Apple II manual Source

studied in the first four SWEET 16 registers. Therefore, the 8 byte display starting at $0000 is large enough for this purpose.

These four registers are established as R0, R1, R2, R3:

R0	$0000	&	0001	-SWEET 16 accumulator
R1	$0002	&	0003	-Source address
R2	$0004	&	0005	-Destination address
R3	$0006	&	0007	-Number of bytes to move
.
.
.
R14	$001C	&	001D	-Prior result register
R15	$001E	&	001F	-SWEET 16 Program counter

Additionally, an examination of registers R14 and R15 will extend and understanding of SWEET 16, as fully explained in the "WOZ" text. Notice that the high order byte of R14, (located at $1D) contains $06, and is the doubled register specification (3X2=$06). R15, the SWEET 16 program counter contains the address of the next operation as it did for each step during execution of the program, which was $0312 when execution ended and the 6502 code resumed.

To try a sample run, enter the Integer Basic program as shown in Listing #1. Of course, REM statements can be omitted, and line 10 is only helpful if the machine code is to be stored on disk. Listing #2 must also be entered starting at $300.

NOTE: A 6502 disassembly does not look like listing #3, but the SOURCEROR disassembler would create a correct disassembly.

Enter "RUN" and hit RETURN

Enter "12" and hit RETURN (A$ - A$ string data)

Enter "18" and hit RETURN (high-order byte of destination)

The display should appear as follows:

$0800-C1		40	00	10	08	B1	B2	1E	(SOURCE)
$0A00-C1		40	00	10	08	B1	B2	1E	(Dest.)
$0000-1E		00	08	08	08	0A	00	00	(SWEET 16)
NOTE: The 8 bytes stored at $0A00 are identical to the 8
bytes starting at $0800, indicating									that an accurate move of 8
bytes length has			been made. They are moved one byte at a
time starting with token C1 and								ending with token 1E. If
moving less than			8 bytes,			the data			following the moved data
would be whatever existed						at	those		locations before the move.
The bytes have the following							significance:
A Token$
C1	40		00		10		08		B1	B2	1E
---------			----		--------				---------		--