TNC archeology

KR konrad.roeder at
Thu Apr 26 07:18:53 PDT 2018

Ahhh so you were calling one micro-subroutine at a time.  Interesting.

--Konrad, WA4OSH

On Wed, Apr 25, 2018 at 3:26 PM, Curt, WE7U <curt.we7u at> wrote:

> On Wed, 25 Apr 2018, KR wrote:
> In the mid-1980's I wire-wrapped a Z-80 with  Z-80 FORTH running on it.
>> The beauty of FORTH was extremely tight code.  The "atoms" were chunks of
>> machine code.  The more complex code that called called the atoms was
>> simply a string of two byte addresses of the atoms.
> That's where I made my modification. I changed it from two-byte addresses
> to <Call> <Address> <Address> (3 bytes total), then all was directly
> executable and I got rid of the Forth inner interpreter entirely. This made
> it blindingly fast on a 1/4 color-burst frequency clocked microprocessor
> (0.89 MHz). I wrote that Forth over Christmas break from college, so took
> me 2 weeks.
> The code for an entire assembler occupied no more than one page of code.
> Once I had Forth up and running I wrote an NMI handler for a line going to
> the cassette port, put an XR-2211 chip between the computer and a radio,
> and did AX.25 receive plus CRC-16 check into it as Forth words. I had it
> doing 300/600/1200 baud off using a Drake TR-33C crystal 2-meter radio.
> That was my first packet station, receive-only.
> --
> Curt, WE7U.
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Konrad Roeder
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