2. Microprocessor
• It is a multipurpose, programmable device that
accepts digital data as input, processes it according to
instructions stored in its memory, and provides
results as output. Microprocessors operate on
numbers and symbols represented in the binary
numeral system.
4. Clock cycle and Microprocessor
speed
• Clock cycles are used as a timing reference for a microprocessor (just
like we use clocks to manage timing of our daily works).
• Each microprocessor task may take a number of clock cycles.
• So a Microprocessor which can do more clock cycles in a particular
time can achieve any task faster.
• That’s why a 3.6 GHz microprocessor (which does 3.6x109 clock
cycles per second) is faster than a 2.4 GHz microprocessor.
• Can you show the time (on X-axis) for each of the two
microprocessors mentioned in the previous line? (I showed in the
class). See the figure on the previous slide for some hints.
5. Microprocessor bit
• The 64-bit processors have been with us since 1992, and in 21st century
they have started to become mainstream. Both Intel and AMD have
introduced 64-bit chips. The 64-bit processors have 64-bit ALUs, 64-bit
registers, 64-bit buses and so on.
• One reason why the world needs 64-bit processors is because of their
enlarged address spaces. The 32-bit chips are often constrained to a
maximum of 2^32 = 2^30 × 2^2 = 4GB of RAM access. That sounds
like a lot, given that most home computers currently use only 256MB to
512MB of RAM. However, a 4GB limit can be a severe problem for
server machines and machines running large databases.
7. Microprocessor progression
(howstuffworks.com)
• Transistors is the number of transistors on the chip.
You can see that the number of transistors on a
single chip has risen steadily over the years.
• Microns is the width, in microns, of the smallest
wire on the chip. For comparison, a human hair is
100 microns thick. As the feature size on the chip
goes down, the number of transistors rises.
8. Microprocessor progression
• Clock speed is the maximum rate that the chip can be clocked at. Clock speed will make more sense in
the next section.
• Data Width is the width of the ALU. An 8-bit ALU can add/subtract/multiply/etc. two 8-bit numbers,
while a 32-bit ALU can manipulate 32-bit numbers. An 8-bit ALU would have to execute four
instructions to add two 32-bit numbers, while a 32-bit ALU can do it in one instruction. In many cases,
the external data bus is the same width as the ALU, but not always. The 8088 had a 16-bit ALU and an 8-
bit bus, while the modern Pentiums fetch data 64 bits at a time for their 32-bit ALUs.
• MIPS stands for "millions of instructions per second" and is a rough measure of the performance of a
CPU. Modern CPUs can do so many different things that MIPS ratings lose a lot of their meaning, but
you can get a general sense of the relative power of the CPUs from this column.
9. Microprocessor progression
• From the table in the figure you can see that, in general, there is a
relationship between clock speed and MIPS. The maximum clock
speed is a function of the manufacturing process and delays within the
chip. There is also a relationship between the number of transistors
and MIPS. For example, the 8088 clocked at 5 MHz but only executed
at 0.33 MIPS (about one instruction per 15 clock cycles). Modern
processors can often execute at a rate of two instructions per clock
cycle. That improvement is directly related to the number of
transistors on the chip
10. Moor’s law (Gordon Moore is
Intel co-founder)
• The number of transistors incorporated in a chip will
approximately double every 24 months.
• The implication of this law is that the processing
power of microprocessor also increase.
11. Multi Core Processors
• Each cores execute a separate task in a program. This
increases the speed of execution.
• Intel recently demonstrated a version of the Core 2
that contains 80 cores.
12. Future of Microprocessors
• It’s hard to make predictions.
• A new technology jointly developed by Intel and HP may
occur. It’s called Hyper threading. With this technology, many
microprocessors communicate directly with each other,
allowing parallel processing without any change to the
instruction set or program.
• This technology will allow parallel processing without writing
any special programs.
• Along with these, the speed of RAM and data transfer speed
of mass storages may increase.
14. Cache memory
• Cache memory is random access memory (RAM)that a computer
microprocessor can access more quickly than it can access regular RAM. As
the microprocessor processes data, it looks first in the cache memory and if it
finds the data there (from a previous reading of data), it does not have to do
the more time-consuming reading of data from larger memory.
• Cache memory is sometimes described in levels of closeness and accessibility
to the microprocessor. An L1 cache is on the same chip as the microprocessor.
L2 is usually a separate static RAM (SRAM) chip.
