From the fanar - RISC processors - THE WAY TO THE FUTURE.

  RISC-PATH TO THE FUTURE         
                                        
           Law 2O/8O              
                                        
 Appeared in the early seventies
microprocessors, or rather developed
based on them, computers seemed unable to
gut to compete with professional you-
numerical technology.      Action
Specifically, 8-bit microcomputers on micro-
processors  8O8O,Z-8O  or 65O2
(Apple,TRS-8O,Vic-2O, etc.)could not
pose any competition
large computers that produced
companies IBM, CDC or Burrought,nor 16 times
in-line minicomputers from DEC, Data General and
HewlettPacKard. The picture began to change from
the advent of 16-bit microprocessors
ditchINTEL8O86and 32-bitMotorola 68
OOO. Personal computers, I use-
What are these microprocessors (IBM PC and Apple
Macintosh), could already compete
work with mainframe computers from ten years ago
tee.                                     
                                        
 From the first day of microprocessor creation
We were constantly looking for ways to improve
their performance. Improved
technology, the number increased
transistors on chip and density
their location, clock frequency and efficiency
efficiency of instructions execution.
an optimal co-system was developed
mand. And progress in this direction
turned out to be the most significant.        
                                        
 At first it was believed that the richer the system
command theme, the more efficiently it works
computer.  And the creators of microprocessors
followed exactly this path. Each team
upon interpretation generated execution
many (sometimes tens and even hundreds)
elementary microcommands. Therefore, the basic
time spent on development
new microprocessor, went into debugging
microcommands. Moreover, as a rule, even in
serial copies of microprocessors
sooner or later certain
errors. Remember that  microcode errors
INTEL 8O386 and 8O486 processors were
were eliminated only after more than a year
after their appearance on the market.  Microprocessors of traditional architecture
ry (from INTEL, Motorola, National
Semiconductors,Zilog)  were named
CISC (Complicated Instruction Set
Computer-using a complex set of co-
mand).                                  
                                        
 Intensive testing of various
processors when executing various
different tasks, carried out by many developers
computer nerds, showed that
processors are very well suited for
con, which is formulated as follows: "2O pro-
cents of the population drinks 8O percent
beer". In our case, this means that in
mainly when performing calculations, computers "re-
"repair" the same instructions from
a small subset of the complete system
commands. First of all, these are commands to read
memory-recording and transition commands
Dov.Therefore, to speed up the work of the EU-
effectively optimize the execution of names
but these commands. As for the os-
tal, more complex and rarely used
tions, then from most of them you can
generally refuse.                        
                                        
       EVERYTHING GENIUS IS SIMPLE Microprocessors of new semi-architecture
Chile nameRISC (Reduced Instruction
Set Computer-computers with abbreviated to
minimum set of commands).At the same time
special measures have been taken to speed up
execution of these few commands.Technical
nology for the development of such microprocessors
rov, computers based on them and mathematics
technical support for them has become called
vatiRISC technology.                 
                                        
 Which commands are needed and which ones?
can and should be sacrificed in the name of the
grow?  The answer is obvious: if due to juice
increasing the number of commands "complex" command
(for example, "add a constant with the contents
memory") may turn out to be a possible replacement
thread into a sequence of simpler ones
("load the contents of a memory cell into
register","add constant to contents-
my register"), which are executed
faster, which means this “complex” command can-
can be successfully excluded. First
the "reduction" queue concerns the commands about -
access to memory. InRISCprocessors as
As a rule, only commands are used
memory-register and register-memory transfers.
All arithmetic, logical operations and
transition operations are carried out only
withdata contained in registers.     
                                        
 Back in 1975 chief architect super
computersCDCand the creator of the most
drivers in the world of computersCrayame-
Rican engineer Seymour Cray wrote:"Re-
hysters make machine commands very
simple. This is something universal
cal.Most machines use
command systems with much greater diversity
different memory addressing methods than those
which I developed. In my opinion, true
the way is simplicity. I am all for simplicity.
If the command system is too complex, I will
I just don't understand."                     
                                        
 So, the ideological basisRISC-technology would be
la was founded back in the mid-seventies
thousand. The first real RISC-computer
was created in  1979.  by IBM.This
A 32-bit computer called
nieIBM 8O1, was built on microcircuits
ESL, had 32 registers set of co-
mands, most of which were performed for
one machine cycle.The term RISCwas first proposed
Professor David Patterson in his
course of lectures on microprocessor technology
ke, read in 198G. in California
University in Berkeley. It was also started there
that development of the RISC I processor, which
was completed in 1982. Two more years
later, the  RISC II processor appeared.
main characteristics: bit depth-32
bits, number of registers - 138, clock hour -
tota-3 MHz. Even without special compilation
tor performance of the new micro-
processor when performing operations with the
in low numbers turned out to be higher than that of wide
common superminicomputer
VAX 11/78O.                             
                                        
