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I am intending to purchase a used laptop to handle some instruments via bit banging. I see some have either or both parallel/serial ports and could get one without and ...
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  1. #1
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    Laptop ports


    I am intending to purchase a used laptop to handle some instruments via bit banging. I see some have either or both parallel/serial ports and could get one without and use PCMCIA. I began reading about this and it seems everything is going through the USB yet looking like the aforementioned ports. This will not work for me as I understand there is a 125 ms time frame involved with USB, which will interfere with my bit banged code.
    Can someone assure me there is a way to install true legacy parallel and serial ports in fairly recent laptops?

  2. #2
    tpl
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    depends what you mean by "recent." The ibm thinkpad t23 has both ports,
    as does the a31p. Perhaps you should spell out your CPU/memory/drive
    requirements: are you planning to use a "desktop environment"?
    the sun is new every day (heraclitus)

  3. #3
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    Notice I said intending to buy hence cannot specify hardware. Not for desktop enviro as I have 3 of those available to me. Just looking at the used market for something 3-4 yr old. The USB is becoming not the port of choice but port of provision. One can access printer via cable adapter (& drivers) to have USB-to-Parallel port but this will not allow for me to access the port for microsecond timing due to what I am told is a 125ms frame buffer in the USB.
    Thus are all new laptops constrained to use everything thru the USB or can a regular legacy parallel port be added to these puppies without a USB in the middle???

  4. #4
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    That would be very difficult since you would have to alter the motherboard. I wouldn't even think of doing it without a logic analyzer and oscilloscope. Even then, with multi-layer motherboards it may turn out to be impossible to splice into the traces you will need to. At the very least, this would be a long-term project.
    Registered Linux User #420832

  5. #5
    Linux Guru Rubberman's Avatar
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    If the laptop you get doesn't have serial/parallel ports (a lot still do have them, such as the Dell Latitude series), then your best bet is a PCMCIA card with them.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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