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A basic ALU design for my personal projects.


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prossesor-16-bit

[ Under Development ]

This is a 16-bit processor with 18 instructions of length 16 bit, 16 registers of size 16 bit and only the primary cache in its architecture.


[ Instruction Set ]

from 0 to f
0 is also known as ra as its used for jump and link and jump register

instructions

0000 0XXX XXXX XXXX    - no-op     X can be anything- no operation
0000 1XXX XXXX XXXX    - jmp   X is the address offset from pc  - jump
0001  XXXX YYYY YYYY    - lli   X is the register to write data to and Y is the data to load in lower 8 bits- load lower imediate
0010  XXXX YYYY YYYY    - orui  X is the register to write data to and Y is the data to or with the upper 8 bits in X - or upper imediate
0011  0XXX XXXX XXXX    - jal   X is the address offset to pc and pc+1 is stored in ra - jump and link
0011  1XXX  XXXX XXXX    - jr   X can be anything, pc is restored by value in ra- jump register( only from ra register )
0100 XXXX YYYY ZZZZ    - shw  X is the register containing the data to write, Y is the offset, Z is the register containing the address in memory  - store 16bits in memory ( Addresses in memory can be read or written 16 bits at a time only)
0101  XXXX YYYY ZZZZ   - lhw  X is the register to store data in, Y is the offset,  Z is the register containing the memory address  - load 16bits from memory                          ( That is 0 represents first 16 bits and 1 represents next 16 bits)
0110  XXXX YYYY ZZZZ    - beq  X is the PC offset, Y and Z are registers to compare - break equal
0111  XXXX YYYY ZZZZ   - bne   X is the PC offset, Y and Z are registers to compare - break not equal

In the following, assume $ is the operation

X, Y and Z are registers, X=Y$Z

1000 XXXX YYYY ZZZZ    - and   - and gate
1001 XXXX YYYY ZZZZ    - or    - or gate
1010 XXXX YYYY ZZZZ    - add   - addition
1100 XXXX YYYY ZZZZ    - and~  - A and ~B
1101  XXXX YYYY ZZZZ   - or~   - A or ~B
1110  XXXX YYYY ZZZZ    - sub   - subtraction

if(Y<Z) X=1 else X=0

1111  XXXX YYYY ZZZZ    - stl   - set less than

To do list:

Forwarding unit - on going

Hazard detection unit - yet to start