This is a bit early but I wanted to get a few things down now Continue reading HP-29 Microcode Reference
Category Archives: calculators
HP-21 Microcode Reference
This is a summary of what I’ve found. It is likely to get updated from time to time Continue reading HP-21 Microcode Reference
HP-21 DSP
This one should be remarkably straight forward; but it isn’t. There are standard ways of doing standard things. This is a standard thing. It just doesn’t follow any of the standard ways. Here’s what happens Continue reading HP-21 DSP
HP-21 Function Key
The HP-21 has a blue function key at the top right of the keyboard. I tend to think of it as the “g” key but that’s just my background with the HP-67 which has a blue “g” key. Whatever you call it, the question is, how does it work Continue reading HP-21 Function Key
HP-21 Low Power
Here’s what the HP-21 looks like with low power:
Here’s how that happens Continue reading HP-21 Low Power
HP-21 Keypress
The HP-21 keypress routine is incredibly simple. It looks like Continue reading HP-21 Keypress
HP-21 Scan Codes
Scanning the calculator keyboard to see if a key has been pressed, works pretty much the same on a HP-21 as all the other calculators. This is the process Continue reading HP-21 Scan Codes
HP-21 Wait Loop
You’ll never see a shorter wait loop than this one. Continue reading HP-21 Wait Loop
HP-29C Flashing Dot
When I first built a microcode emulator for the HP-29C, it came up with a flashing decimal point. I didn’t remember this being the case with the real thing; but that was a long time ago and I might have forgotten.
I had a vague feeling there was something about low power and a flashing dot. Perhaps it normally flashes but doesn’t if power is low. All of the earlier (“classic”) calculators had hardware driven low power indicators, and I didn’t have any hardware in the emulator for that, so the normal behaviour must be a flashing decimal point.
My daughter said, “it makes more sense for the dot to flash during low power as the consumption would be slightly less”. That’s where all of my thinking started unraveling. Continue reading HP-29C Flashing Dot
HP-29C Error Routine
Here’s how “Error” gets displayed by the HP-29C. Continue reading HP-29C Error Routine
HP-29C Wait Loop
Calculators often sit in loops waiting for their person to do something. The HP-29C is no exception. Here’s what happens. Continue reading HP-29C Wait Loop
The New Calculator Debuggers
The Windows calculator emulators, hp29w and hp67w, come with the same advanced features as the HTML5 microcode versions did. They just work a little differently and there are some additional features. Continue reading The New Calculator Debuggers
Using the Windows Calculators
I’ve recently released two Windows-based calculator emulators: the hp29w and the hp67w:
They’re both pretty easy to use and fairly intuitive, but I do want to cover off some of the finer points. Continue reading Using the Windows Calculators
Continuous Memory Error
Hewlett-Packard produced calculators in the late 1970s which came with “Continuous Memory”. This retained programs and data in the calculator even when it was switched off. Continue reading Continuous Memory Error
HP-29 Scan Codes
A calculator keyboard gets scanned to see which, if any, key has been pressed.
It is a fairly simple process. The calculator activates each keyboard row in turn, and checks to see if a signal appears in any of the columns. Each key connects a different row to a different column. It looks like this: Continue reading HP-29 Scan Codes
HP-67 Card Reader Revisited
There are some interesting parallels between how the HP-65 card reader works and the new CRC instructions in the HP-67. There seems to be a bit more to it than we’ve heard before Continue reading HP-67 Card Reader Revisited
HP-65 Emulator Ver 1.03
There have been a couple of changes to the HP-65 Emulator and one of these may cause some confusion. Continue reading HP-65 Emulator Ver 1.03
HP-65 STD01 Day of the Week Program
This is really simple. You enter a month, day and year. Then you press the Day of the Week button and out pops a number from 0 to 6. Continue reading HP-65 STD01 Day of the Week Program
HP-65 Diagnostic Programs
The HP-65 calculator came with a “Standard Pac” of programs. That was a set of ready made solutions for some common problems. The idea was probably: if the calculator is programmable, it ought to come with some programs to show that off. It also effectively provided training material that created a whole lot of new programmers. It was a very good idea in many ways. Continue reading HP-65 Diagnostic Programs
Updated HP-65 Emulator
I’ve recently updated the HP-65 emulator. The new version says "1.02" if you choose [Menu/Display] [About].
