From: Thomas Huth <1895363@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1895363] Re: borland IDEs double up cursor key presses (need timing on PS2 port input)
Date: Thu, 27 May 2021 05:01:28 -0000 [thread overview]
Message-ID: <162209168868.5770.11350043337385748832.malone@chaenomeles.canonical.com> (raw)
In-Reply-To: 159987499082.17652.11658819873688678558.malonedeb@soybean.canonical.com
The patch mentioned by Philippe has now been merged to the QEMU master
branch (commit d1e45668d2128b064). Michael, could you maybe check the
current git version to see whether this problem has been fixed now?
** Changed in: qemu
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1895363
Title:
borland IDEs double up cursor key presses (need timing on PS2 port
input)
Status in QEMU:
Fix Committed
Bug description:
Most DOS-era IDEs from Borland (I have tried Borland C++ 2.0, Borland
C++ 3.1 and Turbo Pascal 7.1) exhibit strange responses to the
keyboard. Cursor keys are registered twice, so each press of a cursor
key causes the cursor to move twice. Also the other keys occasionally
are missed or duplicated.
From an internet search, the problem appears to be this. These
programs read the PS2 input register multiple times per incoming byte,
on the assumption that the byte will remain there for at least a few
hundred microseconds, before the next byte (if any) appears there.
qemu treats a read of the register by the guest as an acknowledgement
of the incoming byte and puts the next byte into the register
immediately, thus breaking the programs that expect each successive
byte to stay in place for a while.
The obvious solution is to use a timer to advance through the queued
bytes.
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next prev parent reply other threads:[~2021-05-27 5:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-12 1:43 [Bug 1895363] [NEW] borland IDEs double up cursor key presses (need timing on PS2 port input) Michael Slade
2020-09-12 23:48 ` [Bug 1895363] " Michael Slade
2020-09-13 0:08 ` Michael Slade
2021-05-06 6:21 ` Philippe Mathieu-Daudé
2021-05-09 13:56 ` Thomas Huth
2021-05-27 5:01 ` Thomas Huth [this message]
2021-08-25 7:15 ` Thomas Huth
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