Basic Types of Address Decoding
- Exhaustive — 1:1 mapping of unique addresses to one hardware register (physical memory location)
- Partial — n:1 mapping of n unique addresses to one hardware register. Partial decoding allows a memory location to have more than one address, allowing the programmer to reference a memory location using n different addresses. It may also be done just to simplify the decoding hardware, when not all of the CPU's address space is needed. Synonyms: foldback, multiply mapped, partially mapped.
- Linear — Address lines are used directly without any decoding logic. This is done with devices such as RAMs and ROMs that have a sequence of address inputs, and with peripheral chips that have a similar sequence of inputs for addressing a bank of registers. Linear addressing is rarely used alone (only when there are few devices on the bus, as using purely linear addressing for more than one device usually wastes a lot of address space) but instead is combined with one of the other methods to select a device or group of devices within which the linear addressing selects a single register or memory location.
Read more about this topic: Memory-mapped I/O
Famous quotes containing the words basic, types and/or address:
“The basic tool for the manipulation of reality is the manipulation of words. If you can control the meaning of words, you can control the people who must use the words.”
—Philip K. Dick (1928–1982)
“... there are two types of happiness and I have chosen that of the murderers. For I am happy. There was a time when I thought I had reached the limit of distress. Beyond that limit, there is a sterile and magnificent happiness.”
—Albert Camus (1913–1960)
“It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our necessities but of their advantages.”
—Adam Smith (1723–1790)