ROM Routines – I/O and Misc

0013H

Inputs a byte from an input device.

001BH

Outputs a byte to an output device.

002BH

INKEY subroutine – scans keyboard. The data is not echoed on your screen. Note that calling 0358H instead will eliminate need to save DE.

0033H

DISPLAY subroutine- prints character in A at current cursor position on video display. Cursor position is stored at 4020-4021. Note that calling 033AH instead will eliminate need to save DE.

003BH

LPRINT subroutine- prints character in A on line printer. Note that calling 039CH instead will eliminate need to save DE.

0049H

INPUT subroutine- scans keyboard and waits for key to be pressed. Note that calling 0384H instead will eliminate need to save DE.

0060H

Delay loop in 14.66 microsecond increments. A value of 0 will be equal to .96 seconds.

0066H

NMI vector. Jumps here on non-maskable interrupt (ie. HALT or press of RESET button). Note- see 41BE.

0150H

SET, RESET, POINT graphics functions. You must make sure that the coordinates are within legal range.

01C9H

CLS subroutine- homes cursor and clears screen.

02B2H

SYSTEM command- prints “*?” and waits for entry. When using the SYSTEM command, if your program machine language program has an ORG for 41BEH with a 3 byte instruction following, then that 3 byte instruction will be automaticly executed after your tape is finished loading. For example:

02B2H

LINE INPUT subroutine- accepts a line of keyboard input terminated by ENTER or BREAK. Echoes characters typed and recognizes control functions (backspace, shift-backspace, etc.). None of these special characters ever get put into your buffer.

06CCH

Ref 1A19.

0A7FH

Used to pass a 06-bit value to a machine language program.

0A9AH

Used to pass a 16-bit value back to BASIC.

1A19H

Normal entry point for a READY in Level II or Disk BASIC. Note that it is better to jump to 06CCH because it does not cause an OM error on the first command that follows. On exit, HL= points to 1st character minus 1.

1BB2H

Prints “?”, inputs up to 241 characters from the keyboard and echoes characters typed. Data goes into BASIC’s input buffer. 0361H is the same as 1BB3H, less the prompt.

1D78H

(RST10H) Finds next non-blank character in a sting. It increments through string, ignoring spaces and control characters 9 and 10 (enters) and returns when the next non-blank character is encountered.

1E5AH

ASCII integer decimal to HEX converter. On Exit, DE= HEX result and HL= points to first non-decimal character.

260DH

Point to the VARPTR of a variable. If the variable doesn’t exist then create it first. On exit, DE= points to VARPTR of the variable.

28A7H

PRINT subroutine- prints a string of text on the video display, terminated by ENTER (13) or NULL (00), at current cursor position.