45111 Datasheet, PDF (156/184 Pages) List of Unclassifed Manufacturers – 14-DAY MONEY BACK GUARANTEE

15 Appendix E: SX Data Sheet
Special function and general-purpose register addresses $00 - $0F are ‘global’ in that they can always be
accessed regardless of the contents of the FSR. Special function register $07 (RC) is available as general
purpose RAM in 20-pin SX packages. Special function registers $08 (RD) and $09 (RE) are available as
general-purpose RAM in 20 and 28-pin SX packages.
15.2.10 Direct Addressing
Global registers can be directly accessed at any time but general-purpose registers can only be directly
accessed within the current bank. The global registers are numbered $01 through $0F. Figure 25 –
Global Register Addressing SX 20/28/48/52 (direct) shows how the Global Registers are addressed in
the SX20/28 and the SX48/52. Simply specify the desired global register address in the fr operand (the
register address operand) of instructions as shown below:
mov
$0F, #$55 ; move $55 to global register $0F
Figure 25 - Global Register Addressing SX20/28/48/52 (direct)
$01 - $0F
fr (5-bit address in instruction)
4
3
2
1
0
Register Selection Bits
$00-
$01-
$02-
Global
IND
RTCC
PC
$10-
$11-
$12-
Bank 0
$0
$1
$2
Bank 1
$0
$1
$2
—
Bank 2
$0
$1
$2
—
$0F- $0F
$1F- $F
$F
$F
*n is 7 on the SX20/28. n is 15 on the SX48/52
Bank n*
$0
———
$1
$2
$F
Page 156 • SX-Key/Blitz Development System Manual 2.0 • Parallax, Inc.