rec.autos.simulators

Wheels use too much CPU!!!

Julian Taylo

Wheels use too much CPU!!!

by Julian Taylo » Thu, 04 Jun 1998 04:00:00

But is the PDPI worth the USD 125 price when compared with Thrustmasters ACM
card or CH's game card which sell for around $25-$30?
Whats the difference?

Trip

Wheels use too much CPU!!!

by Trip » Thu, 04 Jun 1998 04:00:00




> > But is the PDPI worth the USD 125 price when compared with Thrustmasters ACM
> > card or CH's game card which sell for around $25-$30?
> > Whats the difference?

> The PDPI is a digital gameport while CH and Thrustmasters are not.What this
> means is that the PDPI should help out with your framerates if it does what
> Ive heard.Right now I have a P200 with Voodoo2 and GPL runs smooth enough at
> 1024by768 with a joystick.But when I go to my T2 the framerates take a
> dive.Driving a well made simulation like GPL with a joystick is not fun at
> all.I feel so disconnected to my wheel and tires on screen that I switched
> back to my wheel even with the slower fps.They also say that the PDPI is more
> accurate.

I've used the PDPI for a while now and for flight sims, it's easily the
best gameport I've ever owned. It's absolutely rock solid, no drift or
jitters ever, and the control is so precise and repeatable that I almost
feel like I'm cheating.


gameport, but only for Win95 native titles. Any DOS based title will
cause it to fall back to a standard gameport emulation mode. The problem
with Nascar2 is that for some reason, the standard emulation mode dies
when MAscar2 tries to read the gameport. Mike at PDPI told me that the
PDPI can be tripped out of emulation mode by writing a certain value to
the gameport, and I'm assuming that Nascar2 does this.

The PDPI does have a small switch on it that disables digital mode and
forces it to stay in analog emulation, and Nascar2 DOES work with the
PDPI when this switch is activated, but then the PDPI is effectively
nothing more than a $125 analog gameport in that mode, and not a very
good one either. The gameport on my old Soundblaster 16 feels smoother
than the PDPI in forced analog emulation.

For Win95 native titles, i'd say the PDPI is easily the best gameport
you'll find, and well worth the $125 price tag, but if you're thinking
of Nascar2, then you'd probably be best off with a $30 CH Gamecard3
Automatic, in my opinion, the CH is the best of the analog gameports
hands down.

Trips

Geoff Smit

Wheels use too much CPU!!!

by Geoff Smit » Fri, 05 Jun 1998 04:00:00



>Go to the Recent Articles section at the bottom of the page, and read
>the article on the L4 Digital Gameport.

Speaking of things digital, has anyone tried and analog to USB converter?

Specifically a Ymouse product,  I saw at Comdex last year,
it's also cheaper than the L4  digital gameport at $59.95.

http://www.ymouse.com/whitepages/usb-pr.html

I'd be really interested to know if anyone has a USB joystick and what the
CPU usage is
on a USB is,  as well as any compatibility issues.

Regards
Geoff

Trip

Wheels use too much CPU!!!

by Trip » Fri, 05 Jun 1998 04:00:00


> Hi...does the PDPI require a PCI slot or an ISA slot? Thanks

The PDPI is an ISA card, but there may be a PCI version sometime in the
future.

Trips

David G. Marti

Wheels use too much CPU!!!

by David G. Marti » Fri, 05 Jun 1998 04:00:00



> > If anyone knows of a supplier, please post that
> > information.

> > David Martin

> Why not buy the good pots right from TSW?

> Trips

Can you elaborate?  What does "good" mean?

If TSW sells 100K Ohm pots then just say so.

David Martin

Trip

Wheels use too much CPU!!!

by Trip » Sat, 06 Jun 1998 04:00:00



> >   Yes, that's right. The wheels is connected to the game port which in turn is
> > connected to an AD-converter. As we all know, an AD converter does not use more
> > time sampling the high values than the low values. This means the AD converter
> > spits out samples many thousand times a second no matter how big the input values
> > are... This in turn means that the CPU should get its digital data from the game
> > port without any kind of delay.

> > This, finally, should mean that a high value pot
> > should not slow the framerate like someone claims here... If the framerate drops,
> > there must be another reason!

> Well spotted that man! I'd been following this thread, but (obviuosly)
> not closely enough!

> So, come on, people who think that a 200k pot will cause more slowdown
> that 100k, how is this possible?

Read my response to the above quoted post. It's definitley possible.

