System utilizing multiple address decode resources and decoder receiving address determines address corresponding to resource based on select and ready signals by that particular resource

A method of carrying out a transaction at an address in a computer system having a fast resource, bridge logic, and an I/O resource, and a processing unit requesting said transaction, the method comprising the steps of:

• (a) if said address corresponds to said fast resource, then
• (i) said fast resource signaling with a first select signal within a predetermined time;
• (ii) said fast resource deasserting a ready signal;
• (b) if said fast resource does not signal within said predetermined time, then
• (i) said bridge logic deasserting said ready signal;
• (ii) said bridge logic forwarding said address to said I/O resource in an I/O transaction.

A method of carrying out a transaction at an address in a computer system having a first distributed decode resource, a central decode resource, a second distributed decode resource, a decoder, and a processing unit requesting said transaction, the method comprising the steps of:

• (a) if said address corresponds to said first distributed decode resource, then
• (i) said first distributed decode resource asserting a select signal to said decoder;
• (ii) said first distributed decode resource completing said transaction;
• (iii) said first distributed decode resource asserting a ready signal;
• (b) if said address corresponds to said central decode resource, then
• (i) said decoder asserting a second select signal to said central decode resource;
• (ii) said central decode resource completing said transaction;
• (iii) said central decode resource asserting said ready signal;
• (c) if said address does not correspond to said first distributed decode resource or said central decode resource, then
• (i) said decoder forwarding said address to said second distributed decode resource;
• (ii) said second distributed decode resource asserting a third select signal to said decoder;
• (iii) said second distributed decode resource completing said transaction;
• (iv) said decoder asserting said ready signal in response to said resource deasserting said third select signal.

A method of carrying out a transaction at an address in a computer system having a central decode resource, a distributed decode resource, a decoder circuit, a slow distributed decode resource, an I/O resource, and a processing unit requesting the transaction, the method comprising the steps of:

• (a) if said address corresponds to said distributed decode resource, then
• (i) said distributed decode resource asserting a first select signal to said decoder circuit;
• (ii) said decode circuit deasserting a ready signal;
• (iii) said distributed decode resource completing said transaction;
• (b) if said address corresponds to said central decode resource, then
• (i) said decoder circuit deasserting said ready signal;
• (ii) said decoder circuit asserting a second select signal to said central decode resource;
• (iii) said central decode resource completing said transaction;
• (c) if said address does not correspond to the distributed decode resource or the central decode resource, then
• (i) said decoder circuit deasserting said ready signal;
• (ii) said decoder circuit forwarding an I/O cycle to said I/O resource;
• (d) if said address corresponds to said slow distributed decode resource, then
• (i) said slow distributed decode resource asserting a third select signal to said decoder circuit;
• (ii) said decoder circuit aborting said I/O cycle;
• (iii) said slow distributed decode resource completing said transaction.

A computer system comprising:

• a bus;
• a processing unit coupled to request a transaction on said bus;
• a distributed decode resource coupled to receive an address of said transaction from said bus and coupled to drive a first select signal and to deassert a ready signal if said address corresponds to said distributed decode resource;
• a central decode resource coupled to receive said address from said bus and coupled to receive a second select signal;
• a decoder coupled said bus to receive said address, to receive said first select signal, and coupled to drive said second select signal and deassert said ready signal if either said address corresponds to said central decode resource, or said address does not correspond to either of said central decode resource and said distributed decode resource.