TICDUP fixed in 1.4

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John Carmack

Jun 10, 1994, 3:47:28 AM6/10/94
I fixed the ticdup network option today, so all of you working on
multi player serial drivers can use it soon...

For those of you that haven't talked with me about it, the ticdup
field set by the communications driver allows it to tell DOOM to send
less data to the other players. Normally, DOOM tries to send 35
little packets of data a second. Ticdup makes DOOM internally
duplicate the packets, so it will send half, a third, or whatever the
normal number of packets. This results in a slight loss of precision
in control and game smoothness (the max framerate for a ticdup 2 is
17 fps, no matter what speed the computer is), but a great reduction
in bandwidth requirements.

This should help a lot on internet connections, too.

For noisy communications situations, you can also set the extratics
field to 1 to cause DOOM to send an extra command from the previous
packet along with the new packet. This allows a packet to be lost
without forcing a retransmit request. This raises the bandwidth
requirement, though.

If someone writes a direct IP driver for running on the internet,
setting ticdup to 3 and extratics to 1 should allow decent play (12
fps) even over a router hop or two.

John Carmack
Id Software

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