Embedded System Architecture Learning Notes (2) __ Embedded

  Monday, October 29, 2007   Introduction 0         von Neumann computer system l          operator, controller, memory, input, output l         binary representation program and data l          program and data stored in memory, computer automatic execution 1)         CPU The CPU consists of a controller and an operator l         controller: Unified Command and coordination of the work of all parts of the computer to complete the various operations specified by the computer program. It is composed of program counter, instruction register, decoder, operation control part and so on. l         Operator: arithmetic logic unit (ALU), accumulator Register, Universal Register, etc. The function is to complete arithmetic operations and logical operations. l         Performance: n         The computer motherboard has a clock signal generator, the generator generates a clock signal frequency of the system bus frequency, also known as FSB n         CPU main frequency called the internal clock frequency. The n         internal frequency is a multiple of the FSB, called the frequency multiplier factor. For example, the Pentium 4CPU uses 400MHz FSB, the multiplier factor is 7, then obtains the 2.8G frequency. 2)         Internal memory l         type: Rom,ram, EeproM,flash. l         internal memory for special functions: n         BIOS: A ROM chip that holds the system program. There are two main uses: u       start computer, power self-test, boot operating system u       Drivers that contain basic input. n         CMOS System configuration Memory: Special RAM, with rechargeable battery power. Long-term storage of machine system basic configuration information. n         Cache Cache Memory: usually by the fast access speed of SRAM composition, capacity is generally 64kb~1mb, high-speed The interface between the CPU and the relatively low speed RAM. Work, the current to perform the program segment and data transfer to the cache, the CPU read and write first access cache, can minimize the access to the RAM and the time spent waiting. 3)         computer is operated by "program Storage" and "programmed control". 4)         [a ~ z] = [ 97, 122]      [a ~ z] = [65,     [0 ~ 9] = [m]     NUL = 0