Please refer to this table of op codes for problems 21 through 23 Opcode Definition 0 Halt 2 SUBTRACT 5 LOAD ADD 3 STORE 6 BRANCH UNCONDITIONALLY 7 BRANCH ON ZERO BRANCH ON POSITIVE INPUT 901 902 OUTPUT Please refer to this table of Mailboxes and Contents for problems 21 through 23 Mailbox Contents 00 505 01 02 507 03 902 04 000 05 06 07 6 DAT 106 DAT DAT 21) What is the value in the calculator after the first instruction (505) is completed? a) 1 b) 2 c) 3 d) 6 22) What is the value in the program counter (instruction location counter) after the first instruction (505) is completed? a) 01 b) 02 c) 03 d) 04 23) What is the value in the calculator after the second (106) instruction is completed? a) 1 b)2 c) 3 d) 4 24) The leftmost bit in an IEEE standard floating point number represents a) the exponent. b) the mantissa. c) the sign of the mantissa. d) the sign of the exponent