# ROM Output order

Suppose that the input is 0000. Then ROM A is Enabled, and the output will be 0111. But what will be the order of the output? Will 0 be on D0, 1 on D1, 1 on D2, 1 on D3 or 1 be in D0, 1 in D1, 1 in D2, 0 in D3?

I mean where is the MSB in the output going?

• This is inadequately specified. There is no way to tell what A3 is. Or are the D0 - D3 lines tied to the A0 - A3 lines? – WhatRoughBeast May 3 '14 at 21:56

That depends on the rom used, it should be written in the datasheet. I'd say that $D_0$ is the LSB and $D_3$ is the MSB, but that's just a guess based on the fact that $D_0$ represents $2^0$, $D_1$ represents $2^1$ and so on.
1. The '0' in D0 may represent the '0' in $2^0$.