A does not work as B did.
A does not work as B did.
In this sentence, I am confused whether B did work or not.
Namely,
A: not work, B: work
OR
A: not work, B: not work

Which one is correct?

Question

A does not work as B did.
A does not work as B did. 
In this sentence, I am confused whether B did work or not.
Namely, 
A: not work, B: work
OR
A: not work, B: not work

Which one is correct?

Answer

If you add a comma:
A does not work, as B did.
B worked, and A does not work.

Without a comma:
A does not work as B did=A does not work in the same way as B did.
A and B both work, but the way A works is different from the way B worked.

By using past tense for B, you imply that B worked well when it was active, but for some reason it is not working now.  If you change "did" to "does", the logic becomes much simpler.

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