On Fri, 17 Mar 2000, Fred Wright wrote:
> > I forgot to mention that the actual connection in this case was at 57600
> > bps. The 1200 has no trouble routing between the serial port and the
> > ethernet at this speed. Yet the 1200 has a 50 MHz 68060 and can't do
> > 115200, while the 3000 with the original 25 MHz 68030 can (at least when
> > there's no ethernet).
> CPU power isn't the main issue. Contention for custom chip sccesses is.
> People often forget that accessing chip *registers* is just as expensive
> as accessing CHIP *RAM*. Every interrupt needs to do it, every Disable()
> or Enable() needs to do it, etc. With a maxed-out native display, a
> single custom-chip access can take over 50 microseconds. Compare this to
> the requirement to service the serial port every 87 microseconds at
> 115.2K to avoid character loss.
Yes, but as far as I know 2 bitplanes on the 3000 takes as much DMA
bandwidth on the 3000 as 4 bitplanes productivity (my Workbench) on the
1200. It's a long time ago I played around with this, but I don't remember
getting 115200 bps to work reliably in any screen mode, even with all kinds
over vector base moving going on. I guess the 3000 design is still superior
in some ways to the newer AGA stuff.
Such a shame it all ended in 1992, I can't imagine what an Amiga-based
machine could do with all the new hardware and software that's available
today. I hate to say it, but getting a PC sure did make my life easier.
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