Re: What specs would your Apple ][ clone have today?

["sicklittlemonkey" <Nick.Westgate@gmail.com>]

On Apr 9, 1:20 am, "biel...@terra.es" <R2DTh...@gmail.com> wrote:
> Did you rely on 65Host for 6502 emulation, or you wrote your own 6502
> emulation code instead ?

My co-author, Sean Fausett, wrote the CPU.

> Do you recall how many (arm) instructions did it take (more or less,
> or on average) to emulate a 6502 opcode ?

Well, you have the source now. Taking a quick glance it looks like
even simple 6502 instructions took about 20 ARM instructions! Most of
that is overhead for maintaining sound output, cycle counting, an
event queue, bank-switched memory. On average it's more, since the
event queue triggers off things like video refresh, paddle events etc.

> Things like
> if(Z) then R1=R2+(R3*4) -->> EQADDS R1,R2,R3,LSL #2
> Conditional-execution... lovely ARM things !

Yeah, it's a lot of fun. Wonderful for writing a compiler, but not
directly applicable in a magic way to _generic_ emulation as such.

Anyway, I hope you find the source interesting.

Cheers,
Nick.