tty and video displays

Paul Koning paulkoning at
Mon Dec 14 08:28:48 CST 2020

> On Dec 14, 2020, at 9:26 AM, emanuel stiebler via cctalk <cctalk at> wrote:
> On 2020-12-14 05:41, Brent Hilpert via cctalk wrote:
>> On 2020-Dec-14, at 1:26 AM, ben via cctalk wrote:
>>> Often for data input one could use over strike characters for input. Not EQ might be = BS | Did any video display terminals
>>> repeat the same effect?
>> Yes. Coincidentally I've just been refurbishing one - a Teleray 3931.
>> It's an ASCII/APL terminal, overstriking was included for the APL mode.
>> Note the screenshots in APL mode.
> Is it really an overstrike? They look simply like different characters.
> At least, I didn't (probably missed it) how they can be generated out of
> the available ones...

I wondered too.  General overstrike requires a bitmap display, or some sort of persistent display.  Paper is an example; a Tek 4010 would also handle overstrike since it uses a storage tube.  And PLATO terminals did overstrike just fine since they are bitmap displays with per-pixel memory.


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