Found these inside a non-working 71B

[Paul Berger (Canada)]

(03-12-2018 04:04 PM)MikeSD Wrote:  Something is still wrong then. I removed the wire add mem still says 15,391. Consistent but wrong. I'll buzz everything out again when I get home. I'm going to spend a little more time on this, then go remove the FORTH and see if the 71B is working without these.

Even sys RAM can be made independent with FREE and CLAIM. How is this RAM referenced?

When you you issue a free port command three things happen. First the whole module at the port address is zeroed, then an identifier is written into the first few nibbles of the modules memory, and it is reassigned an address closer to the top of memory with ROM modules and other port RAM. Freeport will only work if there is sufficient free memory to allow it and files in memory may be relocated. When you issue a claim port the the free port identifier is cleared, in fact I believe the whole module is cleared and the module is readdressed nearer the bottom of memory. That is just the basics of what happens there are a whole lot of memory management things that go on when either free port or claim port are issued.

Paul.