Trace Buffer Information; Hardware Slipping On A Breakpoint - Intel l2ICE User Manual

Trace Buffer Information

For more information on the trace buffer, see the entries PRINT and Trace buffer display in the
FICE™ System Reference Manual.

Hardware Slipping On a Breakpoint

Because emulation is in real time, for the 8086/8088 and 80186/80188 probes you cannot
break exactly where you specified. To break on the execution of an instruction, the FICE
system must first recognize that the instruction is executing. (The 80286 probe has a special
feature that prevents hardware slipping.)
The following example illustrates hardware slipping.
* GO FROM begin Tit :cmeker#13 TRACE :anaker#12to :ctneker#13
fUNIT D PORT SH REQUESTS WORD INPUT (ENTER VALUE) =80
fUNIT □ PORT 4H REQUESTS U0RD INPUT (ENTER VALUE) =75
Probe □ stopped at :CNAKER#13 + 3 because of execute break
The FICE system is designed to break right after the execution of the specified instruction, and
specifying statement #13 specifies the first assembly language instruction making up statement
#13. The FICE system informs you that the probe stopped three bytes past the beginning of
statement #13. The trace buffer gives you more information.
* PRINT INSTRUCTIONS ALL
FRAME ADR
: CMAKER#12
□DO D0ais0D3FH
DDai:DD43H
□04
00b 00S1S0045H
:CMAKER#13
00A DOSlsOOMIH
0Q0444H-DU-0005H
00C 0 0 2 1 : Q04BH
The FICE system slipped three bytes. The first two bytes make up the instruction MOV
AX,CX. These are bytes :CMAKER#13 + 0 and :CMAKER#13 +1. The next byte
(:CMAKER#13 + 2) is the instruction CWD. Execution will resume at :CMAKER#13 + 3.
Introduction to Using the PICE™ System
MNEMONICS
BYTE
M ABDEIEDO
M SBCfl
fl^OEOMOO
flBCl
OPERANDS
MOV CXnltlORD PTR0012H
SUB CX-.AX
MOV WORD PTR 0004H-.CX
MOV AX.CX
CUD
UNIT 0
3-43