When I started to put together the compact flash drive, I found that the Interak CPU card would have to be completely changed. Mainly because it has the Boot ROM included.

So I abandoned the CPU card and the RAM card.  I made up a separate ROM/RAM card – this card has the Boot ROM and SRAM. Now when the Interak is booted the Boot ROM
 will copy itself to address 8000H then jump to this address and switch off the ROM.

There is a flip-flop which then stays off until a reset occurs.

The code at 8000H then loads the CP/M system which is on the first track of the compact flash - or loads the floppy disk system if 'F' is pressed.

There are not many I.C's on the ROM/RAM card (9 but 4 of them are buffers) so it could possibly be combined with the CPU/Compact Flash card. But I think it is best to keep it separate
 in case of any changes in the future, and to keep the Interak as flexible as possible.

As this circuit only occupies about half the space of a standard Interak card I used a VERO D.I.P.Board No.10-0144. At 165mm it is a bit shorter than the Interak card, it also has a 
gold-plated 43-way edge connector.... may no longer be available.

The Boot ROM is an AT28C256, same as the character generator. The Boot ROM code is 4.5K so any EPROM or EEPROM will do.