4 ms·

Quoting from the page itself: "It may be possible and worthwhile to also support some slightly later machines: The Acorn BBC Micro, Atari 400 and 800, and mayb

• vidarh 5y ago
  It'll take a more extensive modification than I thought, though, because it does a RAM mirroring thing that is necessary for performance but that kills compatibility with at least the C64. If you disable the RAM mirroring, all you need to make it compatible is to map the 6 IO pins to address $1. That "solves" the bank switching, but at the cost of killing performance totally as the chip will be starved for memory access most of the time. Judging from his pictures, he's using a version of the Spartan 6 (XC6SLX9) that has 72KB on-chip RAM, though, so unless he's using any of the RAM for anything else he could still mirror both the 64KB RAM + the KERNAL and BASIC ROMs. But he'd also need to keep track of various VICII registers to know which areas to designate as a "IO areas" to pass through writes for, given the VICII can address memory "everywhere" for sprites, fonts and bitmap data depending on what you write to different registers. Since that can at any time it'd involve a lot of "fun" logic to flush data from the on-chip cache to the C64 memory if a register changes.