com20020-5 Standard Microsystems Corp., com20020-5 Datasheet - Page 2

• Manufacturer Part Number: com20020-5
• Description: Com20020-5 Ulanc Universal Local Area Network Controller With 2k X 8 On-board Ram
• Manufacturer: Standard Microsystems Corp.

FEATURES ......................................................................................................................................................................... 1
GENERAL DESCRIPTION ................................................................................................................................................. 1
PIN CONFIGURATION ....................................................................................................................................................... 3
DESCRIPTION OF PIN FUNCTIONS ................................................................................................................................ 4
PROTOCOL DESCRIPTION .............................................................................................................................................. 8
SYSTEM DESCRIPTION .................................................................................................................................................. 12
FUNCTIONAL DESCRIPTION ......................................................................................................................................... 18
OPERATIONAL DESCRIPTION ...................................................................................................................................... 41
ERRATA SHEET ............................................................................................................................................................... 57
For more details on the ARCNET protocol engine and traditional dipulse signalling schemes,
please refer to the ARCNET Local Area Network Standard, available from Standard
Microsystems Corporation or the ARCNET Designer's Handbook, available from Datapoint
Corporation.
For more detailed information on cabling options including RS485, transformer-coupled RS-
485 and Fiber Optic interfaces, please refer to the following technical note which is available
from Standard Microsystems Corporation: Technical Note 7-5 - Cabling Guidelines for the
COM20020 ULANC.
80 Arkay Drive
Hauppauge, NY 11788
[phone]
FAX [phone]
NETWORK PROTOCOL ............................................................................................................................................. 8
DATA RATES ............................................................................................................................................................... 8
NETWORK RECONFIGURATION .............................................................................................................................. 8
BROADCAST MESSAGES .......................................................................................................................................... 9
EXTENDED TIMEOUT FUNCTION ............................................................................................................................. 9
LINE PROTOCOL ....................................................................................................................................................... 10
MICROCONTROLLER INTERFACE ......................................................................................................................... 12
TRANSMISSION MEDIA INTERFACE ...................................................................................................................... 15
MICROSEQUENCER ................................................................................................................................................. 18
INTERNAL REGISTERS ............................................................................................................................................ 18
INTERNAL RAM ......................................................................................................................................................... 30
SOFTWARE INTERFACE ......................................................................................................................................... 30
COMMAND CHAINING .............................................................................................................................................. 35
RESET DETAILS ........................................................................................................................................................ 37
INITIALIZATION SEQUENCE .................................................................................................................................... 38
IMPROVED DIAGNOSTICS ...................................................................................................................................... 38
OSCILLATOR ............................................................................................................................................................. 40
MAXIMUM GUARANTEED RATINGS ....................................................................................................................... 41
DC CHARACTERISTICS ........................................................................................................................................... 41
TIMING DIAGRAMS ................................................................................................................................................... 45
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