On Wed, 3 Mar 1999, Bob Ebert wrote:
> The new devices are faster because of a bunch of optimizations in the newer
> OS and fewer wait states when accessing memory.
>
> It turns out that overall performance is almost entirely bound by the time
> it takes to fetch instructions and data out of memory. That is, in the
> current architecture the bus is constantly busy. So if you want to go
> faster, in general you have to either use fewer instructions or read &
> write less memory.
Some time long ago (before the EZ was mentioned), I suggested that Palm
ask Motorola to produce a dragonball with a 68EC010 core instead of the
68EC000 in both current models. Besides virtual memory possibilities
(i.e. really have 16 meg of ram), it has the loop mode so that any single
instruction followed by a dbcc locks into the pipeline and there are no
more instruction fetches until the loop terminates. Things like move
(a0)+,(a1)+ would about double in speed.
> Put another way, a faster clock won't help much unless you can also speed
> up the bus, which means speeding up memory. So don't try overclocking the
> CPU. :)
Speeding up the clock shortens the time each wait state takes in equal
proportion. So if you do overclock the CPU (on the newer palms), you
might want to add wait states - which will partially negate the benefit
from overclocking.
Having experimented on my Palm III with TRG SPXL board, my Concorde
program - which I hand optimized the critical routines specifically to
minimize memory access (see www.angelfire.com/mi/tzstuff for source and
executable) given a very long search ("sardonyx" in Revelation 20 from
Genesis 1:1):
2:13 Baseline (Normal Palm III - 3 wait state flash and RAM).
Note: Running from flash in a stock Palm III (Not a TRG SPXL) will
be slightly faster than running from RAM - probably due to
RAM refresh, but I have no way to verify this.
1:42 Code running from flash with 1 wait state.
1:36 3 wait states, Eco Hack 23 Mhz overclock.
1:32 Code running from flash with 0 wait states.
1:16 Eco Hack 23 Mhz and 1 wait state.
Eco Hack at 23Mhz and 0 wait states failed with a dialog box that had
characters that I didn't recognize as belonging to any font :). At 0Ws,
19 Mhz overclock it said "Fatal Exception" and locked up.
Moving the database into flash added about 1% speed improvement, but the
optimization tried to avoid accessing RAM as much as possible.
I will try the P3x and P5 in their stock configurations when they arrive.
WARNING: Don't try this at home. Or in the office. Or on your personal
Palm.
