Understanding ROM Implementation with Examples and Truth Tables

[transgalactic]

http://img211.imageshack.us/my.php?image=img86301qt1.jpg

i have a trouble in understanding ROM
i know that it has addresses and words and that its used in computers in order
to store info.

but when i get to the example i can't understand the functionality of it.

in the example that i present here we have a truth table and then
the Rom implementation
i don't have any problem to build a KARNO table
and to build a big circuit out of it

but i need to implement ROM here

 

[wildman]

What don't you understand? This is very simple.

A ROM is just an array of cells that can be set to one or zero. The array is accessed (in your case) six cell at a time. This can be thought of as a bit vector. This bit vector is then accesses via an address which (in your case) is three input lines. If you input 000 on the address lines, you get the first vector, 001 the second vector etc. This vectors are used for whatever you want -- it is often a computer program or a look up table.

To do your problem, just stick the values you want into the appropriate bit vector in order...

 

[transgalactic]

i noticed that they just put a big box on a certain part of karno table
and call it ROM
the leave out two lines because they can predict there out put
http://img410.imageshack.us/my.php?image=img86301qt1ka1.jpg

i could make a ROM out of the whole thing

am i correct?