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Addressing information is divided into three sections in this chapter. The first section shows memory maps. The maps show the memory addresses for the functions called through control addresses. The second section describes these control addresses, which provide memory mode selection, RAM write-enable/-protect, and bank switching. The third section describes additional technical details about status bits, about the LED indicators on RAMCard, and about RAMCard hardware details.

Memory Maps

The following diagrams illustrate the range of addresses used for the memory functions of RAMCard and the Apple on-board ROM.

FFFF

 

 

RAMCard

 

Apple

RAM

 

on-board

 

 

ROM

E000

 

 

 

 

DFFF

 

 

BANK 2

BANK 1

D000

Control Addresses

The control addresses are special memory addresses that, when ac- cessed, control simultaneously three unrelated functions:

1. Select write-protect or write-enable RAMCard’s RAM

2. Select RAMCard RAM read or Apple II on-board ROM

3. Select which 4K bank will be mapped into the $D000-$DFFF addressing space.

Because the address space $C000-$CFFF is used by the Apple.

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