🚀 go-pugleaf

The suggestion of O/S on cartridge could be useful, but especially so if the
cartridge could be removed immediately after boot-up so that other cartridges
could be used.  One way to do this would be to provide RAM "hidden under the
O/S ROM" a la the XL/XE machines, and to make the O/S update cartridge switch
in the RAM and copy the updated O/S there, then return control to the copy.
Possibly the code that did the copying could be in a separate chip or
otherwise designed so that the actual updated O/S ROM could be in a socket in
the cartridge and could be popped out and installed inside the ST at the
customer's convenience.  Then the cartridge could be mailed back to ensure
that the next update would be received.  Or kept for building homebrew
cartridges, at the customer's option.

Possibly this option could be provided in the ST machines by means of empty
memory sockets which the user could fill with RAM if he/she wanted the
Cartridge O/S option; otherwise they could be left empty.  However, 256K DRAMs
are getting pretty cheap these days, so probably the board space would be more
precious than the cost of the RAMs.  If 1M DRAMs or larger were used, logic
should be provided to "split" its address space so that the portion not needed
for the O/S would appear contiguous to the main memory space.

-John Sangster, jhs@mitre-bedford.arpa
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