Please send the answers to my email. Mirre06@hotmail.com Someone sent me wrong answers so please send me correct answers thanks. 1) What is a register? Be precise. Name at least two components in the LMC that meet the qualications for a register. Name several different kinds of values that a register might hold. Suppose that the following instructions are found at the given locations in memory: 20 LDA 50 21 ADD 51 50 724 51 006 a. Show the contents of the IR, the PC, the MAR, the MDR, and A at the conclusion of instruction 20. b. Show the contents of each register as each step of the fetch–execute cycle is performed for instruction 21. 3) what is the purpose of the instructions register? What takes the place of the instruction register in the LMC? 4) What is the explanation for the reasons why programmed IO does not work very well when the IO device is a hard disk or a graphics display? 5) the x86 series is an example of a CPU architecture. as you are probably aware there are a number of different chip including the x86 architecture? What word defines the difference between the various CPUs that share the same architecture? Name at least one different CPU architecture 20 LDA 50 21 ADD 51 50 724 51 006 Solution 1)The Little Man Computer (LMC) is an instructional model of a computer, created by Dr. Stuart Madnick in 1965.The LMC is generally used to teach students, because it models a simple von Neumann architecture computer - which has all of the basic features of a modern computer. It can be programmed in machine code (albeit in decimal rather than binary) or assembly code. Register: In a computer, a register is one of a small set of data holding places that are part of a computer processor . A register may hold a computer instruction , a storage address, or any kind of data (such as a bit sequence or individual characters). Some instructions specify registers as part of the instruction. For example, an instruction may specify that the contents of two defined registers be added together and then placed in a specified register. A register must be large enough to hold an instruction - for example, in a 32-bit instruction computer, a register must be 32 bits in length. In some computer designs, there are smaller registers - for example, half-registers - for shorter instructions. Depending on the processor design and language rules, registers may be numbered or have arbitrary names. Small, permanent storage locations within the CPU used for a particular purpose Manipulated directly by the Control Unit Wired for specific function Size in bits or bytes (not in MB like memory) Can hold data, an address or an instruction Use of Registers Scratchpad for currently executing program Holds data needed quickly or frequently Stores information about status of CPU and currently executing program Address of next program instruction Signals from external devices General Purpose Registers User-visible registers Hold intermediate results or data values, e.g., l.

1. Please send the answers to my email. Mirre06@hotmail.com
Someone sent me wrong answers so please send me correct answers thanks.
1) What is a register? Be precise. Name at least two components in the LMC that meet the
qualications for a register. Name several different kinds of values that a register might hold.
Suppose that the following instructions are found at the given locations in memory:
20
LDA
50
21
ADD
51
50
724
51
006
a. Show the contents of the IR, the PC, the MAR, the MDR, and A at the conclusion of
instruction 20.
b. Show the contents of each register as each step of the fetch–execute cycle is performed for
instruction 21.
3) what is the purpose of the instructions register? What takes the place of the instruction
register in the LMC?
4) What is the explanation for the reasons why programmed IO does not work very well when
the IO device is a hard disk or a graphics display?
5) the x86 series is an example of a CPU architecture. as you are probably aware there are a
number of different chip including the x86 architecture? What word defines the difference
between the various CPUs that share the same architecture? Name at least one different CPU
architecture
20
LDA

2. 50
21
ADD
51
50
724
51
006
Solution
1)The Little Man Computer (LMC) is an instructional model of a computer, created by Dr. Stuart
Madnick in 1965.The LMC is generally used to teach students, because it models a simple von
Neumann architecture computer - which has all of the basic features of a modern computer. It
can be programmed in machine code (albeit in decimal rather than binary) or assembly code.
Register:
In a computer, a register is one of a small set of data holding places that are part of a computer
processor . A register may hold a computer instruction , a storage address, or any kind of data
(such as a bit sequence or individual characters). Some instructions specify registers as part of
the instruction. For example, an instruction may specify that the contents of two defined registers
be added together and then placed in a specified register. A register must be large enough to hold
an instruction - for example, in a 32-bit instruction computer, a register must be 32 bits in length.
In some computer designs, there are smaller registers - for example, half-registers - for shorter
instructions. Depending on the processor design and language rules, registers may be numbered
or have arbitrary names.
Small, permanent storage locations within the CPU used for a particular purpose
Manipulated directly by the Control Unit
Wired for specific function
Size in bits or bytes (not in MB like memory)
Can hold data, an address or an instruction
Use of Registers
Scratchpad for currently executing program
Holds data needed quickly or frequently
Stores information about status of CPU and currently executing program
Address of next program instruction
Signals from external devices

3. General Purpose Registers
User-visible registers
Hold intermediate results or data values, e.g., loop counters
Equivalent to LMC’s calculator
Typically several dozen in current CPUs
Special-Purpose Registers
Program Count Register (PC)
Also called instruction pointer
2.Instruction Register (IR)
Stores instruction fetched from memory
3. Memory Address Register (MAR)
4.Memory Data Register (MDR)
5. Status Registers
Status of CPU and currently executing program
Flags (one bit Boolean variable) to track condition like arithmetic carry and overflow,
power failure, internal computer error
The control unit contains several important registers.
As already noted, the program counter register holds the address of the current instruction being
executed.
The instruction register (IR) holds the actual instruction being executed currently by the
computer. In the Little Man Computer this register was not used; the Little Man himself
remembered the instruction he was executing. In a sense, his brain served the function of the
instruction register.
The memory address register (MAR) holds the address of a memory location.
The memory data register (MDR), sometimes known as the memory buffer register, will hold a
data value that is being stored to or retrieved from the memory location currently addressed by
the memory address register.
The LMC model is based on the concept of a little man shut in a closed mail room (analogous to
a computer in this scenario). At one end of the room, there are 100 mailboxes (memory),
numbered 0 to 99, that can each contain a 3 digit instruction or data (ranging from 000 to 999).
Furthermore, there are two mailboxes at the other end labeled INBOXand OUTBOX which are
used for receiving and outputting data. In the center of the room, there is a work area containing
a simple two function (addition and subtraction) calculator known as the Accumulator and a
resettable counter known as the Program Counter. The Program Counter holds the address of the
next instruction the Little Man will carry out. This Program Counter is normally incremented by
1 after each instruction is executed, allowing the Little Man to work through a program

4. sequentially. Branchinstructions allow iteration (loops) and conditional programming structures
to be incorporated into a program. The latter is achieved by setting the Program Counter to a
non-sequential memory address if a particular condition is met (typically the value stored in the
accumulator being zero or positive
3)The Instruction Register (IR) stores the instruction currently being executed. In simple
processors each instruction to be executed is loaded into the instruction register which holds it
while it is decoded, prepared and ultimately executed.BRANCH (unconditional), BRANCH IF
ZERO (conditional) takes the place of the instruction register in the LMC