Microoperation
Fundamental operation on data stored in registers that can be performed in one clock pulse
What are the four categories of microoperations?
- Data transfer
- Arithmetic
- Logical
- Shift
What does the following mean in data transfer notation: C: R2 <— R1
Load from Register 1 into Register 2
How to build an n-bit. one directional data bus using multiplexers
registers into MUX and out to another register
Know the rules for number and size of multiplexers
- Sign of MUX is determined by the # of registers
- # of MUX is determined by # of bits per register
What is the tri-state output
three outputs: 0 , 1 , high-impedence (Z)
How to build an n-bit one directional data bus using tri-state buffers
2x4 decoder, each output into data line A-D with inverters sticking out. All then connect back to A line
Memory read as a microoperation
R <– M [Ad]
How to build a simple 4-bit adder circuit (figure 4-6)
full adders connected through carry in/outs
How to build a simple 4-bit adder-subtractor (figure 4.7)
full adders from right to left connected through carry in/outs. A input normal but B input is B and M passed in XOR gate.
What property of an exclusive-OR gate did we discuss that allows for either addition or subtraction in figure 4-7
if m = 0, B gets through
if m = 1 , B’ gets through
Be able to add or subract two binary numbers
subtract: 2s complement
take the two’s complement of a binary number
inverse and add 1
Know how to build a Logic unit that performs several logical operations (figure 4-10)
4x1 MUX with each operation function in each input. Ex 0 = AND 1 = OR, etc.
Selective-set
if control = 1, A = 1
Selective-complement
If control = 1, A = A’
Selective-clear
If control = 1, A = 0
Mask
If control = 1, A stays same, otherwise A = 0
Logical Shift microoperations
transfer 0 into serial in
Circular shift microoperations
circulate bits of register around two ends without loss of information
What was the goal in Lab 6?
to add two 2-bit numbers together
What chip did we use in Lab 6?
7483 4-bit adder chip
What did we have to do with the carry-input to the 4-bit adder in Lab 6?
set it to 1
How many bits do we add together in Lab 6?
2 bit originally, 4 bit extra credit
