Learn English – Robbed off vs Robbed of

I don't believe you can insert a gapping comma there for two reasons.

1. Because it puts and wiring into parenthesis.

   That is, your second example can be read as

   Memory can be implemented by delays by various walls to guide the one extra bit per site needed to represent the walls.

   I don't think that's right.

2. Because the first comma could be read as a sort of Oxford comma:

   Memory can be implemented by delays and wiring, by various walls to guide the one extra bit per site needed to represent the walls.

   That doesn't look right either.

Not every omission needs a gapping comma, and there are some instances as here where adding one is a hindrance to understanding.

The comma after “job” tells us that the phrase as directed is non-restrictive.

The sentence states “you have been directed to do a job”, and implies that how you do it is up to you.

But if we take out the comma,

Complete the job as directed.

Now “as directed” is restrictive, and the sentence is saying something more severe: Do the work, and make sure you do it the way you were told to do it.