ST Instruction

The ST instruction allows storing of values at specific addresses

Stores a register into memory

ST

The ST instruction stores a given register's value in an address relative to the current program counter + the given offset.

0011 SR1 FFFFFFFFF

Input

• 0011
  • The ST opcode
• SR1
  • Source Register who's value is going to be copied to an address
• FFFFFFFFF
  • Offset based on Program Counter + Offset, where the value will be stored at.

Example:

0011 000 000000011

This will take the value stored at R0, and store the value at the address that is 1 + 0000 0001 1

Which is (1 + 2) addresses away from the ST command.

STR

The STR instruction stores the value of a given input at the base address of a given register's value + the offset given

0111 SR1 RRR FFFFFF

Input

• 0111
  • The STR opcode
• SR1
  • Source of register's value which we are copying to an address
• RRR
  • Base Register, Use it's value + offset to calculate address to which we are storing the value
• FFFFFF
  • Offset, used to calculate destination base + offset

Example:

0111 000 001 000001

This line will get the value stored at R0, Get the value at R1, Add R1's value to the offset(000001 = 1), and store the value at that given address.

Let's say R1's value = x4000(hex) or in binary 0100 0000 0000 0000 (binary) and our offset is still 000001 so it'd be x4000 + 1 = x4001. Therefore, the value stored at R0 will be stored at address x4001