Ed Eastman wrote:
Nothing flips the annunciators unless they are part of its functioning. The Apple ROM reset code presets all annunciators (two on and two off) and DHR will tickle AN3.So make slot select part of the hardware on the slot selector and use a preboot program to select the card desired. ;)No, you would not need to use the given slot's rom/I/O space, use something that is not used somewhere in the apple and make a logic to sense it. (softwswitch) Eg: How about a quick circuit to detect a write to address FFFF and latch the state of bit 7 of the data line using a D flip-flop for example? Use a switch to send the reset line to either select set or reset on the FF for default operation of which slot you want active on boot. Use more bits and you could get really creative with Aux SLOTS!!! (What do you mean your Apple has 14 slots, all software selectable? :)
ISTR that the ROM chip selects are not qualified by R/W, so a write to ROM space would create a bus fight. Also, a 16-bit AND gate is a little wide. ;-) -michael 8-voice music synthesizer using NadaNet networking! Home page: http://members.aol.com/MJMahon/