AN910 Datasheet, PDF (33/51 Pages) STMicroelectronics – ST7 AND ST9 PERFORMANCE BENCHMARKING

ST7 AND ST9 PERFORMANCE BENCHMARKING
7.3.6 H8/300 MCU core
Programming model
Register file
- general registers
sixteen 8-bit registers
useable as eight 16-bit registers
include one 16-bit stack pointer
- others registers
16-bit program counter
condition code register
MOVE Rd,Rs
ADD Rd,#2
Instruction set
Risc encoding
- CPI
2 cycles to 24 cycles
- average CPI
between 5 and 6 cycles
- IL
2 bytes or 4 bytes (even)
- average IL
between 2 and 3 bytes
- special addressing modes
register access as bit, 4-bit, byte, or word
register indirect
with 16-bit offset
with pre/post-increment
- special instructions
block moves
H8/300 CPU
Cpu internal buses
16-bit address bus, 16-bit data bus
8-bit register bus (to be confirmed)
Instruction processing
Standard
- sequential processing
Arithmetic Logic Unit
+/x
8-bit datapath
- 8/16-bit operations
- special functions
8x8 unsigned multiplication
16/8 unsigned division
14 cycles
14 cycles
On-chip/Off-chip buses
- on-chip buses
16-bit address bus
8/16-bit data/program memory bus
- off-chip buses
8/16-bit address bus
8-bit data/program memory bus
the two buses are multiplexed with ports
Memory Space
Von Neumann organization
- linear data/program memory space
64 kbytes
upper 176-byte on-chip register field
additional 16-byte on-chip register field
first 48-byte interrupt vector table = 21 interrupts
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