User`s guide

Aironet Wireless Communications, Inc. 5-2 Confidential and Proprietary
Configuration Options register (COR) does not need to be written to access the card. All other interface
registers act the same. All signals and timings are the same as in PCMCIA mode except that the sense of
the interrupt line becomes active high in ISA mode.
In ISA mode, the PC4500/4800 requires external hardware to determine the IRQ and I/O base address that
the card uses. The main requirements are the decoding of the upper address lines to generate a chip select
and route the interrupt line to the desired interrupt. IOIS16# is always decoded as the cards can always
respond to 16-bit accesses. The difference for ISA mode, is that the ISA bus requires this signal to be wire
or’d with the signals from other cards on the ISA bus. This requires that an open collector gate be used.
The PC4500/4800 has an onboard reset controller which insures that the radio comes up properly after +5V
is applied to the card. However, this does not preclude the use of an external reset circuit.
The following diagram illustrates the use of the PC4500/4800 in ISA mode.
ISA_AD[15:6]
ISA_SBHE
ISA_A[0]
PCMCIA_CE1#
PCMCIA_CE2#
ISA_IOCS16*
PCMCIA_IOWR#
PCMCIA_IORD#
ISA_AEN
ISA_IOWR*
ISA_IORD*
ISA_INT
PCMCIA_IREQ#
The LM4500 and LM4800 invert the interrupt
line in ISA mode. The ISA int signal is active
high, the PCMCIA IREQ# signal is active low.
PCMCIA_D[15:0]
PCMCIA_AD[5:0]
ISA_D[15:0]
ISA_AD[5:0]
The LM4500/4800 will only drive 4mA on the
data bus. So, for some applications,
external bus drivers may be required.
The desired 64 byte address block must be
decoded by external hardware.
EN
Upper Address
Decode
ISA bus signals
LM4500/4800 pcmcia
signals
PCMCIA_VPP1
PCMCIA_VPP2
gnd
+5vdc