SESSION 8 –MARIE - Stony Brook Universityise218/Slides/L08-MARIE.pdf · buffer register •permits data transfer between these devices without use of the main data bus ... •Specified
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L08 - MARIE 10/3/2016
1
ISE218 – Fundamentals of Information Technology
SESSION 8 – MARIEReading: Sections 4.8-4.11
Objectives• Better understand the operations of a computer by examining a very simple processor that includes many important features of a processor
• Understand the major components (control unit, registers, memory, ALU, and data path)
MARIE Characteristics• Binary, two's complement data representation• Stored program, fixed word length data and instructions• 4K words of word-addressable main memory• 16-bit data words• 16-bit instructions, 4 for the opcode and 12 for the
address• A 16-bit arithmetic logic unit (ALU)• Seven registers for control and
data movement
2 bytes per word2 bytes per word
Opcode is the numeric value of the operation (e.g., Load Register)
Opcode is the numeric value of the operation (e.g., Load Register)
MARIE Architecture• Registers are interconnected, and connected with main memory through a common data bus
• Each device on the bus is identified by a unique number that is set on the control lines whenever that device is required to carry out an operation
• Separate connections are also provided between the accumulator and the memory buffer register, and the ALU and the accumulator and memory buffer register• permits data transfer between these devices without
• memory with a 32-bit word• 110 different instructions• 8 general purpose registers• All instructions have 3 parts: op code, memory address
and register address• Questions
• How many bits for the op code in an instruction?• How many bits to specify the register in an instruction?• How many bits for the memory address in an
instruction?• What is the maximum size of the memory (in bytes)?
Interrupt Handling• It is common to disable all interrupts during the time in which an interrupt is being processed.• Typically, this is achieved by setting a bit in the flags
register• Interrupts that are ignored in this case are called maskable
• Nonmaskable interrupts are those interrupts that must be processed in order to keep the system in a stable condition
More advanced processors support more advanced interrupt handling features
More advanced processors support more advanced interrupt handling features
Have You Satisfied Objectives?• Better understand the operations of a computer by examining a very simple processor that includes many important features of a processor
• Understand the major components(control unit, registers, memory, ALU, and data path