 Soon after work began in Berkeley,
Stanford University group of specialists
alists under the leadership of John Hennesy
began developing the project, having received
Our name  MIPS (Microprocessor
without InterlocKed Pipeline Stages-mic-
roprocessor with a pipeline without delays; in
At the same time, the abbreviation MIPS stands for
"millionoperations per second"). 
FordMIPSwas a 32-bit micro-
processor with 16 registers and clock
totoy2MHz.This processor became the basis
families of commercialRISC-process-
ditch produced by a company with the same name
nim-MIPS.                             
                                        
 Processors withRISCarchitecture released
whether other companies
we:Ridge, Pyramid, HewlettPacKard. Special
place (both technically and economically)
from a technical point of view) among them ranks
family of microprocessorsSPARC
(Scalable Processor ARChitecture-scale-
processor architecture), once developed
developed by the companySun Microsystems.
at least microprocessors of this particular
family we will get to know in more detail
architectureRISC.                      
                                        
           RISC ARCHITECTURE           
                                        
 MicroprocessorsSPARCform a whole
family and are produced by a number of companies. They
find application in a wide variety of
computers from laptops to high-speed
growth vector super-mini. In these micro-
roprocessors use all the main
ideas that ensure high productivity
activity:                              
                                        
 -most commands are executed in one
CPU cycle;                        
                                        
 -completely absent or very limited
The amount of microcode is small, because microinstructions
add an extra level of complexity,
leading to loss of productivity;    
                                        
 -working with memory is limited to the operating system -
tions of memory-registration transfer.  All os-
tal operations are performed on data
in registers;                            
                                        
 -simplified set of instructions, mainly
essentially fixed format, and sharply
limited number of memory addressing methods
ti;                                     
                                        
 - a conveyor is used, i.e.  set
instructions is designed in such a way that it allows one
perform at the same timeseveral commands;  
                                        
 -RISC-processors use at least
32 registers and cache memory is enough
large volume;                        
                                        
 - complex functions from the transition equipment
refer to software, in other words -
we, it is in the programs that the pos-
sequences of commands that perform
complex functions that are in CISC-process-
rah are executed by microcommands hardwired into
processor.                              
                                        
 Let's see what the implementation of these gives
principles. Let's analyze the gain in speed
grow quantitatively. Productivity
microprocessor can be expressed
formula:                               
                                        
  P=S/(I*C),where P is performance,
S-processor clock frequency, I-coefficient
tient taking into account the increase in the number of you-
complete instructions due to modeling
complex commands (not present in
RISC processors),C-cycle average
processor required to execute
instructions.   Let's compare performance
32-bit CISC INTEL processors
8O386,Motorola 68O3Oand RISC processor
SPARC.                                  
                                        
 Parameters S,I,C and P for these three pro-
processors are given in the table.           
                                        
processor S, MHz I,% C, ins P, ins/sec 
                                        
                                        
Motorola 25 1OO 5.2 4.8     
 68OЗO                                  
                                        
INTEL 2O 11O 4.4 5.2     
8O386                                   
                                        
SPARC 25 12O 1.3 16      
                                        
 So, we see that "all other things being equal"
RISC-processor is far ahead of CISC.
Therefore, manufacturers of CISC-processors
introduce RISCelements into their new processors
cops.   For example,CISC-developed by the company
INTEL processor i486,while maintaining compatibility
bridge with their predecessors, all
is closer to RISC: it has significant
The number of machine tools has been significantly reduced
cycles spent on the execution of the main
new commands, cache memory introduced, improved
for the organization of conveyor processing
commands                                 
                                        
 Regarding RISC-processors of the family
SPARC,this is a feature of their architecture
guarantees full compatibility of the software
cookies for microprocessors of this se-
family. Microprocessors of this family
may have different amounts of re-
gisters, various hardware implementations
tion, but they all ensure execution
the same programs.                
                                        
 These microprocessors today
day most common in the world
RISC-processors. Developed by Sun
Microsystemsthey are licensed by this company
are produced by such well-known manufacturers
telics of integrated circuits, such asFujitsu,Texas Instruments Cypressand row-
the home of others.                             
                                        
 Produced as microprocessors with so-
frequency 2OMHz, made according to technical
CMOS technologies used in pornography
native computers such asLaptopand most
cheaper workstations, and
ESL microprocessor complexes with clock
howl frequency 8OMHz  (Bipolar company
Integrated Technology),manufactured
the efficiency of which reaches65 MIPS.
development of microprocessor
complexes with productivity up to25O
MIPS.