CHAPTER 5: OPERATION AND FUNCTION OF S5U1C63000H2

5.6 Target Interrupt and Break

When an interrupt in the target program and a break are simultaneously occurred, the target interrupt is prioritized. The break occurs after completing the stack operation of the interrupt. The program counter at the break shows the top address of the interrupt handler routine. When the target program is restarted, it executes from the top address of the interrupt handler routine.

It is the same when "I (interrupt flag) = 1" is set as the break condition by the BR command. The break occurs when the I flag goes 1. However if an interrupt occurs simultaneously, the contents of the flags after the break is displayed as "EICZ:0000" (the I flag is reset) because of the prioritized interrupt process.

5.7 Trace Function

In the execution of the emulation mode, information of the S1C63000 CPU (PC, instruction code, data RAM address, data content and CPU register value) is stored into the trace memory at every CPU bus cycle. The trace memory has a capacity of 8,192 cycles, which can store the latest instructions up to 4,096 in 2 bus cycles instruction and 2,048 in 4 bus cycles instruction.

 

 

Trace memory

Trace memory

 

 

 

 

 

 

Earliest instruction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(TP = 0)

 

 

 

 

 

 

 

 

 

 

 

Effective trace

 

 

 

 

 

 

 

Effective trace

 

 

(TP = 8,191)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Instruction just before break

Execution of

 

 

 

 

Instruction just before

 

 

 

 

 

 

 

Earliest instruction

 

 

 

 

 

 

 

 

 

 

 

a program

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

break (TP = 700)

 

 

 

 

 

 

 

(TP = 0)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Free space

 

 

 

 

 

 

 

Effective trace

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 5.7.1 Trace function

Figure 5.7.1 shows the trace function. When the trace memory is full, old information is erased and new information is overwritten. TP called trace pointer shows that the point of 0 means the earliest instruction and the break point means the latest information. The maximum value of the TP is 8,191.

Trace information

TP = 0

Earliest

instruction

Trace information at any point can be displayed by the TD command.

Latest

instruction

TP = 8,191

14

EPSON

S5U1C63000H2 MANUAL

 

 

(S1C63 FAMILY IN-CIRCUIT EMULATOR)