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 => ac = ac + b • Mesin dua alamat • Sub a, b => a = a - b • Mesin tiga alamat • Add a, b, c => a = b + c

13. Bilangan Alamat • Arahan tiga alamat • Arahan komen/makna • Sub y, a, b y<= a-b • MPY t, d, e t<= d*e • Add t, t, c t<= t+c • Div y, y, t y<= y/t • Y= (a-b) / (c+d*e)

14. Bilangan Alamat • Arahan dua alamat • MOV y, a y<= a • Sub y, b y<= y-b • MOV t, d t<= d • MPY t, e t<= t*e • Add t, c t<= t+c • Div y, t y<= y/t • Y= (a-b) / (c+d*e)

15. Bilangan Alamat • Arahan satu alamat • LOD d ac<= d • MPY e ac<= ac*e • Add c ac<=ac+c • STR y y<= ac • LOD a ac<= a • Sub b ac<= ac-b • Div y ac<= ac/y • STR y y<= ac • Y= (a-b) / (c+d*e)

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 m’gunakan 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