[Coco] 512K AND Beyond??? How FAR Beyond???

[Richard Cavell]

   Hi everyone. I just want to offer my two cents.

   Would it be possible to set aside a few bytes of the address space to
   function as bank-switching registers, and then construct a custom
   bank-switching mechanism to add more memory via a cartridge?  Using
   this mechanism you could add any amount - even gigabytes.

   But the 6809's ability to retrieve and process that memory is limited.
   Once your program genuinely needs more than a few megabytes of RAM to
   be simultaneously accessible, the 6809 is no longer the correct CPU to
   be using.

   Richard

   Sent: Wednesday, December 27, 2017 at 4:09 PM
   From: "Bill Pierce via Coco" <coco at maltedmedia.com>
   To: coco at maltedmedia.com
   Cc: "Bill Pierce" <ooogalapasooo at aol.com>
   Subject: Re: [Coco] 512K AND Beyond??? How FAR Beyond???
   Robert, Jim and anyone else, OS9 did NOT use memory above 2 meg. The
   only software I know of using this is the ramdisk in the NitrOS9
   repository specifically written for Paul Barton's 8 meg board and it
   accesses the memory directly and not through OS9's memory manager. Of
   course, there's Robert's test programs as well.
   The DAT tables required for anything above 2 meg are too large for
   system memory and something would have to be modified/changed before
   NitrOS9 can "legally" use memory above 2 meg.
   That being said, the memory above 2 meg CAN be used with special
   programming... as data space, graphics memory storage, etc, but the
   program itself would have to keep tabs on what memory is being used and
   what memory is free (above 2 meg). A good example of this is Dave
   Philipsen's BMP display demo for the Coco3FPGA which loads 20+ 640x450,
   256 color BMP files into memory the runs a slideshow. The Coco3FPGA
   DOES have some memory and graphics functions that a Coco3 does not, but
   it would still work on a Coco3with standard Coco3 res screens (with a
   little modification to the software)... and store about 40-50 (maybe
   more, too lazy to do the math) 640x192 graphics screen!!
   [1]https://youtu.be/WlcjJLiOQbQ
   and while playing a wav file!!
   [2]https://youtu.be/G8a9-6R7wh0
   And yes, this was done in NitrOS9 on the Coco3FPGA @25mhz!!
   Also, to clear something up... I keep seeing that the 1-2 meg is "just"
   used for ramdisks... Yes and no. This is only true IF that's what you
   assign it to.
   The 1-2 meg upgrades are used in NitrOS9 as REGULAR mappable memory. In
   other words, if you're running programs, you have more memory for more
   programs. More graphics pages and windows can be assigned. More/larger
   get/put buffers can be used and much more. This is all transparent to
   the user, no special commands needed... NitrOS9 just has more memory.
   The 64k workspace limit still applies, but you can have even have more
   64k workspaces. It "Just Works".
   A good example of this would be Ultimuse3. It is originally configured
   to a 256k score buffer. With the change of a single variable, it can
   use up to 1.5 meg (system and program use the rest) for the score
   buffer. I may make this change on the next release :-)
   Another example is my MShell project. The MShell File Manager reads 2
   complete directories into memory. On large HD directories or PC
   directories (yes, MShell will read/copy directly from your PC HD using
   DW4), you could read massive directory into memory. MShell dynamically
   allocates the memory for the huge buffers using get/put buffers and
   will utilize the 1-2 meg upgrades (all done "legally"). MShell also
   forks various modules as it runs. With more memory, MShell easily
   handles the forking of subs along with massive data buffers for program
   use (not to mention other programs running in other windows) and it's
   all transparent to the user. MShell doesn't do anything special to use
   this memory, it works with 512k or above. All the heavy lifting in the
   memory management is done transparently by NitrOS9.
   To say "it's not used" or "who would need it?" is just saying "You
   never had it!". I've been running my real Coco3 with 1 meg and VCC with
   2 meg for years and when I go back to 512k, I get frustrated when I run
   out of memory for extra processes, windows, or graphics.
   The Coco3 memory upgrades above 512k fall in that category of "You
   don't know you need it until you've had it and then have to do without
   it"
   I'm lost on a 512k machine these days.
   Bill Pierce
   "Charlie stole the handle, and the train it won't stop going, no way to
   slow down!" - Ian Anderson - Jethro Tull
   My Music from the Tandy/Radio Shack Color Computer 2 & 3
   [3]https://sites.google.com/site/dabarnstudio/
   Co-Contributor, Co-Editor for CocoPedia
   [4]http://www.cocopedia.com/wiki/index.php/Main_Page
   E-Mail: ooogalapasooo at aol.com
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References

   1. https://youtu.be/WlcjJLiOQbQ
   2. https://youtu.be/G8a9-6R7wh0
   3. https://sites.google.com/site/dabarnstudio/
   4. http://www.cocopedia.com/wiki/index.php/Main_Page
   5. https://pairlist5.pair.net/mailman/listinfo/coco