Chapter 4 - The Von Neumann Model. The following will be discussed in this chapter: Basic components, The LC-3: An example Von Neumann machine, instruction processing, stopping the computer. | Chapter 4 The Von Neumann Model The Stored Program Computer 1943: ENIAC Presper Eckert and John Mauchly -- first general electronic computer. (or was it John V. Atananasoff in 1939?) Hard-wired program -- settings of dials and switches. 1944: Beginnings of EDVAC among other improvements, includes program stored in memory 1945: John von Neumann wrote a report on the stored program concept, known as the First Draft of a Report on EDVAC The basic structure proposed in the draft became known as the “von Neumann machine” (or model). a memory, containing instructions and data a processing unit, for performing arithmetic and logical operations a control unit, for interpreting instructions For more history, see 4- Von Neumann Model 4- Memory k x m array of stored bits (k is usually 2n) Address unique (n-bit) identifier of location Contents m-bit value stored in location Basic Operations: LOAD read a value from a memory location STORE write a value to a memory location • • • 0000 0001 0010 0011 0100 0101 0110 1101 1110 1111 00101101 10100010 4- Interface to Memory How does processing unit get data to/from memory? MAR: Memory Address Register MDR: Memory Data Register To read a location (A): Write the address (A) into the MAR. Send a “read” signal to the memory. Read the data from MDR. To write a value (X) to a location (A): Write the data (X) to the MDR. Write the address (A) into the MAR. Send a “write” signal to the memory. 4- Processing Unit Functional Units ALU = Arithmetic and Logic Unit could have many functional units. some of them special-purpose (multiply, square root, ) LC-2 performs ADD, AND, NOT Registers Small, temporary storage Operands and results of functional units LC-2 has eight register (R0, , R7) Word Size number of bits normally processed by ALU in one instruction also width of registers LC-2 is 16 bits 4- Input and Output Devices for getting data into and out of computer memory Each device has . | Chapter 4 The Von Neumann Model The Stored Program Computer 1943: ENIAC Presper Eckert and John Mauchly -- first general electronic computer. (or was it John V. Atananasoff in 1939?) Hard-wired program -- settings of dials and switches. 1944: Beginnings of EDVAC among other improvements, includes program stored in memory 1945: John von Neumann wrote a report on the stored program concept, known as the First Draft of a Report on EDVAC The basic structure proposed in the draft became known as the “von Neumann machine” (or model). a memory, containing instructions and data a processing unit, for performing arithmetic and logical operations a control unit, for interpreting instructions For more history, see 4- Von Neumann Model 4- Memory k x m array of stored bits (k is usually 2n) Address unique (n-bit) identifier of location Contents m-bit value stored in location Basic Operations: LOAD read a value from a memory location STORE write a value to
