14 Dec
2020
14 Dec
'20
8:27 p.m.
Paul writes:
General overstrike requires a bitmap display, or some
sort of persistent
display.
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.
Stan
14 Dec
14 Dec
9 p.m.
Now I want to know if you have a list of the Burroughs APL
overstrikes, since HP included many more overstrike characters in the
HP 2641A than the ones that they needed for APL\3000, including (or so
I'm lead to believe) all the Burroughs extended I/O quad overstrikes,
presumably to maximize the market for the terminal and/or because they
thought they might implement the same functionality at some point. So
it would be interesting to know what was actually missing.
The overstrike character ROM for the HP 2641A includes 63 characters,
but (IIRC) only something like 21 are used in APL\3000.
P.S. My HP 2641A emulation will be in the next official MAME release
thanks to F.Ulivi who merged it into his existing HP 2645A driver and
got it submitted upstream.
G.
On Mon, Dec 14, 2020 at 10:28 PM Stan Sieler via cctalk
<cctalk at classiccmp.org> wrote:
That meant that we couldn't use the terminal at
Burroughs, because our APL
had a few overstrikes that weren't in the table.
15 Dec
15 Dec
6:52 p.m.
For these interested on how it looked, I posted a picture of all the characters created by
the HP 2641 APL ROM dumps here: https://www.curiousmarc.com/computing/hp-264x-terminals
(somewhere down in the middle of the page). ROM dumps were from Al Kossow I believe
(thanks Al).
Marc
On Dec 14, 2020, at 9:00 PM, Gavin Scott via cctalk
<cctalk at classiccmp.org> wrote:
?Now I want to know if you have a list of the Burroughs APL
overstrikes, since HP included many more overstrike characters in the
HP 2641A than the ones that they needed for APL\3000, including (or so
I'm lead to believe) all the Burroughs extended I/O quad overstrikes,
presumably to maximize the market for the terminal and/or because they
thought they might implement the same functionality at some point. So
it would be interesting to know what was actually missing.
The overstrike character ROM for the HP 2641A includes 63 characters,
but (IIRC) only something like 21 are used in APL\3000.
P.S. My HP 2641A emulation will be in the next official MAME release
thanks to F.Ulivi who merged it into his existing HP 2645A driver and
got it submitted upstream.
G.
> On Mon, Dec 14, 2020 at 10:28 PM Stan Sieler via cctalk
> <cctalk at classiccmp.org> wrote:
>
> That meant that we couldn't use the terminal at Burroughs, because our APL
> had a few overstrikes that weren't in the table.
1418
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curiousmarc3＠gmail.com -
gavin＠learn.bio -
sieler＠allegro.com