Memory Banks64KB of memory should be enough for experimenting with low-level software, even with peripherals mapped in that space. However, we can extend the range by using a Memory Banks scheme.
We can store the Bank Number in a 8-bits hidden register. An instruction maybe termed SETBNK (number) would be employed to switch banks. This allows for 256 banks, that is 16MB of memory.
This could be also exploited as a rudimentary support for protected multi-tasking. If the OS manages to allocate different processes in different banks (64K per process) and development tools (Assemblers, Compilers and Linkers) are designed not to allow SETBNK instruction in "Application Development Mode", then it would be nearly impossible for application code to trespass process boundaries.
As per address lines, the internal address bus (A-BUS) would still 16 bits whereas the external address bus (that in U-BUS) would have 24 lines, the 8 most-significant ones being fed from the BANK register.
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Project start date: May 13 of 2009
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