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Thread: Scripted Time-Delayed Transmission of ASCII Text Characters

  1. #1
    Join Date
    Sep 2011
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    Michigan, USA
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    194

    Default Scripted Time-Delayed Transmission of ASCII Text Characters

    Hi, I am in the process of writing an assembler on a custom homebuilt TTL computer. The computer does not have a CPU. The control logic is hardwired and uses the 74F181 ALUs for math and logic computations. The I/O consists of an APPLE II keyboard keyboard capable of direct ASCII output, primarily capitalized text and numeric chacters. The computer output is simply a PIC microcontoller bus monitor relaying to a serial terminal program running on a laptop. The serial program I am using is called Termite. (I type commands on the APPLE II keyboard, and the text output from the TTL computer shows up on the laptop's screen.) I can easily modify the PIC microcontroller serial relay to both send and receive from the laptop.

    Presently I type the mnemonics for my primitive compiler on the keyboard. What I want to do instead is create a text file and transmit that to the TTL computer. A representative file might look something like this, where (CR) means carriage return.

    MAB(CR)
    ADD(CR)
    INC(CR)
    etc

    This is Move A to B. Add A and B together. Increment A. etc. My assembler source file is getting longer and I prefer to stop typing it in every time.

    What I need is a serial terminal program that can transmit a simple text file, character by character, but slowly. At present my computer is only running at about 200 Hertz. Does anyone know of a serial transmission program that can be set to transmit individual ASCII characters from a text file at a slow pace (~1 per second), including the carriage return? The laptop is running XP, but I could use DOS just as easily.

    Here is a link to my project with some photos. (Scroll down to see the photos.) Thanks, Michael

    http://www.mtmscientific.com/stack.html

  2. #2
    Join Date
    Sep 2014
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    central florida
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    Default

    I use minicom and ascii-xfr

    Minicom is a pretty nice serial terminal program and open source.
    ascii-xfr is a utility provided with minicom and allows up/down load,character delay, newline delay and more.
    I use it frequently for downloading hex object files (ASCII) to the single board computers I play with.

    joe

  3. #3
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    Jan 2007
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    Default

    I read the article, but it gives no indication of what you're using for your serial interface.

  4. #4
    Join Date
    Sep 2011
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    Hi, The Minicom application for Linux looks to be exactly what I described. I see it has two settings that can be adjusted: line_delay and character_delay. If no other DOS or XP suggestions are made I will consider adding a Linux box, or writing something for the XP platform in FreeBASIC that does the same.

    Yes, bad on me for not even mentioning the serial communication on my webpage. I just now added some additional information. It's pretty simple. I am using a Picaxe-20X2 microcontroller programmed in Picaxe Basic to handle sending ASCII characters to-and-fro from the the console. The Picaxe has enough I/O ports to directly handle the 12 bit bus width. The clock speed of the TTL Computer is so slow that I can just monitor the bus with logic and loops to do what is needed.

    Here are a couple of photos. The one photo is the entire setup. You will see that I have the computer and keyboard screwed-down on a piece of wood. I also built a bus expansion riser that you can see has the card for serial communication plugged in. I also included a photo of the serial card here. Thank you everyone for your input. Michael

    serial.jpg

    ttl_setup_s.jpg

  5. #5
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    Default

    It would seem that the Picaxe could manipulate CTS/RTS to throttle the input to whatever you wanted.

  6. #6

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    If you can't use hardware handshake, you can try software hand shake.
    Since you are working on a stack processor, I'm sure you are aware of Win32Forth. I do all kinds of serial with it. I use it to down load ascii text as well as binary data to program things like my Blue Pill. I can type stuff in or transfer from files. If you are not using the obnoxious windows 10, Win32Forth works with older versions easily. On W10, you need to defeat their stupid virus protection.
    Dwight

  7. #7
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
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    Default

    In DOS I use Procomm for this sort of thing.

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