Computer Science

Inside the machine

manufactured. These internal connections are either to earth (zero voltage)

or to the supply voltage connection (the one voltage), and are made using

conducting silicon.

Because a masked ROM is manufactured using very expensive tooling and

the contents of the ROM are unalterable, this method is used only when the

contents are well tested and required in large numbers. When the ROM is

used only to boot in an operating system, this is by far the cheapest method,

because the requirements are simple and unchanging. The desktop com-

puters which used their own operating systems often placed them in ROM,

but this had the disadvantag ...