It would complicate connections and clocking but a SO input could be partially emulated (in a synchronous fashion) by boosting the cpu speed, executing a SEP #xx to set overflow, and BRA'ing back to where the cpu was before returning to host bus speed. That has the massive caveat of the cpu having to be taken completely off the bus during the emulation and would probably still require a clock cycle. Perhaps not if done quickly enough. Just a semi-educated brainstorm on emulating SO if it's needed On Mon, Jul 16, 2018 at 6:20 PM, smf <smf@null.net> wrote: > On 16/07/2018 16:28, Jim Brain wrote: > >> Note that the '816 does not offer an SO pin, and I see no way to emulate >> it on >> the '816 using the CPLD. I will, though, try to route the pin through >> the CPLD >> and optionally connect it when non '816 configuration is selected. >> > > You could route it to the abort input, it's not going to be as fast as it > pushes registers and then jumps to ($ffe8). But you could write code that > sets the overflow flag and returns, so that applications might work. > > > > >Received on 2018-07-17 02:00:18
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