Just to add my two cents, pence, etc..

I have successfully used SRAM instead of EPROM. Not as Von-Neumann Wired, but as a replacement chip for the EPROM.

The SRAM, needs a little pin config changes to look like the appropriate EPROM, and a battery backup controller, such as the Dallas DS1210, which prevents accidental writing to the SRAM while moving it from the programmer to the target system.

Programming in my case was done through a simple circuit attached to the parallel port of a PC, few latches etc. and a tiny little programmer proc written in C.

The result is a very fast prototyping system for writing & testing boot-strap programs, and getting a von-Neumann wired dev board up and working.

If this is of i