Sym — System Mode Register: Deh, Bank0 - Samsung S3F84B8 User Manual

S3F84B8_UM_REV 1.00
4.1.38 SYM — SYSTEM MODE REGISTER: DEH, BANK0
Bit Identifier
Reset Value
Read/Write
.7
.6–.5
.4–.2
.1
.0
NOTE:
1. Since an external interface is not implemented, SYM.7 must always be '0'.
2. You can select only one interrupt level at a time for fast interrupt processing.
3. Setting SYM.1 to "1" enables fast interrupt processing for the interrupt level currently selected by SYM.2-SYM.4.
4. Following a reset, you must enable global interrupt processing by executing an EI instruction (not by writing a "1" to
SYM.0).
.7 .6
0 –
R/W –
Tri-state External Interface Control Bit
0 Normal operation (disables tri-state operation).
1 Sets the external interface lines to high impedance
(enables tri-state operation).
Not used for S3F84B8.
Fast Interrupt Level Selection Bits
0 0 0 IRQ0
0 0 1 IRQ1
0 1 0 IRQ2
0 1 1 IRQ3
1 0 0 IRQ4
1 0 1 IRQ5
1 1 0 IRQ6
1 1 1 IRQ7
Fast Interrupt Enable Bit
0 Disables fast interrupt processing.
1 Enables fast interrupt processing.
Global Interrupt Enable Bit
0 Disables all interrupt processing.
1 Enables all interrupt processing.
.5 .4 .3
– x x
– R/W R/W
(1)
(2)
(3)
(4)
4-35
4 CONTROL REGISTERS
.2 .1
x 0
R/W R/W R/W
.0
0