>
> > To the contrary, the Atari 400/800's joystick port delivers data at *VERY*
> > high rates without hacking the hardware. We got 3-5K bytes per second
>
> Tell that to the designers of the XEP-80. I realize that two joystick
> ports were used to drive the Corvus hard drive, but that's not viable on
> the 2600.
Glenn, are you going to make me prove it? I've got enough Superchargers
and 2600's lying around...
If later 2600 models had bypass capacitors on the joystick lines to filter
RFI, there might be a problem with speed. We clipped capacitors on the PC
parallel cards to make them run faster, but those cards were designed to
connect to long, unshielded ribbon cables. Damn, now I have to dredge up
a 2600jr to test with too. <sigh>
The data rate needed for joystick data exchange is 60 * 5 bits/second per
machine. Conservatively, it'd take about 100 cycles to send and another
100 to receive 5 bits during the VBLANK game time. It helps that both
machines run at about the same clock frequency and don't have interrupts,
so handshaking isn't necessary once the two machines lock their VBLANKs
together.
The biggest pain will be building a female-to-female cable and cleaning
out the closet to find a 2600jr.
As long as I'm at it, I'll hook up an LED to bit 5 of the RIOT B port and
settle the COMBAT question once and for all.
Film at 11, or sometime this weekend.
- Jim
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