german@uxc.cso.uiuc.edu (08/19/87)
One possible cuprit would the the interrupt level of the ethernet card
conflicting with that of the COM port you are using. I am not positive
that the AT&T 6300's COM ports would use the same interrupt level, but
on the IBM PC & PC/ATs COM1 is IRQ 4 and COM2 is IRQ 3. You would probably
want to use IRQ 2 on the ethernet cards unless that conflicted with
some other piece of hardware in the machine. (3270 emulation cards for example)
I have not tried your exact configuration, but this is the type of problem
you run accross from time to time when dealing the PC networks.
Greg German (german@uxc.CSO.UIUC.EDU) (217-333-8293)
US Mail: Univ of Illinois, CSO, 1304 W Springfield Ave, Urbana, IL 61801
Office: 181 Digital Computer Lab.burton@parcvax.Xerox.COM (Philip M. Burton) (08/21/87)
In article <174200063@uxc.cso.uiuc.edu> german@uxc.cso.uiuc.edu writes: > > >One possible cuprit would the the interrupt level of the ethernet card >conflicting with that of the COM port you are using. I am not positive >that the AT&T 6300's COM ports would use the same interrupt level, but >on the IBM PC & PC/ATs COM1 is IRQ 4 and COM2 is IRQ 3. You would probably >want to use IRQ 2 on the ethernet cards unless that conflicted with >some other piece of hardware in the machine. (3270 emulation cards for example) >I have not tried your exact configuration, but this is the type of problem >you run accross from time to time when dealing the PC networks. Greg is absolutely right on. Xerox has software that connects PC's to our XNS networks, and we use cards supplied by 3COM. We have run into a number of compatibility problems that all come down to interrupt level conflicts. The very first "Etherlink" card can be set for IRQ 3 and 5 only, but the second (full length) and third (half length) allow any interrupt between 2 and 7. Just be sure that your DMA settings are both one. One other source of problems is the "DIX" setting (DEC-Intel-Xerox). If you are using "thin" Ethernet you must set the jumper differently than if you are using standard Ethernet with a 15 pin drop cable. Hope this helps. -- Philip Burton Xerox Corporation 408 737 4635 ... usual disclaimers apply ...
hobson@aramis.rutgers.edu (Kevin Hobson) (08/25/87)
In article <441@parcvax.Xerox.COM> burton@parcvax.Xerox.COM (Philip M. Burton) writes: > In article <174200063@uxc.cso.uiuc.edu> german@uxc.cso.uiuc.edu writes: > > > > > >One possible cuprit would the the interrupt level of the ethernet card > >conflicting with that of the COM port you are using. I am not positive > >that the AT&T 6300's COM ports would use the same interrupt level, but > >on the IBM PC & PC/ATs COM1 is IRQ 4 and COM2 is IRQ 3. You would probably > >want to use IRQ 2 on the ethernet cards unless that conflicted with > >some other piece of hardware in the machine. (3270 emulation cards for example) > >I have not tried your exact configuration, but this is the type of problem > >you run accross from time to time when dealing the PC networks. > > > Greg is absolutely right on. Xerox has software that connects PC's to our > XNS networks, and we use cards supplied by 3COM. We have run into a number > of compatibility problems that all come down to interrupt level conflicts. > > The very first "Etherlink" card can be set for IRQ 3 and 5 only, but the > second (full length) and third (half length) allow any interrupt between > 2 and 7. Just be sure that your DMA settings are both one. > > One other source of problems is the "DIX" setting (DEC-Intel-Xerox). If you > are using "thin" Ethernet you must set the jumper differently than if you > are using standard Ethernet with a 15 pin drop cable. > The problem is that 3com etherseries cards interrupt levels conflict with Ibm-pcs, XTs, ATs, and compatibles slot devices (hard disk, floppies, parallel ports, com ports, etc). Depending on the the machine, interrupt levels vary for each device. The default configuration for the card is for interrupt level of 3 (also the interrupt for com2). The new 3c501 (half-cards) can be changed from 2-7 interrupts. From the MIT tcp/ip manual (minus the scribe formatting commands): ------------------------------------------------------------------ This section describes the installation procedures for network interface hardware supported by PC/IP, and also notes a problem found with some old memory cards. Before you install your network interface, you need to select a DMA channel (note that the proNET card can use two separate DMA channels, one for transmitting packets and one for receiving them) for it and an interrupt vector. The board may need to be reconfigured to use your selections, and you also have to inform the software via the PC/@b[custom] command. It is important that the DMA channel and interrupt vector you select are not being used by any other hardware in the machine. Below is a chart showing what channels and vectors the network interfaces supported by PC/IP can use, and what channels and vectors are already in use in a PC, PC/XT and PC/AT. Network Interfaces Interrupts Dma Channels proNET 2, 3, or 4 1, 2, or 3 3COM Etherlink (old revs) 3 or 5 1 or 3 3COM Etherlink (newer) 2, 3, 4, 5, 6, or 7 1, 2, or 3 Interlan NI5010 3 or 5 1 or 3 PC Devices COM1 (same for AT) 4 none COM2 (same for AT) 3 none Printer 1 (same for AT) 7 none Printer 2 (same for AT) 5 none Floppy disk 6 3 PC/XT hard disk 5 2 AT Devices Floppy and hard disk 6 2 If you cannot, or choose not to, use a DMA channel, you should set the DMA channel (via PC/@b[custom]) to 0. The driver will then use a tight loop to transfer data from the card. We recommend using DMA, however. If you install more than one network interface in your machine, or have some other unusual hardware, it is also important to make sure that the base I/O address of the interface does not conflict with any other hardware. Refer to the documentation for the appropriate interface for details on setting the base I/O address. ..... There are several jumper-selectable hardware options on the 3COM Etherlink Ethernet card. The cards come in two forms. The first, older form, is identifiable by the label "Rev. A" or "Rev. x.y" where x and y are integers; the card is usually green in color. The second, newer form, is identifiable by its blue color and by the presence of a humongous, 64-pin chip in the upper left corner of the card (when held with the chips visible and the bus connector pointing down.) The two kinds of cards have completely different labels for their option setting jumpers, and the newer cards have a few additional settings. The option set shown below is known to work with the PC/IP Ethernet packages. The choice of which DMA channel and which interrupt vector to use depends on what other I/O equipment is attached to the PC. For example, on an IBM PC/XT the hard disk, floppy disk, and printer are configured to use interrupt vector positions five, six, and seven, leaving two, three, and four for other attached devices. The Ethernet commonly uses interrupt vector position three. 3COM Etherlink card option settings: Rev. B Rev. A label label suggested jumper position DMA REQ jp1 channel 1 (must match software) DMA ACK jp2 Must match DMA REQ or jp1 Interrupt jp3 vector 3 (must match software) I/O address bit 9 n/a right (1) I/O address bit 8 jp4 right (1) I/O address bit 7 jp5 left (0) I/O address bit 6 jp6 left (0) I/O address bit 5 jp7 left (0) I/O address bit 4 jp8 left (0) Memory address bit 19 n/a right (1) Memory address bit 18 jp9 right (1) Memory address bit 17 jp10 right (1) Memory address bit 16 n/a left (0) Memory address bit 15 n/a right (1) Memory address bit 14 jp11 right (1) Memory address bit 13 jp12 left (0) Memory address bit 12 jp13 left (0) Memory enable jp14 right (disable) n/a sw1 Left for onboard transceiver, right for external transceiver U11/U10 n/a Plug goes in socket U10 for onboard, socket U11 for external transceiver Older Etherlink cards can be set only to interrupt vector positions three and five, and therefore must use position three in an XT. Similarly, the PC/XT uses DMA channel three for the hard disk and DMA channel two for its floppy disk, so the Ethernet must use DMA channel one. In recent shipments the 3COM Ethernet card has been configured at the factory with exactly these two settings. Certain combinations of 3COM Etherlink cards that are labeled "Revision B" with external transceivers generate improper Ethernet waveforms. These improper waveforms can be decoded without trouble by any 3COM interface, but some Ethernet interfaces from other manufacturers cannot decode these improper signals. This problem may be the cause when a PC can communicate with some, but not other, hosts on the same Ethernet. If switching the 3COM Etherlink card to use the internal transceiver clears up the difficulty, then the transceiver incompatibility problem is almost certainly the cause. Contact a 3COM sales representative for information on an engineering change that corrects the problem. Some IBM 64K/256K memory expansion cards have a design flaw that causes trouble when an I/O device uses DMA channel 1. (The PC/IP software usually uses DMA channel 1 for the Ethernet or the Pronet.) The symptom of this design flaw when running PC/IP software is a catastrophic crash with the screen displaying the message @c"PARITY CHECK 2". The crash usually occurs within the first hundred or so packets transmitted to or from the network. If this problem appears, one should check the memory expansion card to see whether or not it has this design flaw, and whether or not it has been field-upgraded. Flawed cards have a connection between pins nine and ten of chip U49. (The connection is a very small printed circuit stripe on the underside of the card.) Repaired cards have had that connection severed, and two new wires added, from chip U33 pin eight to chip U33 pin eleven, and from chip U33 pin ten to chip U49 pin nine. Note that making changes such as these must be done with care to avoid damaging the card, and may void any warranties. If you have a flawed card it may be appropriate to inquire of your dealer what action should be taken. Alternatively, the network can be operated using DMA channel 3 if that channel is not already in use for some other device such as a hard disk, or can operate without DMA by selecting channel 0. 23 January 1986. This document is in file hard-inst.mss -- - Kevin Hobson - ARPA: hobson@rutgers.edu - UUCP: {ames, seismo, harvard, ucla-cs, cbosgd, moss}!rutgers.edu!hobson - BITNET: hobson@cancer.bitnet - Rutgers University, New Brunswick, NJ 08903 (201) 932-2260 (201) 932-5027