tty and video displays

Stan Sieler sieler at
Mon Dec 14 22:27:46 CST 2020

Paul writes:

>  General overstrike requires a bitmap display, or some sort of persistent

Although he carefully specified 'general overstrike', I'll still mention
how the HP 2641A (an APL terminal) did it.   When about to enter a newly
received character into memory, the terminal checked if a non-blank was
already in that spot ... if yes, it looked up the pair in an internal ROM
table and replaced the existing character code with a new character code
designed for APL\3000 (a code that, when received, would display as the
appropriate overstrike).

That meant that we couldn't use the terminal at Burroughs, because our APL
had a few overstrikes that weren't in the table.


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