With the last Post, I decided that I would modify the system a little, with a modification to add nor three bit four Secondary Stack Pointers, simply by removing the PC Offset Register from the Special Registers. This does not however mean that I remove the relative jumps, those are dealt with separately.
This post is the result of me listening to this week's episode of the Advent of a computing podcast, the Jupiter Ace. The Ace was a small micro from 1982/83, designed by two guys that worked on the software and hardware of the Sinclair ZX-81. The hardware was pretty much the same as the ZX-81, but it had one big difference.
Instead of BASIC, the Ace ran Forth, a stack based language that is small, easy and fast.
This section contains a basic design of the DWMC-16 Operations and their OpCode design, meaning how operations are going to be represented in memory.
While I am thinking about the Memory Addressing Modes, I noticed that that if I am to use Relative Addressing, that is an address relative to the Program Counter, I may need to add a PC Offset Register in the Special Use Register Block. So I had to modify the basic design a little to add this new register.
This is the general design for the IO systems used by the DWMC-16.
As the IO System is mapped into a sector in memory, it does share the same subdivision into 4 kiWord memory blocks, with each block of memory used to address one IO module.