Trips

Jim Sokolof

Wheels use too much CPU!!!

by Jim Sokolof » Sat, 06 Jun 1998 04:00:00


>   Yes, that's right. The wheels is connected to the game port which
> in turn is connected to an AD-converter. As we all know, an AD
> converter does not use more time sampling the high values than the
> low values.

That depends on the design of the A to D. Most (all?) modern IC's that
do A-D conversions are able to complete a sample of arbitrary voltage
within the rated timestep (thus, at the outputs, they don't take any
longer to read a high resistance).

However, A-D as implemented in old analog game ports (using a polling
routine to time an RC circuit with fixed capacitance) do indeed take
longer to sample a high resistance than a low resistance...

---Jim

asgeir nes?e

Wheels use too much CPU!!!

by asgeir nes?e » Tue, 09 Jun 1998 04:00:00

Where can these RC circuit joystick ports be found? I guess, if you have
one of these, it should be quite wise to invest in a new game port of some
kind...

How many times does a racing sim program check for values on the analog
port? How important is it to have a fast AD system?

How does a RC circuit hoystick port work? It seems to me that it involves
sending a variable frequency signal through the RC circuit and then seing
when the circuits yields some kind of threshold impedance. To me, this
seems like a very hard way to get to the design goals (enabling a variety
of devices to be used...). I guess the circuit must scan over a much
larger area when the high resistance is used, and this does indeed take
time...

---Asgeir---



> >   Yes, that's right. The wheels is connected to the game port which
> > in turn is connected to an AD-converter. As we all know, an AD
> > converter does not use more time sampling the high values than the
> > low values.

> That depends on the design of the A to D. Most (all?) modern IC's that
> do A-D conversions are able to complete a sample of arbitrary voltage
> within the rated timestep (thus, at the outputs, they don't take any
> longer to read a high resistance).

> However, A-D as implemented in old analog game ports (using a polling
> routine to time an RC circuit with fixed capacitance) do indeed take
> longer to sample a high resistance than a low resistance...

> ---Jim

Jukka Hal

Wheels use too much CPU!!!

by Jukka Hal » Tue, 09 Jun 1998 04:00:00


>It's not in the A to D conversion, it's in the actual reading of the
>stick position that the delay is introduced. Analog gameports read the
>stick position by charging up a set of capascitors and then discharging
>them through the stick potentiometers, measuring the time it takes for
>the caps to discharge. The higher the pot value, the longer it takes to
>discharge the capacitors, thus the delay.

>When the gameport is polled, it charges the capacitors and begins the
>discharge. Until the capacitors are discharged, there is no analog
>information to be converted to digital. There's the delay.

All this talk about digital gameports, and so far I haven't seen
anyone mention that it is possible to use even current
'analog gameports' digitally. The catch is you need a different kind
of stick/controller then. MS Sidewinder Pro and Precision Pro can be
used with plain vanilla 'analog gameports', and the
gameport/controller is still read digitally, giving it all the same
benefits as buying a digital gameport.

So it appears to me there are currently two different ways of
achieving this superior digital mode for controllers: either buy a new
digital gameport and keep your old controller, or buy a new digital
controller and keep your old gameport. Pick your poison.

Jim Sokolof

Wheels use too much CPU!!!

by Jim Sokolof » Tue, 09 Jun 1998 04:00:00


> Where can these RC circuit joystick ports be found? I guess, if you
> have one of these, it should be quite wise to invest in a new game
> port of some kind...

All of the $20 game ports (and most of the soundcard ports) are like
this. Basically, if it works with old DOS games without some special
driver, that's how it works.

Between 5-6 Hz on the low side, to 15 for N1/2 and ICR1/2, higher for
GPL. I don't think anyone is doing it more than 100 times a second,
probably no one more than 50.

Discharge the cap by writing to the port. From there, continue to poll
the port until the cap has charged up enough to break over to
true. The number of times you sat there and polled (or the delta in
the RDTSC count) is the value. The lower the resistance on the
joystick, the lower the count; the higher, the higher.

No, it's more like a 555 circuit, where you discharge and then charge
to a threshold, counting the time it took.

---Jim

Trip

Wheels use too much CPU!!!

by Trip » Tue, 09 Jun 1998 04:00:00


> Where can these RC circuit joystick ports be found?

Nearly every gameport out there is an RC (resistor-capacitor) type.

The better ones like the CH and TM cards are adjustable, but they still
discharge a bank of capacitors through the pots in the sticks to get
their readings.

Trips


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