Solution%20to%20Exercise%208

1
Solution to Exercise 8
2
The algorithm

• I 0 Op ? Decode_Op(TerminalInput)I 1
  Dest ? Decode_Dest(TerminalInput)I 2 Dig1 ?
  Decode_Digit(TerminalInput)I 3 Dig2 ?
  Decode_Digit(TerminalInput)
• If Op e E ? 0
• Tmp ?TerminalInput, I I1
• (I 3) Tmp 20h (space)
• RegDest ? Op(RegDest,Dig1)
• I 0
• (I4)
• RegDest ? Op(Dig1,Dig2)
• I 0

3
The algorithm

• I 0 Op ? Decode_Op(TerminalInput)I 1
  Dest ? Decode_Dest(TerminalInput)I 2 Dig1 ?
  Decode_Digit(TerminalInput)I 3 Dig2 ?
  Decode_Digit(TerminalInput)
• If Op e E ? 0
• Tmp ?TerminalInput, I I1
• (I 3) Tmp 20h (space)
• RegDest ? Op(RegDest,Dig1)
• I 0
• (I4)
• RegDest ? Op(Dig1,Dig2)
• I 0

Execute ifCondition
4
The algorithm

• I 0 Op ? Decode_Op(TerminalInput)I 1
  Dest ? Decode_Dest(TerminalInput)I 2 Dig1 ?
  Decode_Digit(TerminalInput)I 3 Dig2 ?
  Decode_Digit(TerminalInput)
• If Op e E ? 0
• Tmp ?TerminalInput, I I1
• (I 3) Tmp 20h (space)
• RegDest ? Op(RegDest,Dig1)
• I 0
• (I4)
• RegDest ? Op(Dig1,Dig2)
• I 0

Put resultin the reg Written in dest
5
Register sizes

• Op 2 bit
• Dest 2 bit
• Dig1 8 bits
• Dig2 8 bits
• a to d 8 bits
• Tmp 8 bits
• E 1

6
Cond2
Cond1
7
Control of the circuit

• NextChar
• Decode1Enable
• Decode2Enable
• Mux2
• Mux3
• Iwrite
• Tmpwrite

8
The control of the circuit
Input
Output
E Step Cond1 Cond2 nxtchar decode1enable decode2enable MUX2 MUX3 Iwrite tmpwrite
1 0 0 0 1 1 0 0 0 0 0
1 1 0 0 0 0 0 0 0 0 0
1 2 0 0 1 0 0 0 0 1 1
1 3 1 0 0 0 1 1 0 0 0
1 3 0 1 0 0 1 0 1 0 0
9
Op_Decode
Input Output
01100001(61h a) 00
01110011(73h s) 01
01100101(65h e) 11
10
Dest_Decode
Input Output
01100001(61h a) 00
01110010(62h b) 01
01100011(63h c) 10
01100100(64h d) 11