The Level 1 cache
is the fastest cache memory
on the CPU which is used for temporary storage of instructions and data organized
in blocks of 32 bytes. L1 cache is also known as Primary cache which is the
fastest form of storage, because it is built in to the chip with a zero
wait-state (delay) interface to the processor’s execution unit.
L1
cache is limited in size. It
is used to store data (critical files that need to be executed immediately) as
it is the first cache to be accessed and processed when the processor itself
performs a computer instruction.
The Intel’s
P55 MMX processor, launched in 1997, was in size of its Level 1 cache to 32KB.
The AMD K6 and Cyrix M2 chips launched later in that year, provided Level 1
caches of 64KB. 64KB remained the standard L1 cache size.
In recent
microprocessors, the L1 cache is divided equally into two cache : one cache to
keep program data and another cache to keep instructions for the
microprocessor. On other hand, some older microprocessors used undivided L1
cache which stored both program data and microprocessor instructions.
Level 1 cache is being
implemented by Static RAM (SRAM). SRAM uses two transistors per bit that hold
data without external assistance, till the power is supplied to the circuit.
The second transistor controls the output of the first transistor. The two transistor
forms a circuit known as a flip-flop because it has two stable states which it
can flip between. This is contrasted to dynamic RAM (DRAM), which must be
refreshed regularly per second in order to hold its data contents.
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