DEC VT05 with OS/8 -- basic system rebuild?

[Vincent Slyngstad]

From: "Philipp Hachtmann"
Sent: Tuesday, May 12, 2009 11:31 PM

> At least the delay I got to work, I think. Since then I can correctly 
> display DIRerctories. But... 
> Read my last message - all that's completely useless :-(

If your concern is the large software base that does something like
    TSF; JMP .-1; TLS
to output a character, then yeah, you'll need hardware line-feed 
delay.  Per the KL8J/M8655 documentation:
"
Fill Characters -- VT05
    To operate at speeds above 300 baud, the VT05 requires 
    that filler characters be transmitted to it followeing 
    any line feed character.  The insertion of the "FIL" 
    jumper on the M8655 causes four all zero characters to 
    be automatically transmitted to the VT05 following 
    every line feed.  The transmit flag is not set until 
    the KL8-JA is ready to accept other data.
"
There doesn't seem to be any equivalent provision for the KL8E/M8650,
or (surprisingly) the DKC8/M8316.  So I think your easiest solution 
for an 8/e/f/m/a is to install an M8655.

For earlier machines, the M707 transmitter module has a "wait" input, 
which is designed to hold off a half-duplex line, but which I believe 
could be adapted to do what you want.  You'd have to add a couple of 
chips somewhere (effectively modifying or replacing the M707), though.

If the VT05 dropped DSR or some similar signal during the interval that 
it is not ready, it would make things a lot simpler.  I don't see the 
circuitry to do that in the VT05 schematics, though.

    Vince