#MMU and mapped memory?
4 messages in this thread
All,
Ok, if you can create a memory mapper for things like ROM ala FASTROM, why
cant you create a similar item for moving chipram to warpmemory??? Maybe
I am out in the weeds on this idea. What do ya think, for those in the
know.
Alan Adamson
[72370,613] New WarpEngine owner…
Yep, you're out in the weeds.
Here's the problem, in a legume shell:
MMU's "map" addresses as they come out of the central processor (68000,
68040, etc) on the way to memory (both chip and fast) and I/o devices, in
the Amiga hardware design.
However, display memory is actually displayed by _another_ processor, one
of those you've heard about when the Amiga is described as having a form
of hardware multiprocessing, and that processor goes directly to chip
memory, and NOT tru the MMU. So, if you remap "chip" memory to somewhere
else, the CPU will dutifully read and write from and to that spot. The
display processor hardware, not having been channeled thru the MMU (which
is often, but not always, actually physically INSIDE the CPU), will still
fetch the "display information" from the same place.
What you end up with is a screenfull of "stuff" that the CPU hasn't done
anything to; so it's trash and you see nothing useful.
"You can't get there from here".
–Ben
…via AutoPilot
Ben,
Thanks, I should have know, but forgot about the special processors in the
Amy. Oh, well….hey while I have you. You guys (BBS) used to produce a
ham radio packet program right? How may of you guy are hams? The reason
I ask. I have ported over JNOS from the PC to Amiga….complete…so if
you do IP on packet, let me know…
Thanks,
Alan
We did the most powerful computer SSTV package available (so far) on any
computer, on the Amiga. We just released an AGA version of it, too. We
have a packet package, but it has sold so poorly as to be a severe
liability to us. Unfortunately… :^(
I don't do packet much myself, just log in to the emergency net here once
a week to check in and let 'em know I'm here if there's ever an emergency.
I like SSTV too much to spend any time on packet that I don't have to – If
I'm in front of the HAM rig I'm either listening to DX SW stations or
running SSTV RX or (very occasionally) TX.
–Ben
…via AutoPilot