External Serial Ports
A National Semiconductor PC87336 chip is used to implement the two standard PC COM ports.
These COM ports are compatible with the standard 16450 and 16550 architectures. They are
labeled COM A and COM B and may be configured for any of the following ports:
• COM1 (I/O address = 3F8-3FF, IRQ4) (COM A default)
• COM2 (I/O address = 2F8-2FF, IRQ3) (COM B default)
• COM3 (I/O address = 3E8-3EF, IRQ4)
• COM4 (I/O address = 2E8-2EF, IRQ3)
The serial ports cannot share the interrupts with other devices. The COM3 and COM4 I/O
addresses are used for the touch screen controller, but a different IRQ is used.
Printer Port
A National Semiconductor PC87336 implements a standard PC parallel printer port. The port
meets the IEEE 1284 specification and supports ECP and EPP modes.
Floppy Disk Drive Port
The National Semiconductor PC87336 implements a PC floppy disk port which will support one
floppy disk drive. The port in12 V and +5 V to power the disk drive, which will be cur-
rent limited by Raychem Polyfuses to 1 A max. The connector for this port is unique to the Clean
Screen, so a Planar supplied drive with custom cables should be used. Only pre-formatted
diskettes should be used.
Sound Blaster Compatible Sound System
Sound Blaster
™
compatible sound is provided by an ESS ES1688 sound controller using built-in
speakers or through a 3.5 mm miniphone jack for headphones ranging from 32–300
Ω
. 3.5 mm
miniphone jacks are also provided for stereo line-level input and monaural microphone input.
When a headphone is plugged into the jack the internal speakers will not be driven.
Optional Resistive Touch Screen Controller
Optional touch screen support is provided by an ELO TouchSystems E271-COACH
™
controller.
If your Clean Screen has a touch screen, please refer to the manual included with the touch
screen drivers. An on-board interface to resistive touch screens is incorporated into the CPU
board, emulating a ELO TouchSystems E271-2201 PC-bus controller. This is accomplished by
using the ELO TouchSystems E271-COACH serial controller directly connected to a 16C552
UART. The COM port address and IRQ can be set via software as a standard COM port
(COM1, 2, 3 or 4), using IRQ3, 4, 5, 7, 9, 10, or 11.
Thermostatic Switch/Temperature Sensor
An Analog Devices AD22105 thermostatic switch supports the temperature sensor circuit on the
main board to allow the system to be shut down in an over temperature condition. The switch is
used to detect when the internal ambient air exceeds approximately 50°C (±3°C). When the tem-
perature exceeds 50°C the BIOS will place the Pentium
™
processor in a Standby mode. The Over
Temperature Error fault can only be cleared by entering the BIOS Setup during power-up (refer
to Chapter 5: BIOS Setup, Exit Menu). The switch has a built in hysteresis of approximately
4°C to prevent rapid thermal on/off cycling.
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