Re: Mega 4 two chip TOS with no 74LS11
Posted: Thu Nov 25, 2021 9:17 am
exxos' hunch is likely correct - an "advanced" TOS 2.06 decoder. Pasting in my FB comment:
/Troed
edit: The other three CPU connections are AS, RW and DTACKDef. a TOS switch of sorts. "New TOS" or "Old 2 chip" / "Old 6 chip". It's picking up ROM2 from the G19 connection to GLUE. However, there's more involved that I'm not sure I understand (like G24 - 'DMA'). It's picking up the whole top address byte from the 68000 so I'm assuming it's able to do some software switching too. Or just an interesting way of getting TOS 2.06 running through address space changing.
/Troed