
3
PC755/745
2138D–HIREL–06/03
General Parameters
The following list provides a summary of the general parameters of the PC755:
Features
This section summarizes features of the PC755’s implementation of the PowerPC archi-
tecture. Major features of the PC755 are as follows:
Branch Processing Unit
–
Four instructions fetched per clock
–
One branch processed per cycle (plus resolving 2 speculations)
–
Up to 1 speculative stream in execution, 1 additional speculative stream in
fetch
–
512-entry branch history table (BHT) for dynamic prediction
–
64-entry, 4-way set associative Branch Target Instruction Cache (BTIC) for
eliminating branch delay slots
Dispatch Unit
–
Full hardware detection of dependencies (resolved in the execution units)
–
Dispatch two instructions to six independent units (system, branch,
load/store, fixed-point unit 1, fixed-point unit 2, floating-point)
–
Serialization control (predispatch, postdispatch, execution serialization)
Decode
–
Register file access
–
Forwarding control
–
Partial instruction decode
Completion
–
6 entry completion buffer
–
Instruction tracking and peak completion of two instructions per cycle
–
Completion of instructions in program order while supporting out-of-order
instruction execution, completion serialization and all instruction flow
changes
Fixed Point Units (FXUs) that share 32 GPRs for Integer Operands
–
Fixed Point Unit 1 (FXU1)-multiply, divide, shift, rotate, arithmetic, logical
–
Fixed Point Unit 2 (FXU2)-shift, rotate, arithmetic, logical
Technology
0.22 μm CMOS, six-layer metal
6.61 mm x 7.73 mm (51 mm
2
)
Die size
Transistor count
6.75 million
Logic design
Fully-static Packages
PC745
Surface mount 255 Plastic Ball Grid Array (PBGA)
Surface mount 360 Plastic Ball Grid Array (PBGA)
Surface mount 360 Ceramic Ball Grid Array (CI-CGA, CBGA,
HiTCE)
2V ± 100 mV DC (nominal; some parts support core voltages
down to 1.8V; see Table 5 for recommended operating
conditions)
2.5V ± 100 mV DC or 3.3V ± 165 mV DC (input thresholds are
configuration pin selectable)
PC755
Core power supply
I/O power supply