3C523 Etherlink/MC
3C523 Etherlink/MC TP
Late 3C523 Etherlink/MC
Older versions not compatible with 486+
3C523 ADF Sections

3C523 Etherlink/MC TP

Late 3C523 Etherlink/MC

� I found two of these in a 3172 Interconnect Controller. Marked "(C) 1990 3Com" on the front.

IMPEDANCE
����� a.� Use a test device to verify the characteristic impedance of your�
�������� cable from the wiring closet to the station.
����� b.� Choose the setting closest to that characteristic impedance.
��������� Default Setting:� 100 ohms
��������� Alternative Settings:� 75 ohms, 150 ohms

RECEIVE THRESHOLD, LINK BEAT, EQUALIZATION, TRANSMIT LEVEL, and DC SIGNAL jumpers, refer to Table 1.�

�Table 1.� Jumper Settings for 10BASE-T and Non-10BASE-T Hubs

���������������������������������������� HP StarLAN 10,
�������������������������� SynOptics��� AT&T StarLAN 10,�
������������� 10BASE-T���� LattisNet��� DAVID Systems���� BULL Hub 10
������������� (default)� (non-10B-T)��� (non-10B-T)������ (non-10B-T
Link Beat������� ON����������� OFF������������ OFF������������ OFF
Equalization���� TX����������� RX������������� TX������������� RX
DC Signal������� OFF���������� ON������������� OFF������������ OFF
Xsmit Level����� NORM��������� LOW������������ NORM����������� LOW
Rcv Thres������� NORM��������� LOW������������ NORM����������� LOW-

3c523 Versions not Compatible with 486+
�� The "old" 3C523 have a copyright date of 1987 on them and will only work properly in a 286 or 386. From my expiriences, it will only let the first 8MB RAM be usable no matter how much RAM you have installed.� The newer revision will have a 1990 or 1991 date on it.�

From Peter
�� Fact is: some series of the older Ethernet/MC have a microcode incompatible with 486-processors. (Bus signalling most likely - haven't tested that in depth)�
�� Symptom: they worked fine as long as they were used in Mod. 70/80 - but when the customer swapped them to the new bought 76/77 they went belly up and did not even pass the DOS-based diags test.�
�� These are older ones produced before 1990 - but ironically not all old cards are automatically affected. There was a diagnostic program available from 3COM (I think it came with the revised E/MC) which checks the microcode level and warns for possible incompatibilities. In addition some of the setup / diags and driver software had a problem with later OS-versions (did not run properly under PC-DOS 4.x and above due to "version conflict"). Whatever.�

Component Differences, Old vs. New
>Is that a 3C523? ISTR that those (or most of them, anyway) wouldn't� work properly in anything� than a 386.�

The original 3C-523 has a limitiation - the later ones (3C-523B) hasn't. Roughly the two can be differed by looking on the board:�

Old Model
�� Round "transformer", many "through-hole" chips and "classical" resistors, long DIL "i" (Intel) 82586 MCU, "(C) 1987 3Com" at frontside�

New Model
� Square "3Com" transformer, mainly SMD chips with square QFP "i" Intel 82586 MCU, "(C) 1991 3Com" along the bottom/front.�

The old one will most likely not run with anything bigger than a 386DX - the new one hasn't got this problem. Works with 486 and Pentium. Both cards have the same card-ID and use the same ADF, so you cannot tell which is which by the ID only.�

Enable/Disable Adapter
�� Use the Disabled setting if you are not using the adapter and enabling it causes a conflict with another device.
���� <" Adapter Enabled >, Adapter Disabled�

I/O Address Range
�� I/O addresses used by EtherLink/MC. The addresses in this range cannot be used by another installed device
��� <"� 300 to� 307 ">, 1300 to 1307, 2300 to 2307, 3300 to 3307�

Interrupt Level
�� Interrupt level used by EtherLink/MC. This adapter's interrupt level can be shared with another device.� You may be able to improve performance
by selecting a level that is not used by any other device.
�� <" Channel 3 " ( INT 3)>, 7, 9, 12

Packet Buffer RAM Address Range
�� RAM and ROM addresses used by EtherLink/MC.� The addresses in this range cannot be used by any other installed device.� The range represents
16K bytes of RAM addresses followed by 8K bytes of ROM addresses
�� <" 0C0000 to 0C5FFF " >, 0D0000 to 0D5FFF , 0D8000 to 0DDFFF

Transceiver Type
�� Transceiver used by EtherLink/MC. If you have a thin Ethernet network and wish to connect to the adapter's round BNC connector or you have a twisted pair Ethernet network and wish to connect to the adapter's 8 pin
RJ45 connector (EtherLink/MC TP only), select On-Board.� If you have a drop cable from an external transceiver and wish to attach to the adapter's 15 pin AUI connector, select External.
�� <" On-Board (BNC or RJ45) ">, External (AUI)

�� NOTE:� If Group 3 tests are running while the computer is connected to an active network, intermittent packet exchange failures may occur before the tests are done.� These failures can be avoided by running Group 3 tests on an inactive network in which only the computer being tested and the echo server are connected.

1.� Make sure adapter is completely seated in slot.
2.� Inspect all cables and connections.
3.� If you are running the Group 2 tests, make sure adapter is securely connected to a loopback plug (coax version only) or to a properly cabled inactive network.
4.� If you are running the Group 3 tests, make sure adapter is securely connected to a properly cabled inactive network and that an echo server is set up on the network.
5.� Make sure that none of the adapter settings conflict with any other��� peripheral or software program (such as 3Com's Extended Memory Manager) installed in the computer.� For a list of system resources commonly used by other peripherals, select "Additional Adapter Information" from the main menu, then "System Resources" from the Information submenu.�
6.� Make sure that the transceiver type selected is correct.
7.� Running tests while connected to an active network can cause intermittent failures.� These failures can be avoided by using an inactive network on which only the computer being tested (and an echo server if running the Group 3 tests) is connected.
8.� If you installed an EtherLink/MC TP adapter, check the LEDs on the back-plate of the adapter.� The yellow (ACT) LED is on when there is data
�transmission activity on the adapter.� This light will go on during the Group 2 and Group 3 tests.� The green (LNK) LED will be on when there is a correct connection between the adapter and the hub.� If the link pulse jumper is in the OFF position, the green LED will be on whether or� not there is a connection.
9.� If you have installed an EtherLink/MC TP adapter, make sure that the�
��� settings for the following jumpers are correctly configured for the hub:
������� RECEIVE THRESHOLD
������� DC SIGNAL
������� LINK PULSE
������� EQUALIZATION
������� WIRE IMPEDANCE
������� TRANSMIT LEVEL
���� For information on setting these jumpers, select "Additional Adapter��� Information" from the main menu, then "Twisted-pair Options" from the���� Information submenu.
10. The computer slot may be defective.� Install adapter in� another slot and run tests again.
11. The computer in which the adapter is installed may be defective. Install the adapter in a known functioning computer and re-run the tests.
�12. The loopback plug� may be defective.� Try a different loopback plug.
13. Replace failed adapter with a known good EL/MC adapter with the same jumper settings.� If the second EL/MC adapter fails, something is wrong with the test environment, not with the adapter.