AN910 Datasheet, PDF (38/51 Pages) STMicroelectronics – ST7 AND ST9 PERFORMANCE BENCHMARKING

ST7 AND ST9 PERFORMANCE BENCHMARKING
7.3.11 KS88 MCU core
Programming model
Register file
- prime registers
192 8-bit prime data registers
- two register sets
register set 1
sixteen 8-bit working registers
sixteen 8-bit system registers
32 8-bit system & peripheral control registers
register set 2
64 registers
- other registers
16-bit program counter
system and user stack pointers
- multitasking capabilities
context switching with register sets
system and user modes
MOVE Rd,Rs
ADD Rd,#2
Instruction set
Cisc encoding
- CPI
6 cycles to 28 cycles
- average CPI
between 10 and 12 cycles
- IL
1 byte to 3 bytes
- average IL
between 2 and 3 bytes
- special addressing modes
register pair (two 8-bit registers as one 16-bit)
indirect address/register
indexed (short/long)
- special instructions
compare & increment & branch like
decrement & branch like
KS88 CPU
Core internal buses
16-bit address bus, 8-bit data bus
8-bit register bus (to be confirmed)
Instruction processing
Standard
- sequential processing
Arithmetic Logic Unit
+/x
8-bit datapath
- 8-bit operations
- special functions
8x8 unsigned multiplication
16/8 unsigned division
24 cycles
28 cycles
On-chip/Off-chip buses
- on-chip buses
8/16-bit address bus
8-bit program memory bus
8-bit register bus
- off-chip buses
8/16-bit address bus
8-bit data/program memory bus
the two buses are multiplexed
the two buses are multiplexed with ports
Memory Spaces
Von Neumann organization
- register file space
192-byte prime data register space (all addr. modes)
64-byte register set 1
16-byte working register space (working reg. addr.)
16-byte system register space (register addressing)
32-byte system & peripheral control register space
(register addressing)
64-byte register set 2
64-byte data register space (indirect, indexed, stack)
- linear data/program memory space
64 kbytes
first 16-Kbyte program memory only
first 256-byte interrupt vector table = 128 interrupts
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