You'll find two no-frills boards that I designed with a simple problem to solve: allow me to install multiple Kickstarts in my Amiga 500 rev.5 units without having to shell out money for an expensive 27C400 that I then need to rewire to make compatible.

The board includes sockets for pullup resistors that are oftentimes required (if your Amiga doesn't already have them) when fitting an new EPROM.

The board accepts two 27C020/040/080 EPROMs programmed with concatenated Kickstart images.

EPROMs Configuration

The Amiga 500 uses a 16-bit bus to access the Kickstart, as such, the original ROM and its replacements must be 16-bit memories: expensive and annoying to program.

This board merges the data path of two 8-bit EPROMs (cheaper, easier to program) to rebuild the 16-bit data path.

One must take care to divide the original Kickstart dumps in two halves by separating the most significant byte of each Word into a file, and the least significant into another.

A500 rev.5 configuration

The Amiga 500 rev.5 uses a non-standard pinout in its Kickstart socket: A17 line is connected to PIN 31, while it is normally on PIN 1 of the ROM chip.

You can wire the adapter to use this pinout by bridging pins 2-3 of the J4 header. If pins 1-2 are bridged, the A17 line goes to PIN 1.

A18 and A19 are pulled-up through 4.7k resistors.

Every slot can host a 512kb Kickstart. If you wish to put a 256kb Kickstart in the slot, concatenate it with a copy of itself (stay on the safe side!).