Microprocessor Specifications

Microprocessors are classified and compared on the basis of a handful of key features: chip type, word size, memory size, clock speed and cores. These are exactly the columns of the generations table (Table 1.2); here each specification is explained.

(A) Word size

Word size is the maximum number of bits a microprocessor can process at a time.

• In early processors, a word was 8 bits — the maximum possible at that time.
• At present, the minimum word size is 16 bits and the maximum is 64 bits.

A larger word size means the processor can handle bigger chunks of data in a single operation.

(B) Memory size

The amount of RAM a processor can use depends on its word size — the word size limits how much memory the processor can address.

• Initially, with 4/8-bit word sizes, RAM was very small (4 MB).
• With today's 64-bit word size, it has become feasible to use RAM of up to 16 Exabytes (EB).

This is why the "maximum memory size" column in Table 1.2 grows in step with the word-size column.

(C) Clock speed

Computers have an internal clock that generates pulses (signals) at regular intervals of time. Clock speed is the number of pulses generated per second by this clock.

• The clock speed indicates how fast the computer can execute instructions — each pulse paces the processor's work.
• Earlier clock speeds were measured in Hertz (Hz) and Kilohertz (kHz); with advances in technology and chip density, they are now measured in Gigahertz (GHz) — billions of pulses per second.

(D) Cores

A core is a basic computation unit of the CPU.

• Earlier processors had only one computation unit, so they could perform only one task at a time. …