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Thread: RS232 troubles on the Teletek FDC-1

  1. #1

    Default RS232 troubles on the Teletek FDC-1

    Hi

    I have my S100 box all up and running CP/M, but I now need to start trasferring stuff onto it. Here is the setup:

    • I have a terminal plugged into serial port 0 and a PC plugged into port 1
    • I use Teraterm (on the PC) to send and receive files to/from the FDC-1. The terminal is the CP/M console CON: .
    • The FDC-1's ports implement hardware handshaking, but the terminal (a Wyse 90) doesn't do this very well, so I have had to wire CTS/RTS and DTD together per the Teletec manual. On the console, this works really well.
    • On port 1, it is wired with a null modem adapter. I don't know exactly how this is connected but it must also be crossing the handshake lines.
    • I can send and receive text via port 1 (or 0) but there are problems on sending - occasional dropped characters.


    What I am trying to do is bootstrap our old friend Kermit, using PIP and RDR: to pull in the hex files. The CPSKER.HEX file is split into smaller files so that each piece is small enough to be received without filling PIP's buffer (disk access would cause dropped characters as it has no hardware flow control). As I said, I lose a character here and there for no obvious reason, and as I'm sending hex files this means I can't rebuild the executable.

    I tried at 300 baud and still had the problem. I know, it's that old chestnut again (serial interfacing)! I lost track of the number of times I've wondered why it has to be so hard.

    Any suggestions?
    Last edited by JonB; April 10th, 2019 at 05:45 AM.

  2. #2
    Join Date
    Jan 2010
    Location
    Central VA
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    Default

    I usually customize a version of Mike Douglas's PCGET for systems on which I have no other serial transfer software. Here's his version for the North Star Horizon:

    http://deramp.com/downloads/north_st...n/pcget_pcput/

    The Horizon implementation can use either the console port ("left serial port" on a Horizon) or the other serial port ("right serial port"). You can PIP it in through the console, using a modern computer with terminal emulator software. Just set a pacing delay in TeraTerm. Once PCGET is across, you can usually operate at full speed with no dropped characters, and XMODEM should catch any errors on a simple direct serial link.

  3. #3

    Default

    I can't transfer anything reliably. It's dropping characters even at 300 baud with PIP. I managed to get the PCGET.HEX file across but it doesn't work because the ports are wrong. Moreover the ASM file says it is for the 8251 chip, but the Teletek uses a Z80 SIO to implement the ports.

  4. #4
    Join Date
    Jan 2010
    Location
    Central VA
    Posts
    4,380

    Default

    Quote Originally Posted by JonB View Post
    I can't transfer anything reliably. It's dropping characters even at 300 baud with PIP. I managed to get the PCGET.HEX file across but it doesn't work because the ports are wrong. Moreover the ASM file says it is for the 8251 chip, but the Teletek uses a Z80 SIO to implement the ports.
    Yeah, you'll have to customize it for your hardware.

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