z-machine on pdp8 (or paging Woodelf)

On 4/4/07, David Griffith <dgriffi at cs.csubak.edu> wrote: True. OTOH, it was a specialized VM implementation to solve only the problem of how to handle a 96K-128K file in a machine that might have 48K total, prior to OS overhead (thinking of the TRS-80 and Apple II). The initial Z-machine for the C-64 doesn't do any memory bank tricks, leaving it much less free space than 48K (later interpreters are much more elaborate). Years ago, I took the C-64 interpreter and patched it to run on the VIC-20. I never ran it on the real hardware, but when I stuffed RAM into every open orifice in the memory map (including lofting the interpreter into cartridge ROM space), it booted and ran numerous v3 games under VICE. If I had to estimate, I had between 28K and 32K of RAM for the game, plus 6K of "ROM" for the engine. 40K for the game, the rest of the machine could be taken up with OS overhead, I/O registers, etc. Wow... with the pure memory requirements/capacities of the v5 and larger game file formats, that's going to be difficult to juggle in RAM. At least OS/8 has a low memory footprint when applications are running. For those that are still reading this thread and haven't delved into the inner workings of a Z-machine... http://www.gnelson.demon.co.uk/zspec/appd.html -ethan