Overview

5.1.2Interrupt Service Table (IST)

When the CPU begins processing an interrupt, it references the interrupt service table (IST). The IST is a table of fetch packets that contain code for servicing the interrupts. The IST consists of 16 consecutive fetch packets. Each interrupt service fetch packet (ISFP) contains eight instructions. A simple interrupt service routine may fit in an individual fetch packet.

The addresses and contents of the IST are shown in Figure 5−1. Because each fetch packet contains eight 32-bit instruction words (or 32 bytes), each address in the table is incremented by 32 bytes (20h) from the one adjacent to it.

Figure 5−1. Interrupt Service Table

000h

020h

040h

060h

080h

0A0h

0C0h

0E0h

100h

120h

140h

160h

180h

1A0h

1C0h

1E0h

RESET ISFP

NMI ISFP

Reserved

Reserved

INT4 ISFP

INT5 ISFP

INT6 ISFP

INT7 ISFP

INT8 ISFP

INT9 ISFP

INT10 ISFP

INT11 ISFP

INT12 ISFP

INT13 ISFP

INT14 ISFP

INT15 ISFP

Program memory

5-6

Interrupts

SPRU733

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Texas Instruments TMS320C67X/C67X+ DSP manual Interrupt Service Table IST, 1. Interrupt Service Table