| JWallace |
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Dumb serial computing question
#356482 - 07/14/16 01:46 PM
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So I've been looking into old style serial interfaces, like you would find with hardware buses, and I came across something that I don't understand.
I read in some documentation about the Sony LDP1450 (a serially controlled laserdisc player) that, depending on the baud rate, the commands to be sent can vary, impliying that there's a difference in protocol between different speeds (at 9600 bps a command might take one form, but at 4800 it's something entirely different). Call me naive, but I don't understand why that would be the case for any implementation of a serial protocol, as surely it's the same data just sent at different speeds.
Does anyone have any insight as to what could cause an apparent change in a command along these lines? I just can't grasp it and it's bugging me.
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Re: Dumb serial computing question
[Re: JWallace]
#356623 - 07/18/16 06:22 AM
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Backwards compatibility. There's some older devices that runs at one of the baud rates, so when it detects that baud rate it emulates the protocol of the older devices. When it detects the other baud rate it uses its native protocol.
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| JWallace |
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Re: Dumb serial computing question
[Re: Vas Crabb]
#356629 - 07/18/16 11:35 AM
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So it's basically doing something different to the 8-N-1 setup, because things are a bit noisier? That's going to be fun given how many things run off the same pair of ACIAs in the hardware I'm looking at...
Thanks for your help, I just couldn't figure out what was going on, the whole hardware setup is a bit of a clown car, and different international distributors seem to configure the link in different ways for what is ostensibly the same hardware, purely to get around 50Hz/60Hz PSU issues.
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