Design a simple microcomputer for 8-bit signed binary numbers. use a keypad for data entry and a 256 x 8 ram memory. the microcomputer should have the following 8-bit registers: a (accumulator), b (multiplier), mdr (memory data register), pc (program counter), and mar (memory address register). the ir (instruction register) can have up-to 8-bits. the b register is connected to the a register so that a and b can be shifted together during multiplication. only one 8-bit adder and one complementer are allowed. the microcomputer should have a 256-word-by-8-bit memory for storing instructions and data. it should have two modes: (a) memory load and (b) execute program. use a dip switch to select the mode. memory load mode operates as follows: select mode = 0 and reset the system. then press one key (hex) on the keypad followed by pushing a button to load each word in memory. the first word is loaded at address 0, the second word an address 1, etc. execution mode operates as follows: select mode = 1 and press reset. execution begins with the instruction at address 0. each instruction will be one or two words long. the first word will be the op-code, and the other (if any) will be an 8-bit memory address or immediate operand. one bit in the op-code should distinguish between memory address and immediate operand mode. 2’s complement is used to represent negative numbers. implement the following instructions