B&B Electronics ESCLP-100 - Manual - Manual (Page 18)

3.4.2 PCMCIA bus
Quatech multiport PCMCIA serial port cards will share a single interrupt between all
ports on the card. Interrupt sharing between multiple PCMCIA cards is governed by the
PCMCIA subsystem, and is not supported by this device driver.
3.4.3 ISA bus
ISA (AT) bus computers do not support the sharing of hardware interrupts. The nature of
this bus is such that interrupts are easily lost if sharing is attempted. The device driver
overcomes this limitation by using the interrupt status register on certain Quatech non-intelligent
multiport serial adapters. The interrupt status register is required for interrupt sharing on
non-intelligent adapters. Quatech intelligent serial adapters also require only one IRQ. The
driver prohibits any Quatech ISA bus adapter from sharing its IRQ with another device.
3.4.4 Micro Channel Bus
Micro Channel bus computers inherently support the sharing of hardware interrupts.
Although the interrupt status register is not absolutely necessary for interrupt sharing on the
Micro Channel, the device driver can take advantage of its presence for increased performance.
The driver prohibits any Quatech MCA bus adapter using the interrupt status register from
sharing its IRQ with another device. These adapters can share their IRQ if the interrupt status
register is not used. If this is the case, all of the ports on the adapter must be declared
individually as "standard" serial ports (see page 9).
3.5 Baud Rates
All standard baud rates up to 115,200 bits per second are supported for all UART types.
If 16550 UARTs are detected on a Quatech Enhanced Serial Adapter, the maximum baud rate
increases to 230,400 bits per second. If 16750 UARTs are detected on a Quatech Enhanced
Serial Adapter, the maximum baud rate increases to 921,600 bits per second. Actual
performance may be limited by the computer's hardware configuration (CPU speed, free memory,
etc.), cable quality and length, and system software loading amongst other factors.
The driver will refuse to set any baud rate that the hardware cannot achieve within 0.01%,
with the exception of 110 and 2000 bits per second.
3.5.1 High baud rates (> 57,600 bps)
The device driver implements the async IOCTl 0x43 and 0x63 functions for support of
high baud rates. This is the only way for software to set baud rates above 57,600 bps. The async
IOCTl 0x41 and 0x61 functions reject baud rates higher than 57,600.
Quatech Enhanced Serial Adapters use jumper-selectable UART clock input rates. The
factory shipping configuration is a software-programmable mode defaulting to a standard
times-one clock, signified by having the "X2", "X4" and "X8" jumpers removed (there may be
spares installed in neutral positions). On some ISA adapters, there may be a "SW" (software)
jumper installed. The PCI adapters do not use a "SW" jumper.
For baud rates higher than 115,200 bps, the device driver uses the clock rate multiplier
logic found on Quatech Enhanced Serial Adapters. If none of the rate selector jumpers are
applied (see your hardware manual), the driver can set baud rates as high as 230,400 bps for
Quatech Asynchronous Serial Device Driver for OS/2 15