Editing Autoconfig (section)

== Protocol ==
Expansion devices respond to certain fixed memory addresses starting at  hexadecimal {{nowrap|0xE8 0000}} (or {{nowrap|0xFF00 0000 }} for [[Zorro III]]) if the /CFGIN signal is asserted and the device is not already configured. The [[Central processing unit|CPU]] reads [[nibble]]s of configuration information (usually supplied by a [[Programmable array logic|PAL]]) such as manufacturer ID, product ID, and the amount of address space the device requires. The CPU then writes a base memory address to the device (or tells it to "shut up" if for some reason it can't be configured), and the device asserts /CFGOUT.

The /CFGIN of the first device is tied to ground. The second device's /CFGIN is controlled by the first device's /CFGOUT, and so on.

In a [[backplane]] design such as the [[Amiga 2000]], connecting the /CFGOUT of one slot directly to the /CFGIN of the next would create the problem that an unoccupied slot would break the configuration chain. To solve this, the backplane [[Logical disjunction|OR]]s the /CFGIN and /CFGOUT signals to form the /CFGIN for the next slot (/CFGOUT is pulled low if undriven), which allows empty slots to be bypassed. This requires one [[7400 series|74LS32]] (quad OR gate) on the Amiga 2000, which is the only [[motherboard]] hardware required by Autoconfig.<ref>{{cite web |url=http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node02C7.html |title=K / AUTOCONFIG(TM) / The Autoconfig Mechanism |last=Pic |first=The |orig-date=April 29, 2021 |access-date=2021-04-29 }}</ref>