Southwest Specialty Products 6800 Start LDX #TEXT JSR PDATA1 JMP Contrl Text, Fcc /Hello, Fcb

		ORG $100
	START	LDX #TEXT
		JSR PDATA1
		JMP CONTRL
	TEXT	FCB $0D, $0A
		FCC /HELLO/
		FCB 4
		END
-	The accumulator and register status after using PDATA1 is as follows:
	ACC A	Changed during the operation
	ACC B	UNCHANGED
	IXR	Contains the memory location of the 04

CHANGE (E088) CHANGE is SWTBUG‘s memory examine and change function. Change

	uses a number of other SWTBUG® subroutines.
OUT4HS (E0C8)	OUT4HS is used to output a four-digit (16-bit) hexadecimal number onto the
	control terminal. The address of the most significant byte to be output should
	be loaded into the index register before calling OUT4HS. For example, to
	out-put the 16-bit hex number stored in memory locations 1000 and 1001
	whose most significant byte is in 1000 while the least significant byte is in
	1001 the following sequence should be used:
		LDX # $1000
		JSR OUT4HS
-	If location 1000 contained a hex 3C and 1001 contained a hex 0B, an ASCII,
	3C0B would be displayed on the screen when OUT4HS is called. Remember
	memory data is handled in hex but must be output as ASCII characters which
	have a different hex value than those stored in the computer’s memory. The
	registers are affected as follows:
	ACC A	Changed during the operation
	ACC B	UNCHANGED
	IXR	Incremented by two. (1002 in this example)
OUT2HS (E0CA)	OUT2HS is similar to OUT4HS, but outputs only two hex characters (one
	byte). For example, to display the byte stored at 2008 the following sequence
	would be used:	LDX # $2000
		JSR OUT2HS
-	An ASCII 6C would	be output to the control terminal if location 2001
	contained a hex 6C. The registers are affected as follows:
	ACC A	Changed during the operation
	ACC B	UNCHANGED
	IXR	Incremented by one. (1001in this example)

OUTS (E0CC) OUTS is a subroutine that outputs one space to the control terminal.

START (E0D0) START is the beginning of a sequence of steps that initialize the system during power up or reset. First, the stack pointer is set to be A042 and is stored in SP. Next, an FF is stored in location A943. This sets the interrupt mask bit in the stack so that when a G command is given the processor will not respond to interrupts until told to do so. The type of port being used (ACIA or PIA) is then determined by initializing it as a PIA and looking to see if this worked. If not, an ACIA is assumed and the proper ACIA initialization routine, AL2, is selected. The program then goes to CONTRL sequence.

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