[TUHS] More ruminations on terminals

[Paul Winalski via TUHS]

On Thu, May 21, 2026 at 10:00 AM Ron Natalie via TUHS <tuhs at tuhs.org> wrote:

> While the Model 33 could return the type element to the left in the time
> it took for the next 110 baud character to come around, other printers
> required addition of delays in the tty driver to accomodate this.


A Teletype Model 33 actually took two character times to complete a
carriage return.  The most common way to do perform a newline operation was
the sequence CR/LF/NUL.  Not doing this risked the next character being
printed in the wrong column.


>  The
> later Decwriters had the ability to catch up (in addition to printing in
> both directions).
>

The LA36 DECwriter II did this, although it was unidirectional.  It could
print steadily at 300 baud without the need for fill characters.  There was
a circuit board hack to cause the LA36 to print in catch-up mode all the
time.  If XON/XOFF protocol was enabled in the OS's terminal driver, this
allowed the LA36 to operate at double the normal baud rate.  DEC field
service discouraged use of this hack because it dramatically increased the
wear-and-tear on the hardware.

-Paul W.