16 Glossary
VRAM
Video RAM. VRAM is special-purpose memory used by video adapters. Unlike
conventional RAM, VRAM can be accessed by two different devices
simultaneously. This enables a video adapter to access the VRAM for screen
updates at the same time that the CPU provides new data. VRAM yields better
graphics per f or mance but is mor e expensive t han normal RAM. A special typ e o f
VRAM, called Windows RAM (WRAM), yields even better performance than
conventional VRAM. See SGRAM and WRAM.
Wwarm boot
Process of resetting the computer without turning off the power through keyboard
input (pressing Ctrl, Alt, and Del keys simultaneously) or the reset button. The
system returns to an initial or arbitrar ily selected condition.
WRAM
Windows RAM. A type of RAM that supports two ports. This enables a video
adapter to fetch the contents of memory for display at the same time that new bytes
are being pump e d i nto memory. T his results in much f a ster display t han is possibl e
with conventional single-port RAM. WRAM is similar to VRAM, but achieves
even faster performance at less cost because it supports addressing of large blocks
(windows) of video memory. See VRAM and SGRAM.
write
To record or store i nf ormation to a s torage devic e.
write-back
Also called copy back. A cache strategy where write operations to data stored in the
internal micropr ocessor L1 cac h e aren’t copied to s ys t em memory until a bsolutely
necessary. I n co ntrast, a writ e-through cac h e performs all wr ite operations in
parallel; dat a is written to syst em memory and t he L1 cache simu lt aneously. Wr ite-
back caching yields somewhat better performa nc e tha n write-through caching
because i t reduces the numb er of writ e operat ions to ma in memor y . See cac h e and
write-thr ough.
write-through
Also write-thru. Write-through characterizes a cache strategy where data is always
written into s ys tem memory whe n da ta is written b y the CPU. See cach e and write
back.