| 词条 | CompactRISC |
| 释义 |
CompactRISC is a family of instruction set architectures from National Semiconductor. The architectures are designed according to reduced instruction set computing principles, and are mainly used in microcontrollers.[1] The subarchitectures of this family are the 16-bit CR16 and CR16C and the 32-bit CRX.[2] CR16 architecturesFeatures of CR16 family: compact implementations (less than 1 mm2 with 250nm), addressing of 2 MB (2^21), frequencies up to 66 MHz, hardware multiplier for 16-bit integers.[1] It has complex instructions such as bit manipulation, saving/restoring and push/pop of several registers with single command.[1] CR16 has 16 general purpose registers of 16 bits, and address registers of 21 bits wide. There are 8 special registers: program counter, interrupt stack pointer ISP, interrupt vector address register INTBASE, status register PSR, configuration register and 3 debug registers. Status register implements flags: C, T, L, F, Z, N, E, P, I.[1] Instructions are encoded in two-address form in several formats, usually they have 16-bit encoding, but there are two formats for medium immediate instructions with length of 32-bit. Typical opcode length is 4 bits (bits 9-12 of most encoding types. Basic encoding formats are: Register-to-Register, Short 5-bit immediate value to Register, Medium immediate of 16-bit value to Register (32 bit encoding), Load/Store relative with short 5-bit displacement (2 bit opcode), Load/Store relative with medium 18-bit displacement (32 bit encoding, 2 bit opcode).[1] CR16C comes with a different opcode encoding format, has 23-32bits wide address registers and provides two 32bit general purpose registers.[3] CR16 implements traps and interrupts. Implementations of CR16 has three-stage pipeline: Fetch, Decode, Execute.[1] CR16 productsCR16 was used in several National Semiconductor microcontrollers, and since 2001 integrated microcontrollers were available having built-it flash memory.[4][5] Since 2007 CR16-based IP was available to licensing[6] References1. ^1 2 3 4 5 {{cite web|url=http://www.eng.utah.edu/~cs3710/slides/cr16x2.pdf|title=National Semiconductor CR16, Compact RISC Processor, Baseline ISA and Beyond|last=Brunvand|first=Erik |work=CS/EE 3710|publisher=University of Utah |accessdate=3 December 2016}} 2. ^{{cite book|last=von Hagen|first=William |title=The Definitive Guide to GCC|publisher=Apress|date=2011|page=422|isbn=9781430202196|url=https://books.google.com/books?id=wQ6r3UTivJgC&pg=PA422&lpg=PA422&dq=national+cr16+crx&}} 3. ^{{cite web|url=https://dump.bitcheese.net/files/zujukix/Prog_16C.pdf|title=CR16C Programmer’s Reference Manual}} 4. ^{{cite news|url=http://www.eetimes.com/document.asp?doc_id=1128340|title=National Semi's 16-bit MCU integrates flash, analog|last= Graham|first=Jeanne |publisher=EETimes|accessdate=3 December 2016|date=2001-02-22}} 5. ^{{cite news|url=http://www.eetimes.com/document.asp?doc_id=1290094|title=National's 16-bit RISC MCU touts high-endurance flash|date=2001-03-13|publisher=EETimes|accessdate=3 December 2016}} 6. ^{{cite news|url=http://www.eetimes.com/document.asp?doc_id=1240853|title=NatSemi taps IPextreme for embedded IP resale|last=Hammerschmidt|first=Christoph |date=2007-02-21|publisher=EETimes|accessdate=3 December 2016}} External links
1 : Microcontrollers |
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