Magnitude Comparators

Dec 07, 2007 2 Replies

Hi,



I'm working on a school project where I need to compare 16bits (4 BCD values) from a CMOS logic system and need alternative ways of doing it.



So far I've got 4 cascaded 4063 bit comparators, ADC conversion but I'm struggling for a third. Can anyone suggest a method?



I was thinking about using a CMOS compatible 74 series bit comparator but it's not really that different from the 4063 method......



Cheers,



Michael


A microcontroller running a short loop? Some of the Atmel 8-bit microcontrollers are absurdly cheap.

Hi, Michael. You might get some homework points for variety by latching the two 16-bit numbers into shift registers, then serially comparing the bits, starting with the most significant. First non- equal (discrete logic here) sets the greater-than or less than flip- flop. which locks the other one out. Both flip flops reset on the latch signal.

If it were an 8 X 8 or even a 12 X 12 compare you could use one PROM. You might offer a suggestion that you could compare the first byte using a PROM, then if equal, compare the second byte using the same PROM or a second PROM if you want to stay away from latching and sequential logic.

Someone else has mentioned using a PIC, which is a valid one-chip solution.

Not too many ways to compare two numbers except to compare them, I guess.

Good luck Chris

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