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Chapter 1 Architectural Overview
1.14.1 The Simulation Event File
Simulation is driven by modeling the 29K processor pipeline operation. Instruc-
tions are fetched from memory, and make their way through the decode, execute and
write–back stages of the four–stage pipeline. Accurate modeling of processor inter-
nals enables the simulator to faithfully represent the operation of real hardware.
The simulator can also be driven from an event file. This file contains com-
mands which are to be performed at specified time values. All times are given in pro-
cessor cycles, with simulation starting at cycle 0. The simulator examines the event
file and performs the requested command at the indicated cycle time.
The syntax of the command file is very simple; each command is entered on a
single line preceded with a integer cycle–time value. There are about 15 to 20 differ-
ent commands; most of them enable extra information to be placed in the simulation
results file. Information such as recording register value changes, displaying cache
memory contents, monitoring floating–point unit operation, and much more. A se-
cond group of commands are mainly used with microcontroller 29K family mem-
bers. They enable the on–chip peripheral devices to be incorporated in the simula-
tion. For example, the Am29200 parallel port can
receive
and
transmit
data from files
representing off–chip hardware.
In practice, most of these commands are little used; with one exception, the SET
command (see note below). Most users of
sim29
simply wish to determine how a
code sequence, representative of their application code, will perform on different
29K family members with varying memory system configurations. The SET com-
mand is used to configure simulation parameters and define the characteristics of
system memory and buss arrangements. I will only describe the parameters used with
the MEM option to the SET command.The cycle–time value used with the com-
mands of interest is zero, as the memory system characteristics are established before
simulation commences. One other option to the SET command of interest is
SHARED_ID_BUS; when used, it indicates the Instruction and Data buses are con-
nected together. This option only makes sense with 3–bus members of the 29K fami-
ly. All the 2–bus members already share a single bus for data and instructions, the
second bus being used for address values. The syntax for the commands of interest is
show below:
0
0
SET_SHARED_ID_BUS
SET MEM
access
TO
value
Note, the SET command is accepted by both the older and newer versions of the
simulator. However, the newer version has an abbreviation to the SET command
shown below; the “SET MEM” syntax is replaced by a direct command and there is
no need for the “TO”.