Another approach

[dhouston]

I've finished designing Main boards that are Arduino form-factor and pin-compatible for DIP-24 and DIP-28 as well as one for DIP-40. The latter is pin-compatible except for added pins not present on the Arduino. My interest was to support ZBasic but the DIP-24 version will also support BasicX (BX-24) as well as BasicStamp2.

All use a simple serial interface and require an external SMPS (Switch Mode Power Supply) as I wanted to minimize cost. The DIP-28 & DIP-40 versions include a 64KB SPI EEPROM (ST M95512).

There are ZIP files containing JPGs of the boards on my web site.
DIP-28

The DIP-28 board can be 3V3 or 5V and has a socket for the crystal so it can use 7.3728, 14.7456 or 16MHz crystals. The first two are for 3V3 (ZX-328l) and 5V (ZX-328n). 16MHz is for Arduino - SparkFun sells an ATmega328 with the Arduino bootloader pre-installed.

I have not explored the Amicus18 pin-out but I understand it is not 100% pin-compatible with the Arduino so do not know whether these boards can be used with Amicus18 shields but they might serve as a pattern for anyone wanting a DIP-40 Amicus18. I will release the designs and Gerber files as Public Domain once I've been able to test them (3-4 weeks away).

There are ZIP files with JPGs on my web site - DIP-24 DIP-28 DIP-40