CHAPTER 10

Read-only memory

Read-only memory

contains system software and permanent system data

RAM

contains temporary data and application software

400H

Represents a 1K-byte section of the memory system

Byte-wide memory

An 8-bit-wide memory device is often called

Output enable (OE) or gate (G

The control input most often found on a ROM is the __which allows data to flow out of the output data pins of the ROM

Nonvolatile memory

This type of memory is often called__ because its contents do not change even power is disconnected

EPROM (erasable programmable read-only memory)

a type of ROM, is more commonly used when software must be changed often or when too few are in demand to make the ROM economical.

EPROM programmer

An EPROM is programmed in the field on a device called

PROM (programmable read-only memory)

is also programmed in the field by burning open tiny NI-chrome or silicon oxide fuses; but once it is programmed, it cannot be erased

Flash memory

Newer type of read-mostly memory (RMM

Flash memory device

is used to store setup information for systems such as the video card in the computer

Static memory

Because no special action (except power) is required to retain stored data, these devices are called

Volatile memory

Because they will not retain data without power

SRAM

Which stores temporary data, is used when the size of the read/write memory is relatively small

SIMMS

are cumbersome to use because they must be used in pairs to obtain a 64-bit-wide data connection

RIMM

contains 168 pins, but each pin is a two-level pin, bringing the total number of connections to 336

Cold-start location

We often call location FFFFOH the

SECDED (single error correction/double error correction)

an 8-bit error correction and detection circuit that corrects any single-bit memory read error and flags any 2-bit error called

low bank

holds all the even numbered memory location

high bank

holds all the odd-numbered memory locations

Synchronous dynamic RAM (SDRAM

is used with most newer systems in one form or another because of its speed

Double-data rate (DDR

memory is the latest improvement in a long string of modifications to DRAM.