AN910 Datasheet, PDF (16/51 Pages) STMicroelectronics – ST7 AND ST9 PERFORMANCE BENCHMARKING

ST7 AND ST9 PERFORMANCE BENCHMARKING
Table 4. Medium-end to low-end MCU strong and weak points
MCU
Strong points
68HC11
(4 MHz)
68HC08
(8 MHz)
instruction processing: 1-byte prefetch queue
fast 8-bit ALU:
8-bit datapath
625 ns 8x8 multiplication
short average ICT:
500 to 625 ns
special addr. modes: indexed with 8-bit offset or
post-increment
special instructions: compare & branch like
decrement & branch like
memory-to-memory moves
large memory space: up to 4 Mbytes with memory
expansion module
short average IL:
special addr. modes:
80C51 special instructions:
(20 MHz)
multitasking:
1 to 2 bytes
register indirect
stack pointer relative
compare & branch like
decrement & branch like
bit test & bit clear & jump
memory-to-memory moves
context switching capabilities
special addr. modes:
KS88
(8 MHz)
special instructions:
multitasking:
interrupt processing:
register pair
indirect register/address
indexed (short/long)
compare & increment &
branch like
decrement & branch like
context switching capabilities
nested mode
level priority control register
special addr. modes:
78K0
(10 MHz)
special instructions:
multitasking:
register indirect
stack pointer relative
indexed with 8-bit offset
decrement & branch like
context switching capabilities
Weak points
medium 8/16-bit ALU:
long average ICT:
lacking instructions:
multitasking:
2500 ns 8x8 multiplication
1500 to 1750 ns
compare & branch like
decrement & branch like
no special capabilities
lacking addr. modes: no indirect addressing
multitasking:
no special capabilities
slow 8-bit ALU:
long average ICT:
2400 ns 8x8 multiplication
900 to 1000 ns
slow 8-bit ALU:
3000 ns 8x8 multiplication
long average ICT:
1250 to 1500 ns
data memory location: off-chip only
mixed architecture:
slow 8-bit ALU:
long average ICT:
only accumulator oriented
3200 ns 8x8 multiplication
1400 to 1600 ns
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