HFC-U Cologne Chip AG, HFC-U Datasheet - Page 15

• Manufacturer Part Number: HFC-U
• Description: Isdn HDLC Basic Rate Controller
• Manufacturer: Cologne Chip AG

The HFC-U has no memory or DMA access to any component on the ISA-PC bus.
Because of its power drive characteristic it needs no external driver for the ISA-PC bus data lines.
If necessary you can add an external bus driver. In this case the output BUSDIR determines the driver
direction.
3.2
In the microprocessor mode the HFC-U uses 256 I/O addresses (SA0 - SA7).
*)
All registers are directly accessable by their I/O address (see register description).
Except in mode 4 ALE is assumed to be stable after a RESET.
March 1997
1-pulse latches I/O address.
X = don't care
/IOR
/DS
X
1
0
0
0
1
0
1
Processor mode
/IOW
BUSDIR = 1 means that data is driven into the HFC-U;
BUSDIR = 0 means that the HFC-U is read and data is driven to the external bus.
R/W
X
1
1
0
1
0
1
0
/CS
X
1
0
0
0
0
0
0
ALE
0
0
X
X
1
1
0
0
*)
*)
Operation
write data
write data
write data
no access
no access
read data
read data
read data
Mode
all
all
2
2
3
3
4
4
HFC-U
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