Learning Objectives

  • Understand data represenatation ( ASCII and UNICODE)
  • Explain memory hierarchy, memory organization, memory storage devices and cache memory
  • User Check
    All students can draw block diagram of the Von Nuemann model 
  • User Check
    Understand Instruction execution through instruction cycles and also interrupt handling

Teacher show that 8 bits can represtent 256 things... ( 255 highest number, but if all zero then can repreneset 256 ( 2 powe 8 ) ASCII stands for American Standard Code for Information Interchange

Learning Objectives

  • Understand Boolean operators : AND, OR, NOT, NAND, NOR and XOR
  • Able to construct simple truth tables with no more than 3 inputs 
  • User Check
    Construct logic diagrams based on no more than 3 inputs 

Homework click here (  ) 


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Conditional statements and logic operators practice  ( Computational thinking )

Absolute will return the absolut value example abs(-21)  will return 21

Fetch - Decode - Execute - Store Cycle

My resources click here

Link to Little Man Computer Click Here 

Type in these example instructions to that will add 2 numbers:    INP, STA 99, INP, ADD  99, OUT, HLT

The instructions are held in RAM / Memory

The instruction register holds the instruction code  exampe 3 to store  the address regsiter holds the address to store what is held in the accumulator.

Here is the code to subtract 2 numbers , try it out

INP 
STA A 
INP 
STA B 
LDA A 
SUB B 
OUT 
HLT
A    DAT
B    DAT

Little Man Computer references

Numeric code

Mnemonic code

Instruction

Description

1xx

ADD

ADD

Add the value stored in mailbox xx to whatever value is currently on the accumulator (calculator).

Note: the contents of the mailbox are not changed, and the actions of the accumulator (calculator) are not defined for add instructions that cause sums larger than 3 digits.

2xx

SUB

SUBTRACT

Subtract the value stored in mailbox xx from whatever value is currently on the accumulator (calculator).

Note: the contents of the mailbox are not changed, and the actions of the accumulator are not defined for subtract instructions that cause negative results - however, a negative flag will be set so that 8xx (BRP) can be used properly.

3xx

STA

STORE

Store the contents of the accumulator in mailbox xx (destructive).

Note: the contents of the accumulator (calculator) are not changed (non-destructive), but contents of mailbox are replaced regardless of what was in there (destructive)

5xx

LDA

LOAD

Load the value from mailbox xx (non-destructive) and enter it in the accumulator (destructive).

6xx

BRA

BRANCH(unconditional)

Set the program counter to the given address (value xx). That is, value xx will be the next instruction executed.

7xx

BRZ

BRANCH IF ZERO (conditional)

If the accumulator (calculator) contains the value 000, set the program counter to the value xx. Otherwise, do nothing.

Note: since the program is stored in memory, data and program instructions all have the same address/location format.

8xx

BRP

BRANCH IF POSITIVE (conditional)

If the accumulator (calculator) is 0 or positive, set the program counter to the value xx. Otherwise, do nothing.

Note: since the program is stored in memory, data and program instructions all have the same address/location format.

901

INP

INPUT

Go to the INBOX, fetch the value from the user, and put it in the accumulator (calculator)

Note: this will overwrite whatever value was in the accumulator (destructive)

902

OUT

OUTPUT

Copy the value from the accumulator (calculator) to the OUTBOX.

Note: the contents of the accumulator are not changed (non-destructive).

0

HLT

HALT

Stop working.

DAT

DATA

This is an assembler instruction which simply loads the value into the next available mailbox. DAT can also be used in conjunction with labels to declare variables. For example, DAT 984 will store the value 984 into a mailbox.