3com 3C527 EtherLink/MC 32

Note: This page is mostly best guesses. Inferences have been made from experience, snippets from sources, and SWAGs. As with anything Micro Channel, we lack documentation on all variants. This page is VERY incomplete.

@0041.ADF 3Com EtherLink/MC 32 Ethernet Adapter
@8EF5.ADF IBM High Performance Ethernet LAN Adapter (Can't Say)
   Note: My SWAG they "Can't Say" this was a re-badged 3C527 (therefor cheaper)

BINs for 2-1 (thx to Michal Necasek)

3C527X.EXE V3.3 Etherdisk for Etherlink MC/32
3C527N.EXE E-disk version 3.4, includes NT driver
WFW501.EXE 3C501 or 3C527 (self extracting)

3c527 Technical Reference
Device Driver Issues in High-Performance Networking (AIX 3.2.5)

3C527 Etherlink/MC32
2-1 [31F4075]
   3c527 EPROM and Cache
   Network Management ROM Format
FC 2980 Versions
ADF Sections

3C527 EtherLink/MC 32

1B CSROM.EVN 5613-33
2B CSROM.ODD 5613-34
2D 80C186-12
3E 74F41 [2-1]
3,4 D/C
4A,5A 8Kx8 CMOS SRAM [2-1]
5D 3Com 6399-01
6B 25.0000 MHz Osc
8A 74ALS245A [2-1]
8D 82586-10
10B LS125A [2-1]
11C 3Com 6400-03
13B PAL [2-1]
13D 3Com 6401-04
14D 3Com 6428-01
15C AMD 2244
16E MC10116P Triple Line Rcvr
J1 EPROM size
J3 Unknown 6-pin header
J4 Two pin header, unk
NE1 Neon Lamp
T1 Valor LT6018
Y 12MHz osc? [Early!]
Y3 20 MHz osc

1B / 2B 32K microcode, split over two AMD 27C128-125DC
4B/5B 8Kx8 CMOS Static RAM
7B 3Com's OUI and MAC address
8D Intel 82586 IEEE 802.3 Ethernet LAN Coprocessor
11E SEEQ PQ8023A Manchester Code Converter MCC
16E MC10116P Triple Line Receiver, odd, they used those little press-in pin sockets.

Additional Chips on the 2-1 that are not on 3c527
4A/5A CXK5864BM-10L (8,192-Word x 8-bit High Speed CMOS Static RAM)
8A 74ALS245A Octal transceiver (3-State)
10B LS125A Quad 3-state Buffer
13B 16L8-15C

3E on 81F7913 and 31F4075
74F41 Hex Inverter Schmitt Trigger
   Note: Not used on 00G3368

2-1 [31F4075] (thx to Michal Necasek)

3c527 EPROM and Cache

EPROM Lower Upper
3 - 2 - 1 3 - 2 - 1
27128 x - x - o x - x - o
27256 x - x - o o - x - x
27512 o - x - x o - x - x

After endlessly chanting "Chet Heath" for hours to clear my mind, I noticed the jumper positions to the left of the EPROMs. A bit odd, 3Com never changed the PCB, they just shunted it for a 27128 and called it a day. They could have changed the foil, shunted it internally.\, then drop the (unneeded) silk screening, save a few pennies per card.

The three choices are: 27128, 27256, 27512

Another brilliant blue flash, the 3c527 has TWO KM6264BL6-10, 8Kx8 bit Low Power CMOS Static RAM (I think). The 2-1 has FOUR 8Kx8. I see other artifacts, some SMD LEDs, another set of (empty) jumpers....

Michal Necasek Compares "2-1" to 3C257
   Your component 7B is labeled as 2EEF7D. Mine says 2E2FD5, with 02608C in much smaller print. I am pretty sure the 7B IC is the PROM holding the MAC address. 02608C is 3Com's OUI, and the rest is presumably the remaining 24 bits of the MAC address.

   For a moment I was pondering what the big PROM (32K total) was even for when it's clearly not a boot ROM, then realized that it has to be microcode for the on-board 80186. It certainly contains x86 code. Interesting adapter.

Network Management ROM Access
The 256 byte bipolar Network Management PROM contains the 48-bit network address value as well as other pertinent adapter information. Only the Micro Channel's host processor has access to read the PROM which is accomplished through the POS mechanism of
sub-addressing--a technique that entails writing 16-bit address values to POS registers 6 and 7. When the address values are non-zero, then the Network Management PROM data is visible to the host through the POS register bit 3.

IBM 2-1: Vital Product Data ROM containing the network address and revision information. 3Com 3c527: Network Management ROM, same fields but different field content.

Differences Between EtherLink/MC 32 and IBM 2-1

  1. The 2-1's I.D. number is 8EF5, and the 3c527's is 0041.
  2. The 2-1 supports exception condition handling such as parity checking/generation, and the 3c527 does not. (Ed. probably Selected Feedback as well...)
  3. The two products will have slightly different PCB fabs.
  4. 2-1  Vital Product Data ROM (network address and revision info).
    3c527 Network Management ROM uses the same fields but with different field content.

