4

The Commodore 64 was very flexible in terms of how RAM could be controlled. ROMs and I/O devices could easily be swapped out by setting bits in the first two addresses of memory. The VIC-20's ROMs and I/O devices seem to be hardwired to certain addresses, and can't be disabled.

Was there any sort of bank-switching(?) RAM expansion that enabled the VIC-20 to break the 40 KiB Barrier?

(40 KiB is whats let of the address space after ROM and I/O)

I'm not looking for any modern development, but contemporary expansions (i-e- of the 1980s. Of course everything with more than 64 KiB is as wellcome.

  • 1
    What I mean is a device that was actually used by the community back in the 1980s, as opposed to some new expansion for retrocomputing enthusiasts. – Serentty Jul 27 at 18:29
  • Ok, I just reformatted your question a bit to make the point clear. If you don't like it, ust revert. – Raffzahn Jul 27 at 18:49
4

There were several cards, in the mid 1980s, based on use of 64 KiB. Except that it was usually not to use full 64 Kib, but to get RAM at the right location some (game) program wanted it.

For example this page shows three different boards of that time frame.

The main issue with RAM in the VIC20 is less the amount of RAM, than that its use swaps around, depending how much memory is installed. So more care was taken to enable different configurations with simple switching. There is an overview on the VIC20 Wiki page.


And yes, there is of course new stuff like the fine crafted Final Expansion offering half a megabyte :))

  • Okay, so there were contemporary RAM expansions larger than 35 KiB that involved swapping that RAM in and out of the gaps in the address space, essentially? – Serentty Jul 27 at 18:53
  • 1
    There were several cards offering more than the 32 KiB the VIC normally can do. Most common use was to page in 8 KiB at A000 to enable loading ROM games from Floppy. At least one was able to allow more than 40 KiB (48?) for BASIC by modyfying BASIC to work much like the C16 machines which could use more than 50 KiB for basic by switching the ROMS in and out. I need to search, it's been a long time. – Raffzahn Jul 27 at 19:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.