Features of SAP-2 Computer with Block Diagram

SAP-2 (Simple As Possible - 2) is an advanced version of SAP-1 computer with extended instruction set, more registers, larger memory, and flag flip-flops, designed to bridge the gap between SAP-1 and commercial microprocessors.

Features of SAP-2

• Extended Instruction Set — SAP-2 has a larger set of instructions including arithmetic, logic, jump, and call instructions
• Larger Memory — It uses 16-bit address bus, allowing access to 64 KB of memory (compared to 16 bytes in SAP-1)
• 8-bit Data Bus — Transfers 8-bit data between components
• More Registers — Contains registers B and C in addition to the accumulator (A)
• Flag Flip-Flops — Has two flags: Sign flag and Zero flag, used for conditional jumps
• Bidirectional Bus — Uses a W-bus (bidirectional) for data transfer between all components
• Input/Output Ports — Has input ports (Port 1, Port 2) and output ports (Port 3, Port 4) for communication with external devices
• Hexadecimal Keyboard Input — Replaces the programming switches of SAP-1
• Unconditional and Conditional Jumps — Supports JMP, JZ (jump if zero), and JNZ (jump if not zero) instructions
• Subroutine Capability — Supports CALL and RET instructions

Block Diagram of SAP-2

Components Summary:

• PC (Program Counter) — 16-bit, can address 64KB memory
• MAR — 16-bit Memory Address Register
• IR — Instruction Register holds current instruction
• ALU — Performs ADD, SUB, AND, OR, XOR operations
• Accumulator (A), Register B, Register C — 8-bit data registers
• Flags — Sign and Zero flags for conditional branching
• Controller/Sequencer — Generates control signals for all operations
• Input/Output Ports — For external device communication

Sub-question: How is SAP-2 different from SAP-1? [2 marks]

In summary, SAP-2 is a significantly more powerful and practical computer compared to SAP-1, with larger memory, more registers, flags, and jump/subroutine capabilities.