User'am - Risc processor - the path to the future.

<b>User'am</b> - Risc processor - the path to the future.

(C) 1998 by Spider

Music by Andrew Fer


           RISC-WAY TO THE FUTURE



              ACT 20/80


  Appeared in the early seventies
microprocessors, but rather designed to
the basis of their computers, did not seem to be able to
compete with the professional computing devices. Indeed, the 8 
- bit micro-computer with a microprocessor 8080, Z-80 or 6502 
(Apple, TRS-80, Vic20 i.t.p) could not make any competition or 
more computers, which manufactured by IBM, CDC, or Burrought, 
nor 16 - bit minicomputers.



  Packard DEC, Data General and HewlettPackard. Picture began 
to change with the advent of 16-bit microprocessors INTEL 8086 
and 32-bit Motorola 68000. Personal computers that use these

microprocessors (IBM PC and Apple
Macintosh), is quite able to compete
to large computers about a decade ago.


  On the first day of a microprocessor
constantly were searching for ways to enhance their
performance. Improved
technology has increased the number of
transistors on a chip, and their density
location, the clock speed and efficiency of instruction. 
Developed an optimal system commands. And in this directions 
promotion was the most significant.




  Initially it was thought that the richer the command system, 
the more effective working computer. Advertisement 
microprocessors were exactly this way. Each team in the

Interpretation spawned the performance of many
(Sometimes tens or even hundreds) of elementary
microinstructions. Therefore, most of the time,
required to develop a new
microprocessor, was spent on debugging microinstructions. And, 
as a rule, even in serial specimens of microprocessors early or 
later to identify those or other errors. Recall that the error 
microcode processor INTEL 80386 and 80486 have been removed 
only after more than a year after their appearance on the 
market. 

Microprocessors traditional architecture
(Firms INTEL, Motorola, National
Semiconductors, Zilog) were named
CISC (Complicated Instuction Computer using a complex set of 
commands.) 

Intensive testing of the various
processors in the performance and a variety of
tasks carried out by many developers
computers, showed that the processors
very well applicable law, which stated as follows: "20 percent 
of the population drinks, 80 percent of beer. "In our case, 
this means that mostly in the calculations computers" grind 
"are one and the same instructions from a small subset of the 
complete system of commands. In the first turn this team reads 
and writes to memory and the transition team. Therefore, to 
accelerate works naturally to optimize the performance of these 
particular teams. As for other, more complex and rarely used, 
then the majority can opt out. 


          ALL JUST genius


  Microprocessors are the new architecture were called RISC 
(Reduced Instruction Computer-PC with a reduced to a minimum 
set of commands). It made special measures to accelerate the 
execution of these few commands. Technology development of 
microprocessors, computers their basis and mathematical software

for them, became known as RISC-technology.


  What the team needed, and what
You can (and should) be sacrificed for the sake of speed? The 
answer is obvious: if by reducing the number of commands 
"challenging" command (eg "add a constant to the contents of 
memory") will be possible to replace a sequence of simpler 
("load the contents of the memory cell in the register, "" add 
a constant to the contents of the register ") which are faster, 
then this "Sophisticated" command can be successfully

excluded in the first "reduction"
As for the commands to access memory. In the RISC
-Processors are typically used
Only teams memory-register transfers and
register memory. All arithmetic and logical operations and 
conversions are carried out only with data located in registers.


 In 1975 the architect supercomputer CDC and the creator of the 
most productive in the world of computers Cray American 
engineer Seymour Cray, said: "The registers do machine 
instructions are very simple. This is something unique. Most 
machines use command system with a much larger variety of 
methods of addressing memory than those that I developed. In my 
opinion, true path is prostota.Ya entirely for simplicity.

If the command system is too complicated, I did
just do not understand. "


  Thus, the ideological foundation RISC-Technology was founded 
in the mid seventies. The first true RISC-PC was

created in 1979 by IBM. This 32razryadny computer, called
IBM 801, was built on chips ECL,
had 32 registers, instruction set, most of which was executed 
in one machine tact.



  The term RISC was first proposed
Professor David Patterson, in his lectures on microprocessor 
technology, delivered in 1980 GV University of California at 
Berkeley. There was also initiated the development of the 
processor RISC I, which was completed in 1982 Two years later

appeared processor RISC II. His main
Features: 32 bit word length, number of registers 138, clock 
frequency, 3 MHz. Even without special compilers, performance 
of the new microprocessor with perform operations with whole 
numbers to be higher than that of the widespread 
super-minicomputer VAX 11/780 



  Shortly after beginning work at Berkeley,
Stanford University team led by John Hennessy
started to develop the project, known as MIPS (Miroprocessor 
without Interlocked Pipeline Stages-microprocessor pipelines 
without delay, while at the same time, the MIPS acronym stands 
for "million instructions per second). Stanford MIPS

was a 32-bit microprocessor with 16 registers and a clock 
frequency of 2 MHz. This processor family was the basis of 
commercial RISC-processor, manufactured by the same name-MIPS. 


  Processors with a RISC-architecture produced
and other firms: Ridge, Pyramid, HewlettPackard. A special 
place (both from a technical and economic point of view) among

They took the family of microprocessors
SPARC (Scalable Processor Architecture Processor 
ARChitecturemasshtabiruemaya) developed by Sun Microsystem. On

example of this particular family of microprocessors we will 
introduce in more detail the architecture of RISC. 


                 to be continued ...