Apakah Set Arahan

1
Apakah Set Arahan?

• Koleksi arahan yg lengkap yg difahami oleh CPU
• Kod Mesin (Machine code)
• Perduaan (Binary)
• Selalunya diwakili oleh kod2 penghimpunan
  (assembly codes)

2
Element2 Arahan

• Kod operasi (Operation code - op code).
• Buat ini (Do this).
• Sumber rujukan operan (Source operand reference).
• Ke ini (To this).
• Rujukan jawapan operan (Result operand
  reference).
• Letak jawapan di sini.
• Rujukan arahan berikut (Next instruction
  reference).
• Pabila ia selesai, buat ini pulak...

3
Pewakilan Arahan

• Dlm kod mesin, setiap arahan mempunyai pola bit
  yg unik
• Utk kemudahan manusia (yakni pengaturcara),
  pewakilan simbolik digunakan
• Cth. Add, sub, load
• Operan juga boleh diwakili dgn cara ini
• Add a,b

4
Format2 Arahan

• Paparan bit2 dlm arahan
• Termasuk opcode
• Termasuk (tersirat atau nyata) operan2
• Selalunya lbh drpd satu format arahan dlm set
  arahan.

5
Format Arahan
Arahan
4
6
6
Operand Reference 1
Operand Reference 2
Op-Code
Operand field
16 bits
6
Jenis2 Arahan

• Pemprosesan data (Data processing)
• Penyimpanan data (Data storage - memori utama)
• Pergerakkan data (Data movement- I/O)
• Program flow control

7
Panjang Arahan

• Dipengaruhi oleh dan mempengaruhi
• Saiz Memori
• Oraganisasi Memori
• Struktur bas
• Kekompleksan CPU
• Kelajuan CPU
• Keseimbangan ant powerful instruction
  repertoire saving space.

8
Number of Addresses (a)

• 3 addresses
• Operand 1, Operand 2, Result
• a b c
• May be a forth - next instruction (usually
  implicit)
• Not common
• Needs very long words to hold everything

9
Number of Addresses (b)

• 2 addresses
• One address doubles as operand and result
• a a b
• Reduces length of instruction
• Requires some extra work
• Temporary storage to hold some results

10
Number of Addresses (c)

• 1 address
• Implicit second address
• Usually a register (accumulator)
• Common on early machines

11
Number of Addresses (d)

• 0 (zero) addresses
• All addresses implicit
• Uses a stack
• e.g. push a
• push b
• add
• pop c
• c a b

12
Bilangan Alamat

• Mesin satu alamat
• Add b gt ac ac b
• Mesin dua alamat
• Sub a, b gt a a - b
• Mesin tiga alamat
• Add a, b, c gt a b c

13
Bilangan Alamat

• Arahan tiga alamat
• Arahan komen/makna
• Sub y, a, b ylt a-b
• MPY t, d, e tlt de
• Add t, t, c tlt tc
• Div y, y, t ylt y/t
• Y (a-b) / (cde)

14
Bilangan Alamat

• Arahan dua alamat
• MOV y, a ylt a
• Sub y, b ylt y-b
• MOV t, d tlt d
• MPY t, e tlt te
• Add t, c tlt tc
• Div y, t ylt y/t
• Y (a-b) / (cde)

15
Bilangan Alamat

• Arahan satu alamat
• LOD d aclt d
• MPY e aclt ace
• Add c acltacc
• STR y ylt ac
• LOD a aclt a
• Sub b aclt ac-b
• Div y aclt ac/y
• STR y ylt ac
• Y (a-b) / (cde)

16
Berapa banyak alamat?

• Lebih alamat
• Lbh komplek (powerful?) arahan
• Lbh daftar (register)
• Inter-register operations are quicker
• Sedikit arahan per program
• Sedikit alamat
• Krg komplek (powerful?) arahan
• Lbh arahan per program
• Cepat Ambil/Laksana arahan

17
Keputusan Rekabentuk (1)

• Himpunan operasi
• Berapa byk operasi?
• Apa yg blh dilakukan?
• Berapa komplek?
• Jenis2 data
• Format2 arahan
• Panjang kod operasi
• Bilangan alamat

18
Keputusan Rekabentuk (2)

• Daftar2 (Registers)
• Bil. daftar2 CPU yg ada
• Which operations can be performed on which
  registers?
• Mod Alamat (later)
• RISC v CISC

19
Jenis2 Operan

• Alamat2.
• Nombor2.
• Integer/floating point.
• Characters.
• ASCII etc.
• Data Logikal.
• Bits or flags.
• (Aside is there any difference between numbers
  and characters? Ask a C programmer!).

20
Pentium Data Types

• 8 bit byte
• 16 bit word
• 32 bit double word
• 64 bit quad word
• Addressing is by 8 bit unit
• A 32 bit double word is read at addresses
  divisible by 4

21
Specific Data Types

• General - arbitrary binary contents
• Integer - single binary value
• Ordinal - unsigned integer
• Unpacked BCD - one digit per byte
• Packed BCD - 2 BCD digits per byte
• Near pointer - 32 bit offset within segment
• Bit field
• Byte string
• Floating point

22
Jenis2 Operasi

• Perpindahan data (Data transfer)
• Aritmetik
• Logikal
• Pertukaran (Conversion)
• I/O
• Kawalan sistem (System control)
• Transfer of control

23
Perpindahan Data

• Tentukan
• Sumber (Source)
• Destinasi (Destination)
• Amount of data
• Berkemungkinan arahan yg berbeza utk permindahan
  yg berbeza
• E.G. IBM 370
• Atau satu arahan dan berlainan alamat
• E.G. VAX

24
Aritmetik

• Tambah, tolak, darab, bahagi
• Integer bertanda
• Titik apungan?
• Mungkin juga termasuk
• Increment (a)
• Decrement (a--)
• Negate (-a)

25
Shift and Rotate Operations
26
Logikal

• Bit wise operations
• And, or, not

27
Pertukaran

• Cth. Binary to decimal

28
Input/output

• Mungkin ada arahan spesifik
• Mungkin dilakukan mgunakan arahan peralihan data
  (memory mapped)
• Mungkin dilakukan oleh controller (DMA) yg
  terasing.

29
Kawalan Sistem

• Arahan terlindung
• CPU perlu berada dlm situasi tertentu
• Ring 0 on 80386
• Kernel mode
• Utk kegunaan OS

30
Permindahan Kawalan

• Cabang (Branch)
• E.G. Branch to x if result is zero
• Langkau (Skip)
• E.G. Increment and skip if zero
• ISZ register1
• Branch xxxx
• Add a
• Panggil subrutin (Subroutine call)
• C.F. Interrupt call

31
Pentium Floating Point Data Types

• See Stallings (5th Ed - Chapter 9, 6th Ed Chap
  10) / Instruction Sets Characteristics and
  Function