I have taken the design of this computer one step further and added an SPI EEPROM IC on-board allowing full size (over 7KB) BASIC programs to be saved. The following image shows the prototype PCB of this new design:
This PCB was created using the PCB Train 1 day turnaround prototype manufacture service to ensure the new design works (not shown on the above PCB is a power LED which was added after this PCB was ordered). As can be seen from the following image, the new design works correctly so I will be ordering a batch of PCBs and will be putting them on eBay.
A BASIC program was actually already stored in the EEPROM IC (as I took the IC from the red EEPROM cards shown in the details section of this page) and was loaded upon booting the computer showing EEPROM access works correctly.
I will be ordering the batch of PCBs now (they will be white in colour with ENIG finish) and will post when they have arrived. Also, the name of the computer has been changed from "Single Chip Computer" to "AVR BASIC Computer V0.1" due to addition of another IC.