The Screen

z80 » Graphics

What you look at on the screen is called the Video Memory or sometimes the Screen Memory. It is located in the TI86 at memory address $fc00 and ends at $ffff. That's 1024 bytes for the screen.

A bit that's been set (turned to 1) in that memory area puts a little black dot in that area often called a pixel. The following chart illustrates the top left area of the screen with the proper addresses. The first byte shown has the numbers 0 through 7 representing the bit placements. Keep in mind that this is only a small slice of the whole screen.

looks like...

You can turn off and on pixels by writing to the Video Memory as in the program Screen.asm.

#include "ti86asm.inc"	;standard include file
.org _asm_exec_ram

	ld hl,$fc00	;start of video memory
	ld a,%10000000	;since screen is based on pixels/bits
			; it's best to use binary
			; representation so you
			; can picture stuff in
			; your head
	ld (hl),a	;write to video memory
	ret		;return from program

.end