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

[Rick Murphy]

At 09:04 PM 5/13/2009, Philipp Hachtmann wrote:
>Hi,
>
>>I completely mis-understood the source of your troubles.
>Oh.
>The VT05 terminal operates at speeds from 110 baud to 2400 baud, 
>selectable with a rotary switch in the back (my unit is currently 
>missing a counter ic to generate 110baud, but...).
>So far so good. The problem is, that when you want to operate the VT05 
>at speeds higher than 300 baud, you have to wait a certain amount of 
>time after a line feed character or cursor positioning command. This 
>is usually done by inserting zero fill characters (4 at 2400 baud) 
>after the critical commands. If you don't obey this rule, the VT05 has 
>not completed changing the line when you send the next character. This 
>is a bit like a too slow cr on a teletype - funny but true.
>So my wish was to modify OS/8 so far that it generates those fill 
>characters.

As I said earlier, this is easier said than done. However, it's 
possible if you've got source and the time. Fitting something that does 
the job into the CD and KBM is hard given how tight this code is.

>The TTY: handler is also capable of correctly doing this for me. But 
>many other programs - as the OS/8 keyboard monitor itself - use direct 
>IO commands to read from and write to the terminal.
>So one would have to patch many programs. In case of the keyboard 
>monitor, I don't know if there is any room left to put such a code in. 
>And I don't know how to reassemble and correctly install a new 
>keyboard monitor from scratch.

Assemble? Just use PAL to assemble KBM and CD, then use the BUILD 
program to load it. You load the new KBM and CD .BN files using the 
BUILD command (within BUILD). It'll prompt you for the location for the 
OS8.BN and CD.BN files. Unfortunately, using BUILD will zero the 
directory on the target device, so you had better be sure that's what 
you want to do. :-)
         -Rick