LXVII Help

Using User-defined Keys

One of the innovations of the HP-67 is the ability to jump to a specific section of a program and start its execution with the click of a button. This allows the user to add custom functions to the calculator, and have them execute as if they are built-in functions. In effect, it allows the user to create a custom calculator that is specific to the needs of the user.

The programmable keys are on the top row of the calculator, labelled "A" to "E". The HP-67 allowed for 10 programmable functions by prefixing the keys with the "f" key.

The ability to extend the calculator, would not be very useful if the program needed to be re-entered every time the calculator was turned on, so the HP–67 had a built-in magnetic card reader similar to the ones used to read the magnetic strip on the back of credit cards. The magnetic cards could contain saved program instructions or data memory registers.

Note: Chapter 6, "Simple Programming", in the HP-67 User Manual and the HP Museum of Calculators (MohPC) have a more complete introduction to programming the HP-67 including using labels, magnetic cards and user-defined keys.

To help usaers remember what a card contained, its surface was writable, with markings that made it easy to also label the top row buttons with their programmed function. At the eight of the HP-67's popularity, Hewlett-Packard sold a number of 'Application Pacs' containing a set of pre-programmed and printed cards aimed at specific engineering and business areas.

Since the Mac doesn't have a built-in HP-67 card reader, LXVII implements it's functionality using files. To put it simply, wherever the manual specifies that a card shoud be read or written via the card reader, LXVII will present an 'Open' or 'Save' panel that allows you to specify a file that contains magnetic card data. (See 'LXVII files' to see the difference between the three types of files used by LXVII.)

LXVII also lets you customize the "A" to "E" button and "a" to "e" label legends, including a tool-tip, to help remember what the keys do when the program is loaded. Selecting the Edit->Set Key Labels... command, or (CMD-K) brings up an edit sheet that will let you specify the what information to include.

Below is the edit sheet along with information on how to use it to label your program keys.

- Select the Edit -> Set Key Labels... menu item to bring up the sheet as shown on the left.
- The left-most column shows the default labels and cannot be changed.
- The "Label" column lets you enter a abbreviation that will appear on the buttons or the background. LXVII does not limit the number of characters you can enter, but we recommend a 3 or 4 character abbreviation so it will fit properly in the label. (The magnetic cards typically used a maximum of 4 characters.)
- The "Help Info" column allows you to enter a description of what the function does. It can be any length and will appear when you hover over the button or label. The description should be a reminder for how to use that particular function. Remember that things that seem obvious about how to use the program when you write it, may seem very confusing after some weeks or months of not using it.
- The Clear button erases all labels and help info. It is for convenience for when you only need a small number of labels, and would otherwise need to delete all the other entries by hand. Be careful to clear the entries before you enter your custome information, or the button will erase them also, and the function is not undoable.
- The Defaults button resets all the label and help info fields to their default positions, as shown in the figure on the left.
- The Revert button resets all the label and help info to what they were when the edit sheet is first entered. It's meant to be used when you have made many changes to the data, and then change your mind.
- The Cancel reverts all fields to what they were when the edit sheet was first entered. It is equivalent to selecting Revert and Done.