The network management ROM is a hybrid of the Csay ROM. IT is identical except the first ASCII field has "NMR" instead of "VPD" and two fields have been added, date (*DT) and a copyright (*CR). The fields have been filled with zeroes as place holders for IBM proprietary data.

The Network Management ROM Format is described HERE.

Uli Link on 2-1 Performance
Even on old and slow RS/6000 the 2-1 adapter gives a throughput close to the theoretical maximum of half-duplex 10MBit/s Ethernet with moderate CPU usage. So if the busmaster driver (for PC Operating systems) is written 16MByte RAM ISA busmaster safe the adapter does a fast busmastering into a low mem address buffer and then the CPU copies the data to the destination (a.k.a. double buffering) completely wasting all benefits of busmastering.

I once have tested the 2-1 with Novell Netware 3.12 and got very good results.

When the drivers was developed such Ethernet cards were connected to hubs and not switches. You don't need to fiddle around with fairness on the Ethernet bus on a switch port. The switch port should generate "collisions" to slow down the port if the destination cannot handle the bandwidth at the moment. Those days server adapters were optimized for combined throughput under heavy load on a shared media bus.

Programming Form

Rick Ekblaw:
   The interface is pretty simple, commands are mapped to bits and bit groups, there are some command and status registers starting at the I/O base, there are mailboxes and so on. It looks a bit like the Spock interface and a bit like the AHA-154x/164x interface which uses mailboxes.

Differences Between 3C527 and 2-1
"The IBM adapter supports exception condition handling such as parity checking/generation, and the EtherLink/MC 32 does not"

Drivers for 2-1

>The 3C527 and this card are the same thing with different card-IDs.

Now I know where I have seen it, I should have a 3C527. But then, the type 2-1 card could be assigned to 0041.ADF renamed to 8EF5.ADF, and the drivers, provided they do not check the adapter ID, work for the type 2-1 card (if not, the adapter ID can be patched in the driver object code). I saw some of the 8EF5 driver code, the POS bytes match the 0041.ADF quite exactly.

FC 2980 Versions

FRU 81F7913 has P/N 71F1157, 71F1182, 71F1183 - Early versions
   71F1182 has the yellow wire rework, a small osc to the right of the 80186, pads for J4 and 5, pins for a jumper under the lower left of the big 3com 6428-01 [14D], J3 populated, populated jumpers for the EPROM size.

Note that 71F1183 looses the small osc to the right of the 80186, no yellow wires.

P/N 71F1182

P/N 31F4073 CE P/N 31F4075 - Intermediate. Needs minimum 3.1.5

FRU 00G3368, P/N 00G3367 - This looks to be the last version

AdapterID 0041 3Com EtherLink/MC 32 Ethernet Adapter

Enable/Disable Adapter
   Use disabled if you are not using the adapter in your system
   <"Adapter Enabled">, Adapter Disabled

I/O Base Address
   The EtherLink/MC 32 occupies 16 bytes in the I/O Address space.
   < "728x" (7280-728f)>, 729x (7290-729f), 768x  (7680-768f), 769x (7690-769f), 7A8x (7a80-7a8f), 7A9x (7a90-7a9f), 7E8x (7e80-7e8f), 7E9x (7e90-7e9f)

Shared Memory Ranges
   A 16K memory window is required, located at any of eight possible address ranges.
     <"RANGE:D800-DBFF, 16K">, DC00-DFFF, 16K, C000-C3FF, 16K, C400-C7FF, 16K, C800-CBFF, 16K, CC00-CFFF, 16K, D000-D3FF, 16K, D400-D7FF, 16K

Interrupt Level
   Interrupts can be shared with another device, if the software drivers for both devices  support interrupt sharing.  You may be able to improve performance by selecting a level that is not used by another device.
     <"Level 10">, 11, 9, 12

Arbitration Level
   Level eight has the highest priority, and higher levels decrease priority
     <"Level 10">, 11, 12, 13, 14, 8, 9

Fairness Enable
   Fairness is provides equal access is to the host bus for competing bus masters and in most instances should be enabled.  In a system where it is desired that a higher priority device have increased bus utilization, fairness may be disabled.
     <"Enabled " >, Disabled

Address Burst Management
   This enables the Etherlink/MC 32 to relinquish control of the Micro Channel Bus at specific address boundary crossings.  As an example, if the 16-byte boundary Address Burst Management is selected, the Bus Master relinquishes bus control as the address increments from xx0Fh to xx10h. In some system configurations, the Address Burst Management feature may provide improved performance, but generally it should be disabled.
    <"Disabled">, 16-byte boundary, 32-byte boundary, 64-byte boundary

Transceiver Type
   The active connector is determined by the selection of the Transceiver Type. If you have a thin ethernet network and wish to connect using a T-connector, select On-board.  If you have the thick drop cable from an external transceiver and wish to attach to the 15-pin AUI cable, select External
    <"On-board Transceiver (BNC)>, External Transceiver (AUI)

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