addressing modes

Question

A certain machine uses expanding opcode. It has 16-bit instructions and 6-bit addresses. It supports one address and two address instructions only. If there are ‘n’ two address instructions, the maximum number of one address instruction is
(a) 2^16 – n          (b) 2^10 – n
(c) (2^4 – n) × 2^6     (d) 2^10

Comments

option c)...(2⁴-n)*2⁶

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here it  is asking maximum no of 1 address instruction so we have to assume  that 2 address instruction will be 1 and so maximum no of 1 instruction that can be possible will be (16-1)*2^6??
am i wrong?

Answer 1

Answer is option(c), i.e., (2⁴-n)*2⁶

For explanation, check this: https://gateoverflow.in/16361/number-address-instruction-when-address-instruction-given

Answer 2

here it  is asking maximum no of 1 address instruction so we have to assume  that 2 address instruction will be 1
and so
maximum no of 1 instruction that can be possible will be (16-1)*2^6=960