For other machines, the IOCHRDY signal may
be briefly negated to give the device the extra
time necessary to support the faster machines.
Aside from the implementation of a 16-bit data
bus interface, the remaining bus interface logic
is identical to that found in the SMSC
COM90C65, which contains all the support logic
circuitry.
The ARCNET Local Area Network is a token
passing network which operates at a 2.5 Mbps
data rate. A token passing protocol provides
predictable response times because each
network event occurs within a known time
interval. Throughput can be reliably predeter-
mined based upon the number of nodes and
their expected traffic.
The COM90C66 establishes the network
configuration and automatically reconfigures the
token passing order as new nodes are added or
deleted from the network.
The COM90C66 performs address recognition,
CRC checking and generation, packet
acknowledgement,
and
other
network
management functions.
The C0M90C66
interfaces directly to the IBM PC/AT or
compatibles. The internal 2K x 8 RAM buffer is
used to hold up to four data packets with a
maximum length of 508 bytes each.
PIN CONFIGURATION
A19
A18
A17
A16
A15
A14
A13
A12
A11
A10
VCC
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
11 10 9 8 7 6 5 4 3 2 1 84 83 82 81 80 79 78 77 76 75
AEN
D0
D1
D2
D3
D4
D5
D6
D7
GND
D8
D9
D10
D11
D12
D13
D14
D15
INTR
nBSLED
nTXLED
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
BALE
nSBHE
nOWS
IOCHRDY
nMEMCS16
nIOCS16
GND
nMEMW
nMEMR
nIOW
nIOR
nTOPL
nTOPH
NC
NC
CACLK
CLK
RXIN
nPULSE2
nPULSE1
nPROM
COM90C66
33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
XTAL1
XTAL2
NID0
NID1
NID2
NID3
NID4
NID5
NID6
NID7
VCC
IOS2
IOS1
IOS0
MS4
MS3
MS2
MS1
MS0
RESET IN
nENROM
PACKAGE: 84-Pin PLCC
3
Ordering Information: COM90C66 LJP
SMSC [ SMSC CORPORATION ]
