Subject: Re: HP
From: avenar_j@epita.fr (Jean-Yves Avenard)
Newsgroups: hpcalc.general
Organization: unavailable
Date: Jan 04 2001 15:09:28
User-Agent: Microsoft Outlook Express 5.50.4133.2400

Ok..

On y va donc...

"5.4.5 RSI Instruction
The RSI (ReSet Interrupts) instruction resets the KDN interrupt state
machine. After an RSI is executed the CPU will interrupt immediately if KDN
is high and interrupt processing is enabled (INTON and RTI). If KDN is high
and interrupt processing is disabled, the CPU will interrupt as soon as
interrupt processing is enabled (INTON and/or RTI). This bypasses the need
for KDN to go low before a new interrupt can be generated.
The RSI intruction should be used prior to RTI when keyboard scanning shows
no keys are down. This will detect keys that are depressed between the time
of last scan and the RTI by causing an immediate reinterrupt"

A propos de KDN...
"5.4.4 KDN Interrupts
KDN line - rising edge sensitive with qualifications - see text.
KDN is the "logic OR" of IR15X (ON) and the IR[0:8] lines. IR[0:8] lines
held high will generate only one initial interrupt and will not repetitively
reinterrupt the CPU as do the NINTX, NINTX2 and IR15X lines (note du copiste
JYA:IR15X = ligne ON, NINTX et NINTX2 entrees du processeur).
IR[0:6] interrupts are maskable using the INTON and INTOFF instructions
A rising edge of KDN will generate an interrupt if the CPU is outside of the
interrupt routine (RTI) and interrupts are ON (INTON). Once this interrupt
has occured, no further KDN interrupts can occur until another rising edge
of KDN occurs of the interrupt routine with interrupts ON or until both RTI
instruction and an RSI instruction (see below) have been executed.

A rising edge of KDN will occur if IR[0:6] and IR15X were all momentarily
low and if: 1)a rising edge occurs on IR15X; or 2)one or more of the IR[0:6]
goes high.

The interrupt state machine ignores edges on KDN (and does not latch a
request for a new interrupt) while the CPU is in the interrupt routine. This
allows software to scan the keyboard by setting each OR line high in
succession and executing an A=IN or C=IN without latching the need for
another interrupt. During this keyboard scanning, KDN may be toggling low
and high based on the keys that are down and the OR line that is high. In
order to avoid "spurious" interrupts, software must ensure that the KDN
signal has been updated to match the current state of the keyboard-OR lines
before exiting an interrupt routine where keyboard scanning has occured.
This is normally done by restoring all keyboard-OR lines to their normal
state using OUT=C or OUT=CS prior to the RTI. This ensures that if any key
is down the KDN signal will be HIGH when the RTI is executing"

Bon voila, y'a tout la dedans sur comment marche les interruptions claviers.

A+
Jean-Yves