Hello everyone,

I have a question where I need to write which value D3,D2,D1,D0 will have for all possibilities of A3, A2, A1, A0.

Here is the image:

This question seems very straightfoward. I just have to check A2 to see which ROM will be enable, then I check the address (A3,A1,A0) then I check what will be in D3,...,D0.

My question is: what is that "A▼"? And what is that "} A 0/7"? and in what order is the output? is the MSB the one in "A▼"?

PS: Sorry for my english.

 

Hello,

Have a look at the following PDF's:
www.ddpp.com/DDPP3_pdf/IEEEsyms.pdf
www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf (page 20)

Bertus

 

Well, so correct me if I'm wrong:

-> The block on top is a common control block, meaning that it ENABLE signal control all bottom block
-> The ▼ means Three-State what means that if the block isn't enabled, it will be in high impedance, removing the output of the circuit.
->" } A 0/7 " only means grouping the bits meaning that the input group is, in case of binary, a number that you will convert to get the correspondent output.

But I still have one thing to confirm: let me say I have input 0000. Then ROM A will be active, then output will be 0111. But in the output where will be the MSB bit? is is the most bottom one (going to D3)?