8XC196MC, MD, MH USER’S MANUAL

Table 5-2. Interrupt and PTS Control and Status Registers (Continued)

Mnemonic

Address

Description

 

 

 

PI_PEND

1FBEH

Peripheral Interrupt Pending

 

 

Any bit set indicates a pending interrupt request.

 

 

 

PSW

No direct access

Processor Status Word

 

 

This register contains one bit that globally enables or disables

 

 

servicing of all maskable interrupts and another that enables or

 

 

disables the PTS. These bits are set or cleared by executing the

 

 

enable interrupts (EI), disable interrupts (DI), enable PTS (EPTS),

 

 

and disable PTS (DPTS) instructions.

 

 

 

PTSSEL

0004H, 0005H

PTS Select Register

 

 

This register selects either a PTS routine or a standard interrupt

 

 

service routine for each of the maskable interrupt requests.

 

 

 

PTSSRV

0006H, 0007H

PTS Service Register

 

 

The bits in this register are set by hardware to request an end-of-

 

 

PTS interrupt.

 

 

 

5.3INTERRUPT SOURCES AND PRIORITIES

Table 5-3 lists the interrupts sources, their default priorities (30 is highest and 0 is lowest), and their vector addresses. The unimplemented opcode and software trap interrupts are not priori- tized; they go directly to the interrupt controller for servicing. The priority encoder determines the priority of all other pending interrupt requests. NMI has the highest priority of all prioritized interrupts, PTS interrupts have the next highest priority, and standard interrupts have the lowest. The priority encoder selects the highest priority pending request and the interrupt controller se- lects the corresponding vector location in special-purpose memory. This vector contains the start- ing (base) address of the corresponding PTS control block (PTSCB) or interrupt service routine. PTSCBs must be located on a quad-word boundary in the internal register file.

5-4

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Intel 8XC196MH, 8XC196MD, 8XC196MC manual Interrupt Sources and Priorities, Pipend 1FBEH, Ptssel, Ptssrv