10
4-PORT CARD SERIAL HOST ADAPTER WITH ISP
2.2 Technical Description
The IC102C-R2 Adapter uses the 16554 UART. This chip features programmable
baud rate, data format, interrupt control, and a 16-byte input and output FIFO,
and is functionally 4 16550 UARTs. The IC180C uses 16950 UARTs, which feature
a 128-byte FIFO.
This Adapter features:
• Sharable IRQs that allow more than one port to share a single IRQ.
• Support for IRQs 3–7, 9–12, and 15.
• 16554 buffered Quad UART (IC102C-R2) or 16950 UART (IC180C).
• Easier integration with 16-bit address decode.
• Speeds up to 460.8 Kbps.
• Multiple clocking modes that ensure compatibility with existing software
products.
2.2.1 I
NTERRUPT
S
TATUS
P
ORT
(ISP)
The 4-Port Card Serial Host Adapter with ISP provides you with an Interrupt Status
Port (ISP) for greater throughput when servicing multiple ports on a single
interrupt line. The ISP is a read-only 8-bit register that sets a corresponding bit
when an interrupt is pending. Port 1 interrupt line corresponds with Bit D0 of the
status port, Port 2 with D1, etc.
The ISP is located at Base+7 on each port. (For example, Base = 280 Hex, Status
Port = 287.) This allows any one of eight locations to be read to obtain the value in
the status register. All four status ports on the Adapter are identical, so any one of
the four can be read to determine which interrupt is pending. In the example
below, Channel 2 has an interrupt pending.
Bit Position:
7
6
5
4
3
2
1
0
Value Read:
0
0
0
0
0
0
1
0
Содержание IC102C-R2
Страница 3: ...2 4 PORT CARD SERIAL HOST ADAPTER WITH ISP...
