On the Master I could fairly easily extend the TPA up into the sideways RAM area, adding another 16kB, for a total of probably about 45kB. The difficulty is that filesystems in Acorn's MOS can't access sideways RAM directly, as that's where the filesystem module itself lives, so all I/O would have to be done by copying the data to low memory, calling MOS, then switching the sideways RAM back in again afterwards. There may also be subtleties in catching interrupts and things which might try to change sideways RAM pages. But it should totally work.
For the _really_ advanced version, it could run bare metal and reuse the OS workspace at 0xc000 all the way up to 0xe000. But that would lost all MOS services, so would have to reimplement things like screen redrawing and floppy disk handling.
On the Master I could fairly easily extend the TPA up into the sideways RAM area, adding another 16kB, for a total of probably about 45kB. The difficulty is that filesystems in Acorn's MOS can't access sideways RAM directly, as that's where the filesystem module itself lives, so all I/O would have to be done by copying the data to low memory, calling MOS, then switching the sideways RAM back in again afterwards. There may also be subtleties in catching interrupts and things which might try to change sideways RAM pages. But it should totally work.
For the _really_ advanced version, it could run bare metal and reuse the OS workspace at 0xc000 all the way up to 0xe000. But that would lost all MOS services, so would have to reimplement things like screen redrawing and floppy disk handling.