For now, Heritage / 1 does not provide this hardware support for Virtual Memory. I do not think it will be difficult to implement in a second step (after the machine is "In use") and make it so that it fits into the architecture, without violating.
Why Virtual Memory? "Because, contrary to what I imagined at first, Virtual Memory is not a" luxury ", on the contrary, its lack is a pretty serious limitation when you think of an operating system itself. It will take some time before me entangled in these matters but the time will come, and I will be trying to carry a "UNIX-like" as Minix OS or NetBSD, I do not think homework is viable (or even possible) on a machine without support Virtual Memory.
When I looked at these issues for the first time (just six months ago) I felt that the role of Virtual Memory is more in the protection of processes and the establishment of a linear model of memory for applications with which the OS is committed to more memory (virtual) of the physically available (thanks to " swapping "). Maybe that's why it did not seem particularly attractive in a design that boasts simple. Now, however, I am seeing the benefits of Virtual Memory in another sense, and it has to do with the burden of program memory.
The OS (or rather a component of his called "loader") is responsible for loading each program storage memory and when it does, you need to "relocate", that is, change (the fly) the flow control statements (such as JP and CALL) in conjunction with the base address assigned to the program.
Actually I planned to avoid the need for "relocation" using relative addressing instructions (which I still think a good idea), but even using direct addressing instructions, a loader can recalculate all the jumps without too much difficulty (as I think) but it consumed some time, of course.
elegant solution, however, would carry the burden of the program in the domain of linear memory, provided by Virtual Memory, for which the duty to provide the proper hardware support. In If so, each program would have its own virtual memory address which covers the entire addressable space (64K), the hardware is responsible for mapping the addresses of each application to real space physical memory installed, the OS would be responsible for maintain the mapping and in addition, implement process protection rules. And the "loader" is limited to map the new program within the Virtual Memory system.
But as I said earlier, that same support will be implemented in a second step, once Heritage / 1 is "in use".
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