_GetKey Codes

z80 » Intermediate

• Primary Functions
• Secondary Functions
• Alpha Functions
• Secondary-Alpha Functions

This is a quick reference for you to look up what the call _getkey returns. _Getkey waits for a keypress and stores that key press into a. It handles user input for increasing contrast and breaking programs. It is not very useful for breaking out of assembly programs because it doesn't always work. Once _getkey is done, it has changed a, de, and hl from what they were originally.

All of these keys are defined in the include file ti86asm.inc contained in includes.zip. If you include ti86asm.inc in your source file, you will be able to reference these keys by these names. This chart is really unnecessary except for a quick reference for spellings and group associations.

There are several repeated key codes, such as kLeft. It is on three of these four tables. The TI86 treats it the same for each of these cases. If you were to have the [ALPHA] key hit (so we're in the Alpha Function) and were to hit [Left], the scancode $02 would be returned by _getkey. If you were to have hit [2nd],[ALPHA] instead of [ALPHA], it would have returned $02 also. These both mean the same thing to TI-OS.

Some keys that aren't clearly defined by their equate name are as follows: kChs is [(-)] (the negate sign), kNext is [MORE], kBOL means that the user wants to go to the beginning of the line, kEOL means that the user wants to go to the end of the line, and kInv is the reciprocal key above [EE].

You can download the program keytest.asm to see which key codes are returned for which keys instead of just looking at these charts. It's easier to use the program to find the keycodes for a key which you know where it is on the keypad compared to looking it up on these tables.

When you're in a program such as Rascall, you can scroll through the programs by hitting the arrow keys one at a time, or you can hold the arrow keys down to make it scroll through the choices real fast. This is called Key Repeat. _Getkey monitors if a key is being held down and returns that keycode as soon as the routine is called instead of polling for key presses all over again. _Getkey does this by checking the status of the Key Press port (Port 1) to what it was last time _getkey was called. If it is the same, it will return the same keycode that it got before. This, however, can be disrupted when you use other ports, like to change ROM pages.

Here's an example of how to use _getkey to find out when [ENTER] was pressed. Remember that _getkey won't return to your program until a key is pressed, any key, including [ON].

key_check_loop:
	call _getkey		;wait for a keypress
	cp kEnter		;is a=kEnter
	jr z,enter_was_pressed	;it was...jump somewhere
	jr key_check_loop	;it wasn't...repeat