brians@eecs.cs.pdx.edu (Brian Smith) (04/06/91)
The manual for Interactive Unix states that it is possible for some DMA chips to malfunction when more than one allocated DMA channel is used simultaneously. Is there any way to tell whether a motherboard has this defect? One of the boards in my system which uses DMA is the SCSI disk controller, so I'd rather not test this under Unix and risk losing my filesystem. Even a DOS program to test for this problem would be fine. My motherboard is the AMI Voyager 486-25. Thanks, Brian Inet: brians@cs.pdx.edu UUCP: tektronix!pdxgate!brians -------------------------------------------------------------------------------- Nine megs for the secretaries fair, | One disk to rule them all, | Seven megs for the hackers scarce, | One disk to bind them, | Five megs for the grads in smoky lairs, | One disk to hold the files | Three megs for system source; | And in the darkness grind 'em. | --------------------------------------------------------------------------------
cpcahil@virtech.uucp (Conor P. Cahill) (04/07/91)
brians@eecs.cs.pdx.edu (Brian Smith) writes: >The manual for Interactive Unix states that it is possible for some DMA chips >to malfunction when more than one allocated DMA channel is used simultaneously. >Is there any way to tell whether a motherboard has this defect? One of the >boards in my system which uses DMA is the SCSI disk controller, so I'd rather >not test this under Unix and risk losing my filesystem. Even a DOS program >to test for this problem would be fine. You have two questions. 1. can my motherboard do simultaneous DMAs 2. can my motherboard do bus mastering DMA (the scsi card) The Fastback backup software for dos, as part of it's installation, tests the abilities of the DMA controller with respect to question 1. I don't know of any tests for question 2 other than install and see how it works. (Be sure to have a backup before you start). >My motherboard is the AMI Voyager 486-25. My AMI 386/33 dies when bus-mastering DMA is attempted. -- Conor P. Cahill (703)430-9247 Virtual Technologies, Inc. uunet!virtech!cpcahil 46030 Manekin Plaza, Suite 160 Sterling, VA 22170
usenet@carssdf.UUCP (John Watson) (04/09/91)
In article <2247@pdxgate.UUCP>, brians@eecs.cs.pdx.edu (Brian Smith) writes: > The manual for Interactive Unix states that it is possible for some DMA chips > to malfunction when more than one allocated DMA channel is used simultaneously. > My motherboard is the AMI Voyager 486-25. > Check your DMA Chip. If it is an 82C206 multifunction peripherial controller, try a different vendor if you have that problem. I have had good success with the Chips & Technology Branded version. I had spooky intermittent problems with a "second source" version (I tried 3 from that mfgr). The C&T chip worked the first time, using 486-25,AMI Bios, Tiwan Board. John Watson
tmh@prosun.first.gmd.de (Thomas Hoberg) (04/11/91)
In article <2247@pdxgate.UUCP>, brians@eecs.cs.pdx.edu (Brian Smith) writes: |> The manual for Interactive Unix states that it is possible for some DMA chips |> to malfunction when more than one allocated DMA channel is used simultaneously. |> Is there any way to tell whether a motherboard has this defect? One of the |> boards in my system which uses DMA is the SCSI disk controller, so I'd rather |> not test this under Unix and risk losing my filesystem. Even a DOS program |> to test for this problem would be fine. |> This should really only concern usage of the motherboards DMA chips (Intel 8237). Since these are really left overs from 8-bit days and run at 4MHz by default, they are quite combersome to use and slow. Some boards like those with a C&T chipset will allow them to clock at 8MHz, though. In any case *NO* SCSI host adapter that I am aware of will use these on board DMA a chip, but revert to bus mastering DMA, if they use DMA at all. Bus mastering means, they pull a DREQ line on the I/O bus to force the CPU off the bus and then generate memory cycles themselves. The Adaptec 154x works that way for example. The only devices actually using the 8237s that I know of, are the floppy disk and some QIC-02 cartrige tape controllers like those from Archive (maybe some network cards, too?). I don't know what happens if you try to use to floppys at the same time, since I guess they have to share DMA channel 2 (probably just doesn't work, after all the PC was a DOS machine). Whether you can use a QIC-02 tape streamer and a floppy at the same time depends on a tunable parameter called DMAEXCL or something like that, I *think*. In any case your file system shouldn't be trashed by your playing around with two DMA channels at the same time. |> My motherboard is the AMI Voyager 486-25. |> |> Thanks, |> Brian |> |> Inet: brians@cs.pdx.edu |> UUCP: tektronix!pdxgate!brians |> -- tom ---- Thomas M. Hoberg | UUCP: tmh@bigfoot.first.gmd.de or tmh%gmdtub@tub.UUCP c/o GMD Berlin | ...!unido!tub!gmdtub!tmh (Europe) or D-1000 Berlin 12 | ...!unido!tub!tmh Hardenbergplatz 2 | ...!pyramid!tub!tmh (World) Germany | BITNET: tmh%DB0TUI6.BITNET@DB0TUI11 or +49-30-254 99 160 | tmh@tub.BITNET
det@hawkmoon.MN.ORG (Derek E. Terveer) (04/12/91)
cpcahil@virtech.uucp (Conor P. Cahill) writes: > 1. can my motherboard do simultaneous DMAs > 2. can my motherboard do bus mastering DMA (the scsi card) >The Fastback backup software for dos, as part of it's installation, tests >the abilities of the DMA controller with respect to question 1. I don't >know of any tests for question 2 other than install and see how it >works. (Be sure to have a backup before you start). The adaptec AHA154[02][ab] card has a bus mastering test built into it, so one can test the motherboard for bus mastering DMA *before* actually running an application that requires it (and potentially circumventing the misery involved in finding out after "some time" of running Unix). -- Derek "Tigger" Terveer det@hawkmoon.MN.ORG -- U of MN Women's Lax I am the way and the truth and the light, I know all the answers; don't need your advice. -- "I am the way and the truth and the light" -- The Legendary Pink Dots