INTERNAL MEMORY

INTERNAL MEMORY.

Secara asas memori terbahagi kepada :

·         Memori fizikal

·         Memori virtual

·         Caches

Operasi kepada cell memori ada dua iaitu write and read.

Dia mempunyai 2 terminal iaitu:

1.      Select terminal – untuk membuat pilihan sama ada cell memori perlu baca atau pun menulis.

2.      Terminal pengawalan – to indicate read/write.

SEMIKONDUKTOR MEMORI.

·         RAM (RANDOM ACCESS MEMORY)

o   Boleh baca / tulis.

o   Volatile

o   Simpanan sementara.

o   Terbahagi kepada dua static atau dinamik.

Static RAM.

Menggunakan banyak transistor, selalunya 4-6 setiap satu cell memori tapi tak ada kapasitor dalam setiap cell.Selalunya SRAM digunakan untuk cache.

Dynamic RAM

Ada cell memori menggunakan transistor dan kapasitor.

Dynamic RAM

·         Memori utama.

·         Tidak mahal.

·         Perlahan

·         Need refresh circuits

·         Smaller per bits

·         Essentially analogue

o   Setiap level berdasarkan nilainya.

·         Simpler constraction

·         Charges leak

·         Bits stored as charge in capacitors.

DRAM OPERATION.

·         Address line (dalam i/o module) aktif apabila bit dibaca atau ditulis.

o   Transistor ditutup(cuurent flows)

·         Tulis(write)

o   Voltage to bit line

§  Nilai 1 tinggi , 0  yang rendah.

o   Signal untuk address line

§  Transsferrs charge to capacitor.

·         Baca(read)

o   Address line dpilih.

§  Transistor dibuka.

o   Charge from capacitor fed via bit line to sense amplifier

§  Bandingkan menggunakan rujukan nilai 0 atau 1.

o   Cas kapasitor harus disimpan.

Static RAM

·         Bit disimpan sama ada buka atau tutup suis tersebut.

·         No charges to leak

·         No refreshing needed when powered

·         More complex construction

·         Setiap satu bit besar

·         Lebih mahal

·         Does not need refresh circuits

·         Cepat

·         Cache

·         Digital

o   Menggunakan flip-flop.

STATIC RAM OPERATION.

·         Transistor arrangement gives stable logic state

·         State 1

o   C₁ high, C₂ low

o   T₁ T₄off, T₂ T₃on

·         State 0

o   C₁ low, C₂ high

o   T₁ T₄on, T₂ T₃off.

·         Address line transistors T₅ T₆ is switch.

·         Write – apply value to B and compliment to B.

·         Read – value is on line B.

SRAM vs DRAM.

·         Kedua-duanya volatile.

o   Kuasa diperlukan untuk keluarkan data.

·         Dynamic cell

o   Senang untuk dibina, dan kecil.

o   More dense

o   Kurang mahal

o   Needs refresh

o   Memori unit yang besar.

·         Static

o   Cepat

o   Cache

READ ONLY MEMORY(ROM)

·         Juga dikenali sebagai firmware.

·         ROM bukan sahaja digunakan didalam computer malahan kebanyakkan barangan elektronik juga.

·         Merupakan simpanan tetep

o   Non-volatile

·         Microprogramming

·         Subrutin library

·         Program system(BIOS)

·         Function tables

JENIS – JENIS ROM.

·         Menulis apabila dibuat

o   Sangat mahal untuk yang kecil.

·         Programmable (once)

o   PROM

o   Need special equipment to program

·         Read “mostly”

o   Erasable Programmable (EPROM)

§  Dipadam menggunakan UV

o   Electrically Erasable (EEPROM)

§  Mengambil masa yang lama untukmenulis berbanding membaca.

o   Flash memory

§  Memadam seluruh elektrik memori.

Error Correction

·         Hard failure

o   Permanent defect

·         Soft error

o   Random, non-destructive

o   Tiada kerosakan kekal kepada memori.

·         Dapat mengesan Hamming error menggunakan kod pembetulan.

                                                                                                                      -NURUL AIN FARHANA-

INPUT AND OUTPUT ARCHITECTURE

INTPUT AND OUTPUT ARCHITECTURE.

INPUT DEVICES

·         Papan kekunci

·         Tetikus

·         Scanner

·         CD-ROM

·         Pengawalan (controller)

OUTPUT DEVICES

·         Monitor

·         Printer

·         Disk drives

·         Floppy disk

·         CD RW-ROM

·         Speakers

Input - hantar arahan kepada CPU.

Output – terima arahan daripada CPU.

I/O devives can bee characterized by:

Behaviour : input , output , storage.

Partner : human or machine

Data rate: bytes/sec, transfers/sec.

I/O devives can bee characterized by:

·         How the component (controller, memory, processor) can be communicated each others by using bus system.

·         All component have their own bus system.

·         Graphics output – monitor.

·         Network -  LAN network.

I/O module:

·         Interface to CPU and memory.

·         Interface to one or more peripherals

·         Example : printer

Have their own interface I/O module.

Controller and timing

1.       CPU asks I/O module to check the status of attached devices.

2.       I/O module tells the status.

3.       CPU request for data transfer to I/O module if devices is ready.

4.       I/O module gather the data and transfer to the CPU.

Example : pen  drive - we put the new devices in our computer.

                  : printer -  if we would like to print something.

CPU Communication.

1.       Command decoding

·         Tulis(write) and baca (read)

2.       Devices communication

·         Involves command , status communcations.

3.       Data buffering

·         Proses ditangguhkan / kita kena tunggu sampai buffer tersebut telah bersedia.

·         Essential function to overcome speed mismaten.

·         Contoh : you tube – kita kena tunggu juga walaupun kita dah tekan butang mainkan.

: printer -  kitanak print nota, printer tutakterus print nota tu sebab dia nak baca dulu data kita baru dia akan print seperti yang diminta.

4.       Error detection

·         Paper jam or stunk , bad data etc.

·         Contoh :printer - kita nak print nota tapi kertas sudah habis jadi dia akan keluarkan pop up di skrin komputer untuk bagi tahu kita yang kertas tiada.

I/O system characteristics

·         kebergantungan sangat penting

§  selalunya apabila kita naks impan devices

·         mengukur setiap persembahannya.

§  Latency (tindakbalas terhadap masa melalui desktop dan embedded)

INTERCONNECTING COMPNENT

Ø  Need interconnecting between CPU, memory, I/O controller.

Ø  Bus : share communication channel

o   Can became a bottleneck.

Ø  Performance limited by physical factors

o   Wire length, number of connections

Ø  More recent alternative : high-speed serial connections with switches.

o   Like network.

I/O MANAGEMENT

·         I/O is mediated by the operating system.

§  Multiples program shared I/O resources.

Ø  Need protection and scheduling.

§  I/O causes synchronous interrupts.

Ø  Same machine as exceptions

§  I/O programming is fiddly.

Ø  Operating system abstractions to program..

                                                                                                                                   -nurul ain farhana-