READ ENABLE — When RAMCard RAM is read-enabled, status bit 1 will be high. When Apple on-board ROM is enabled, status bit I will be low. This state applies immediately following power on. When RAMCard RAM is read-enabled, an INH signal generated by the ICs in sockets U12 and U13 disable the ROMs on the Apple motherboard.

WRITE ENABLE — When RAMCard RAM is write-enabled, status bit 2 will be high. The state applies immediately following power on. When RAMCard RAM is write-protected, status bit 2 will be low. NOTE: Write-enable remains on until a write-protect control address is accessed. Therefore, accesses to a write- enable control address subsequent to a write-enable will write to RAMCard RAM unless a write-protect access intervenes. This state applies immediately following power on.

NEXT — To protect RAMCard RAM from accidental write- enable, two consecutive accesses to a write-enable control address are required. When the first access has been done, the NEXT flag is set, and status bit 3 is high. When the second access has been done and RAMCard RAM is write-enabled, the NEXT flag is turned off, and status bit 3 is low.

LED Indicators

Three LED indicators are attached to RAMCard along the top edge. Next to each LED is a label which describes the functions that the LEDs signal. The three labels are BANK 1, RAM READ ENA, and RAM WRITE ENA. The LEDs indicate whether the bank or function is on (selected) or off (deselected), but not whether an access is occurring or not. The LEDs indicate the following:

LED

ON

OFF

BANK I

4K BANK 1

4K BANK 2

 

selected

selected

RAM READ ENA

RAMCard RAM

Apple II ROM

 

read selected

selected

RAM WRITE ENA

RAMCard RAM

RAMCard RAM

 

write-enabled

write-protected

The LEDs may be on or off in any combination because the banks and functions may be selected in any combination. At power-on/RESET, RAM WRITE ENA LED is on; the other two LEDs are off.

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