Hi John,
Regardless of how disappointed you are on the resulting speed I think
you have done a great job in producing a java emulation for the QL. At
very least it makes it easier for people to try the QL.
Well I'm not that disappointed really at the difference in speed with
QPC. What baffles me is that this difference seems to vary so much from
machine to machine.
Some here have reported of sufficient speed, whereas others (e.g. Bob
Spelten, Ian Burkinshaw) reported a totally useless emulation because of
its slow speed. Moreover, how come a 2+Ghz machine is so much slower
than, say, a Raspberry Pi (even though that, also, is too slow to be
useful.?
Id like to hear more about Bob's machine : is it also a single core like
I think Ian's is?
The java emulations are going to be slow because the Java virtual
machine is slow
Sorry, but no.
(And please, let's NOT open that debate)...
Mainly, SMSQmulator is slow because:
1 - I'm trying to to things with Java for which is wasn't really
designed (painting single pixels to a "screen", low level byte,word
access to variables and memory, etc).
2 - The emulation core isn't necessarily designed for speed.
3 - I'm by far not the programmer Marcel is.
As the java machine has a built-in garbage collector timings are going
to be erratic as the whole java machine suddenly stop while it does the
garbage collection.
Perhaps, but I doubt it. I've yet to see such a phenomenon.
Would it be possible to increase the speed of the emulation if the
keyboard was only checked as often in time as the standard QL does?
The "machine" only has one single interrupt - a 50 Hz interrupt, just
like the QL. There is no way to make that any slower, else things (like
the clock) will go wrong etc. Even the keyboard doesn't generate an
interrupt as such (so if you could type faster than 50 chars per second,
some would get lost...)
Could this also be done for the display?
Well, drawing to the screen is heavy on the resources, ESPECIALLY when
one is in QL compatible mode. Basically, I redraw the ENTIRE screen once
for every pixel changed (or every 2 or 4 fixels in QL mode).
If anyone could point me to a way to change a wingle pixel in a window
I'd be grateful...
(...)
So carry on the good work and bask the glory having done it.
Thanks for your kind words.
Wolfgang
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