quite “give me the contents of the M register and I’ll show you the world”; but it is very close to that. Continue reading The HP65 M Register
The HP65 Buffer
There is a variable in the HP65 emulator named simply “buffer”. What is it? What does it do? Why is it there? Continue reading The HP65 Buffer
HP65 Flags
The HP-65 calculator has two flags and you can set, clear or test these in your programs. They allow you to remember choices or situations for later. Something happens. You use f SF 1 (or f SF 2) to remember it, and later you use f TF 1 (or f TF 2) to choose between two different courses of action.
Where are the flags stored? How does it do all that? Continue reading HP65 Flags
HP67 – h SF 4 and h CF 4
There are two unused codes in the HP-67 calculator that actually do things. These are “h SF 4” and “h CF 4”. Now, if you know the HP-67 calculator, you know it doesn’t have a “flag 4”. There are only flags 0-3 and you can set, test and clear these to your heart’s content. What’s flag 4? Continue reading HP67 – h SF 4 and h CF 4
HP67 – The Other h PI
There is an unused code for the HP-67 calculator that displays as “h PI”. (It comes up as keycode “35 73”.) It is one of the six codes that you can’t normally enter into the calculator. What does it do? Does it key in PI, like the real one? Does it do something more interesting? Continue reading HP67 – The Other h PI
HP67 – f LBL (i)
The “f LBL (i)” instruction is one of the missing codes that you can’t normally key into a HP-67 calculator. But if you do, what happens? Continue reading HP67 – f LBL (i)
HP67 Microcode – DSP 0
As you probably know, DSP n where n is one of the digit keys [0] to [9] sets the display precision. E.g. DSP 2 in FIXed mode gives you “0.00”, DSP 3 gives “0.000”.
Here’s how the internals do that Continue reading HP67 Microcode – DSP 0
HP67 Merged Keycodes – State Info
As you key in a merged keycode the calculator has to remember which keys led up to this point. After all, pressing the [0] key produces very different results if it was preceded by [f], [g], [h], [STO], [RCL], [STO] [+], and so on. Here’s how it keeps track: Continue reading HP67 Merged Keycodes – State Info
Saving Magnetic Cards
The HP-65 and HP-67 calculators have the ability to save information onto small magnetic cards. This allows you to save and reload programs so that you don’t need to key them in again each time. With the HP-67 you can also save and reload data that is in the calculator memories.
With the emulators however, Continue reading Saving Magnetic Cards
HP67 Startup code
The hp67u emulator shows a “0.00” before you get a chance to select debugging so how can you explore the HP-67’s startup code?
Continue reading HP67 Startup code
HP67 Unused Program Codes
There are six instructions you can’t enter into a HP-67 calculator.
Continue reading HP67 Unused Program Codes
HP67 Program Step 992
There were a number of strange things you could do with a HP-67 calculator when they first came out and this one stuck in my memory somehow.
As you probably know, there are only 224 program steps in the programmable part of the HP-67. Well, there were some things you could do that would get you to program step 992. Here’s the details:
Continue reading HP67 Program Step 992
HP67 GSB and RTN
With the HP67 we use LBL to name a subroutine, GSB to call one and RTN to return from one.
The question is, “how does the HP-67 know where to return to?” It needs to remember where it is up to. Where does it store that information?
Continue reading HP67 GSB and RTN
HP67 User Program Counter
The HP67 saves the user program counter in the bottom 3 nibbles (2,1,0) of ram[61]. However, you could be forgiven for thinking that those three digits don’t look anything like the program counter display. Here’s why
Continue reading HP67 User Program Counter
HP67 Internals – S 9 and 12
The HP67 internal flags S 9 and S 12 are used during keyboard data entry. The meanings for S9,S12 are: Continue reading HP67 Internals – S 9 and 12
HP67 DEG, RAD and GRD
The HP67 calculator has three angle modes: DEG, RAD and GRD.
DEG is degrees. There are 360 degrees in a circle.
RAD is radians. There are 2*PI radians (about 6.28) in a circle.
GRD is gradians. I’d never heard of these before I got my original HP67 but apparently these are used in some fields and there are 400 gradians in a circle.
Continue reading HP67 DEG, RAD and GRD
