I'm sitting an exam on Computer Architecture in a few days and i'm stuck on a particular type of question.

I'm asked to:

Provide a detailed schematic for a functional unti that implements the following micro-operations

enter image description here

Any help would be great even just a nudge in the right direction.

  • 2
    $\begingroup$ Some of the FS bits are going to control several muxes that will mux between the adder, an "and", an "or", an "xor", the "not" and the shifters. You're going to need to be able to control the carry-in of the adder, and you'll need to be able to negate the B input. Then it's "just" a matter of mapping the FS bits to the mux inputs, to the carry-in, to the B negater and to the shifteer. Note that they've tried to make it slightly easier by making the left two bits of FS determine whether you are using the adder, shifter or "logic" unit. $\endgroup$ – Wandering Logic Aug 23 '13 at 22:57
  • 1
    $\begingroup$ @WanderingLogic The encoding also has the nice feature that for the FS=00xxx, bit 0 (least significant) is the carry-in, bit 2 determines whether the second operand is inverted, and bit 2 XOR bit 1 determines whether the second operand is 0 or B. (Note: A-1 = A + NOT(0) and A = A + NOT(0)+1) [I thought I left a comment with this information earlier, but perhaps I did not actually submit the comment.] $\endgroup$ – Paul A. Clayton Aug 24 '13 at 3:20
  • $\begingroup$ Doh! The question was asked on Stack Overflow and I left my comment there. Sigh--time for bed! $\endgroup$ – Paul A. Clayton Aug 24 '13 at 3:40
  • $\begingroup$ thanks guys does anybody know where I could get a sample schematic, not the answer just something similar? $\endgroup$ – matthiasgh Aug 24 '13 at 18:55
  • $\begingroup$ As a general rule, we don't like to just answer homework or exam problems because we don't think that helps you. Please share with us what you have tried so we can identify and address your problems. (Also, please get rid of the horrible image and typeset the values properly.) $\endgroup$ – Raphael Aug 26 '13 at 7:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.