Hex   Binary    Decimal   Octal
---   ------    -------   -----
 0         0          0       0
 1         1          1       1
 2                    2       2
 3                    3       3
 4                    4       4
 5                    5       5
 6                    6       6
 7                    7       7
 8                    8
 9                    9
 A
 B
 C
 D
 E
 F

Hex to Binary table
====================
Hex     Binary
---     ------
 0        0000
 1        0001 
 2        0010
 3        0011 
 4        0100
 5        0101 
 6        0110
 7        0111
 8        1000
 9        1001
 A        1010
 B        1011
 C        1100
 D        1101
 E        1110
 F        1111

///////////////////////////////////////////////////////
Take the hex no. ABBA and convert it to binary.

A-->      1010
B-->      1011
B-->      1011
A-->      1010

1010 1011 1011 1010

1010101110111010 (BASE 2/BINARY) = ABBA (BASE 16/HEX.)
///////////////////////////////////////////////////////

Take the hex no. 0000 and convert it to binary.
(using the technique we have just used)

0000 (BASE 16/HEX) = 0000 0000 0000 0000 (BASE 2/BINARY)

Take the hex no. 0200 and convert it to binary.
0200 (BASE 16/HEX) = 0000 0010 0000 0000 (BASE 2/BINARY)

///////////////////////////////////////////////////////

AX 	16 BITS LONG 
BX	     "
CX           "
DX           "

AX could contain anything in the range
0000 0000 0000 0000 up to 1111 1111 1111 1111

We can refer to two different parts of AX - AH (HIGH PART OF AX)
                                          - AL (LOW PART OF AX)

AX - AH (HIGH) AL (LOW PART)
BX - BH (HIGH) BL (LOW PART)
CX - CH (HIGH) CL (LOW PART)
DX - DH (HIGH) DL (LOW PART)

The first instruction was 
	mov ah, 02h

Initially AX Contained What (in binary) ?  0000 0000 0000 0000

The first instruction : mov ah,02h affects which part of the register?
The high part?

Which part is the high part? 
0000 0000 0000 0000
<-------> <------->
First 8     Last 8

Answer:   First 8

//////////////////////////

After the instruction 
mov ah,02h has been executed?

What is contained in the register AX?
Write your answer down as both a binary number AND a hex. number.

Hint: For you binary you will have a 16 bit number
      For your hex you will have a 4 digit number e.g.

Binary: 0000 0000 0000 0000
Hex:    0000

Answer is.....


Binary  0000 0010 0000 0000
Hex:    0200 

(1st instruction executed )

//////////////////////////
After the 2nd instruction has been executed?
mov dl,041h  

Which register is affected here? AX, BX CX, OR DX?
The D tells us its DX. The L tells us its the LOW PART of DX.

What is contained in the register DX?
Write your answer down as both a binary number AND a hex. number.

You can ignore the zero (041h).... 41h (41 in hex.)


Binary: 0000 0000 0100 0001
Hex:    0041
 

//////////////////////////
The next instruction is 
int 21h 
(We will ignore this until next week).

//////////////////////////
The next instruction is 

mov ax,4c00h

Which register is affected here? Obviously AX.

What is contained in the register AX?
Write your answer down as both a binary number AND a hex. number.

Binary: 0100 1100 0000 0000
Hex:    4C00