Samsung KS57C2308 Figure 7-1. Interrupt Execution Flowchart

KS57C2308/P2308/C2316/P2316 INTERRUPTS
7-3
Jump to interrupt start address Verify interrupt source and clear
IRQx with a BTSTZ instruction
IEx = 1 ?
Interrupt is generated. ( INT xx)
Generates the corresponding vector
interrupt and releases power down
High priority interrupt ?
IME = 1 ?
IS1,0 = 0, 0 ?
IS1,0 = 0, 1 ?
Stores the contents of PC and PSW in stack area;
set PC contents to corresponding vector address.
IS1,0 = 0,1
Retains until interrupt service
routine is completed.
IS1,0 = 1,0
NO
NO
NO
NO
YES
YES
YES
YES
YES
NO
Reset corresponding IRQx flag
Are both interrupt sources
of shared vector address used?
IRQx flag value remains 1
Jump to interrupt start address
YES
NO
Retains value until IME =1
Retains value until IEx =1
Request flag (IRQx) <-- 1
Figure 7-1. Interrupt Execution Flowchart