SAP-I has _______ T states, period during which register contents change
Six
Understanding SAP-I Processor T-States
The SAP-I (Simple Associated Processor I) is a basic processor model designed to help understand the core concepts of how a CPU executes instructions. It simplifies the complex processes found in real-world processors.
T-states are fundamental units of time in a processor's operation. Think of them as the smallest clock cycle intervals during which the processor can perform a specific, basic action. An entire instruction cycle, which is the complete process of fetching, decoding, and executing one instruction, is broken down into a sequence of these T-states.
Register Content Changes in SAP-I Operations
Processors use registers to temporarily store data, instructions, memory addresses, and control signals that are actively being used. Key registers include the Program Counter (PC), Accumulator, Instruction Register (IR), and Memory Address Register (MAR).
During the execution of any instruction, the values stored in these registers are often updated or changed. This happens during specific phases of the instruction cycle:
- Updating the Program Counter to point to the next instruction.
- Fetching instruction opcodes or data operands from memory into registers like the IR or Accumulator.
- Performing calculations (e.g., in the ALU), which modifies the Accumulator or status flags.
- Storing the results of operations back into registers.
In the specific case of the SAP-I model, there is a defined sequence of operations where these register updates occur. This specific period involves a set number of T-states.
For the SAP-I, the duration of the instruction cycle when register contents are actively modified spans Six T-states. These are the specific intervals dedicated to loading data, processing it, and updating register values according to the instruction being executed.
Illustrative T-State Activities in SAP-I
| Instruction Cycle Stage | Processor Actions Involving Registers | Conceptual T-States |
| Fetch Opcode | PC value sent to memory; IR receives opcode; PC increments. | T1, T2 |
| Fetch Operand | Address sent to memory; Data loaded into Accumulator or Register; PC might update. | T3, T4 |
| Execute Instruction | ALU computation; Result stored in Accumulator; Status flags updated. | T5, T6 |
Therefore, the SAP-I architecture defines a specific phase within its instruction cycle, consisting of Six T-states, primarily dedicated to the modification and updating of its internal registers.
Important Questions from Shift Register Counters
The number of unused states in a n-bit Johnson Counter is:
Depending on the counter, there are up to _________ modes available on high-speed counters.
If the registers have both shifts and parallel load capabilities, they are referred as _________.
The highest speed counter is
A Shift register in which the output of the last flip-flop is connected to the input of the first flip-flop
