By using this formula the largeset adder will be 7 bit full adder that can fit in Gal22v10 because the maximum number of pins are 22. Am I right?how many macro cells did your 4 bit device use?
how many i/o pins did your 4 bit device use?
how many macro cells and i/o pins not used?
for an n bits adder:
n + 1 pins for output
2n pins for input
hence total pins used is n + 1 + 2n and maximum number of pins available is 22.
how many bits of adder does that lead to?
do you have enough macro cells for that number of bits?
If we want to figure out what the largest full adder that can fit in GAL22v10, we need to consider 10macrocells as well. Right? so, it means that there are a maximum of 32 pin numbers. Am I correct?@FvM:
in a 22V10, there are 10 macrocells, with varying numbers of product terms
2 macrocells have 8 product terms, 2 have 10, 2 have 12, 2 have 14, and 2 have 16.
i believe the sum output ORs together 4 product terms and the CarryOut output ORs together 4 product terms
since the OP is building a ripple adder, and does not appear to do look ahead
@mina
the 22 i/o allows 7 bits, as you said.
the other question - there are 10 macrocells
how many did you use for the 4 bit adder?
each bit requires a SUM output and a CARRYOUT output
another aspect of the problem:
is this a stand alone device, or is it designed for extendability?
that is, can two or three of these be put in series to add larger numbers (numbers with more bits?)
if so, then each bit needs a carry in, number A in, number B in, sum output and a carry output
which means that one of the i/o has to be used for carry in, and one i/o has to be used for carry out.
that means there are only 20 i/o available for the input number and the output number.
@FvM
exactly
but the goal was for Mina to figure it out, since it seems like a homework problem
Yes, It was a part of the experience that we did two weeks ago.I could not figure this part out.
I got it. It only supports less than 10 macro cells. so a 5 bit full adder is the largest one. Thank you.32 pin numbers?
the 22V10 only has 24 pins. 2 for power and ground so 22 i/o pins
if you mean 5 bits, 00000 base 2 to 11111 base 2, or 0 to 31, for 32 numbers, yes
if you mean something else, i didn't get it
but you should think about the questions that were asked :
how many macro cells did you use for the 4 bit adder?
since the 22V10 has 10 macro cells, how many bits can it support?
What a professional designer does.. instead of being unsure: he looks into the datasheet.so, it means that there are a maximum of 32 pin numbers. Am I correct?
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