This ingenious little device is the Dual EF Slot Scan Boot Adapter. Once installed in the IIe's EF ROM socket the Adapter allows you to instantly switch between booting 'normally' (Slot 7 to 1) and 'reverse' (Slot 1 to 7). Just a flip of a Jumper/Switch reverses the way your IIe scans it's Slots to look for a bootable device! No special configuration, software or tools needed.
The Dual EF Slot Scan Boot Adapter works with all non-Platinum Apple IIe's. It can be used with either a Jumper or the >Dual Adapter Switch<. The Adapter works by toggling the most significant address line of the ROM. The ROM in the Adapter is twice the normal size of the ROM that is normally in the IIe. One 'half' of the ROM contains the 'normal' IIe ROM code and the other 'half' contains the modified version of the ROM code. A Jumper or >Dual Adapter Switch< toggles the most significant address line and switches between each 'half' of the ROM. Think Binary - The normal ROM is 000 to 111 and our Adapter 'adds' another 0. The Adapter toggles the address from 0000 to 1000 - the first digit being the most significant . The IIe never knows the difference and the Adapter can be used even when the computer is on!
Most users have a >MicroDrive< or Hard Drive Controller in Slot 7. Now instead of hitting Control-Reset and typing 'PR#6' to boot to your Floppies just flip a Switch and boot. It's that easy!
The Adapter comes with a ROM and can be loaded with any custom versions of the IIe ROM that you have.
The ROM file is also available >HERE< for free if you wish to burn your own.
The Dual EF Slot Scan Boot Adapter is loosely based on the >Dual Character Generator< design and we wish to credit Bill Garber of >GarberStreet Enterprises< for inspiring its design. David Wilson is credited with creating the patch which allows the IIe to reverse scan boot, and without his help and ingenuity this item would not be possible.