Microprocessor and Microcontrollers (CSE-3511) Lecture-1

1. Microprocessor and Microcontrollers (CSE-3511)Lecture-1 Instructor: SazidZaman Khan Lecturer, Department of Computer Science and Engineering, IIUC

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. It is an example of sequential digital logic, as it has internal memory. Microprocessors operate on numbers and symbols represented in the binary numeral system.

3. Clock cycle 1 clock cycle (1 period)

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.

6. Microprocessor progression

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. • This is called multithreading. • 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.

13. Conceptual view of Microprocessors Figure 1: Conceptual view of Microprocessors (Brey-16P)

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.