RAM AND ROM (MIS)

SARJANA MUDA PENGURUSAN MARITIM
MMM3501 SISTEM MAKLUMAT MARITIM (K1)

NAMA PELAJAR : NUR HANISAH BINTI HUSSIN
NO. MATRIK : S54965

RAM

• Definition of RAM
• RAM is a part of computer’s Main Memory which is directly accessible

by CPU. RAM alternatively referred to as main memory, primary memory, or
system memory. RAM also is a hardware device that allows information to be
stored and retrieved on a computer. However, RAM is a volatile memory and
requires power to keep the data accessible . If the computer is turned off, all
data contained in RAM is lost.

INTEGRATED RAM CHIPS ARE AVAILABLE IN TWO
FORM:

• SRAM (Static RAM) • DRAM (Dynamic RAM)

The SRAM memories consist of circuits DRAM stores the binary information in the
capable of retaining their stored form of electric charges that applied to
information as long as the power is capacitors tend to lose over the period of
applied. That means this type of memory time and thus the capacitors must be
requires constant power. SRAM memories periodically recharged to retain their
are use to build Cache Memory. usage. The main memory is generally
made up of DRAM chips.

• SRAM Memory Cell • DRAM Memory Cell

Static memories (SRAM) are memories Though SRAM is very fast, but it is
that consist of circuits capable of expensive because of its every cell
retaining their state as long as power requires several transistors. Relatively
is on. Thus this type of memories is less expensive RAM is DRAM, due to
called volatile memories. the use of one transistor and one
capacitor in each cell.

TYPES OF DRAM

1) Asynchronous DRAM (ADRAM) - The timing of the memory device is controlled asynchronous.

A specialized memory controller circuit generates the necessary control signals to control the
timing.

2) Synchronous DRAM (SDRAM) – these RAM chips’ access speed is directly synchronized with

the CPU’s clock.

3) double-Data –Rate SDRAM (DDR SDRAM) – this faster version of SDRAM performs its

operations on both edges of the clock signal , where as a standard SDRAM perform its
operations on the rising edge of the clock signal.

4) Rambus DRAM (RDRAM) – The RDRAM provides a very high data transfer rate over a

narrow CPU-memory bus.

5) Cache DRAM (CDRAM) – this memory is a special type DRAM memory with an on-chip

cache memory (SRAM) that acts as a high – speed buffer for the main DRAM.

DIFFERRENCE BETWEEN SRAM AND DRAM

SRAM DRAM
1) DRAM has higher access time, so it is slower
1) SRAM is lower access time, so it is faster
than SRAM.
compared to DRAM.
2) DRAM costs less compared to SRAM.
2) SRAM is costlier than DRAM.
3) DRAM offers reduced power consumption,
3) SRAM requires constants power supply, which
due to the fact that the information is stored
means this type of memory consumes more in the capacitor.
power.
4) Due to the small internal circuitry in the one-
4) Due to complex internal circuitry, less storage
bit memory cell of DRAM, the large storage
capacity is available compared to the same capacity is available.
physical size of DRAM memory chip.
5) DRAM has high packaging density.
5) SRAM has low packaging density

ROM

• Definition of ROM

ROM is a storage medium that is used with computers and other
electronic devices. As the name indicates, data stored in ROM may only be
read. It is either modified with extreme difficulty or not at all. ROM is mostly
used for firmware updates. A simple example of ROM is the cartridge used with
video game consoles, which allow one system to run multiple games.

ADVANTAGES OF ROM

1) Non-volatile in nature
2) Cannot be accidentally changed
3) Cheaper than RAMs
4) Easy to test
5) More reliable than RAMs
6) Static and do not require refreshing
7) Contents are always known and can be verified

DISADVANTAGES OF ROM

1) ROM is slower type of memory.
2) On some special types of ROM, user can only alter its contents ones.
3) Its information can only be retrieved (read) but user cannot delete, alter or

overwrite its contents except for special type of ROM.

4) Unlike RAM, incorrectly erasing ROM contents will brick the memory (makes

it in unusable).

TYPES OF ROM

1) MROM (Masked ROM) – the very first ROMs were hard-wired devices that

contained a pre-programmed set of data or instructions.

2) PROM (Programmable Read Only Memory) – PROM is read-only memory that can

be modified only once by a user.

3) EPROM (Erasable and Programmable Read Only Memory) – EPROM can be

erased by exposing it to ultra-violet light for a duration of up to 40 minutes.

4) EEPROM (Electrically Erasable and Programmable Read Only Memory) – it can be

erased and reprogrammed about ten thousand times.

IMPORTANT OF ROM

• ROM provides the necessary instructions for communications between various

hardware components. As mentioned before, it is essential for the storage and
operation of the BIOS, but it can also be use for basic data management, to
hold software for basic processes of utilities and to read and wite to
peripheral devices.