ELITE SERIES USER MANUAL

THEORY OF OPERATION

The second type of command is the bank select command, characterized by a write by the Apple CPU to the address space occupied by the controller ‘S EPROM. The bank select commands are only enabled when the controller’s EPROM is switched into the peripheral expansion space. An LED indicates when drives 3 and 4 (Bank 1) are selected.

 

Address to Write

Drives Selected

(data ignored)

1 and 2

$C800

3 and 4

$C801

(Writes to other addresses between $C800 and $CFF7 are also possible but may not be supported in later card revisions).

Fig. 7-6: Controller Bank Select Addresses

The third type of command is the EPROM switches. These control whether the EPROM is enabled for the $C800-CFFF peripheral expansion space. An LED indicates when the EPROM is switched on.

EPROM Switch

Address to Access

Turn

on at $C800-CFFF

$Cn00-cnFF

(n = slot #)

Turn

off EPROM

$CFF8-CFFF

 

Fig. 7-7: Controller EPROM Map-In/out Addresses

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