Hardware manual

3 Programmers Reference EUROCOM-17-5xx
66 Hardware Manual
On default setting, the system CIO, user CIO and the CL-CD2401 are
routed to the same IRQ level (LIRQ6) of the VIC. The CL-CD2401 has
the highest priority.
A special feature of the EUROCOM-17-5xx is the programmable
interrupt level of the CIOs and the graphic frame interrupt. So, the CIOs
can be routed to an other interrupt level as the serial controller
CL-CD2401.
The CIO interrupt level register (at address $FEC5.4001) allows to route
the CIO interrupts to LIRQ6 or LIRQ4. Routed to LIRQ4, the VIC must
be programmed to supply the vector and to generate the desired interrupt
level for the CPU.
The CL-CD2401 is always routed to the LIRQ6 of the VIC.
Table37: SCIO, UCIO Interrupt Level Register
X don’t care
FR Frame interrupt request
UCIO User CIO interrupt
SCIO System CIO interrupt
Table38: Interrupt Level Assignment for SCIO, UCIO and FR
Example:
D7 ... D0
XXXXX 1 0 1
routes the system CIO to LIRQ4. So, the VIC must supply the IRQ vector.
The user CIO is routed to LIRQ6 and the frame interrupt capability is
disabled.
Address D7 - D0
$FEC5.4001 X X X X X FR UCIO SCIO
(Default 0 0 0 )
LIRQ4 LIRQ6 Disabled
FR 0 - 1
UCIO 1 0 -
SCIO 1 0 -