karl@naitc.naitc.com (Karl Denninger) (11/03/90)
In article <1990Nov02.021739.9280@ddsw1.MCS.COM> nvk@ddsw1.MCS.COM (Norman Kohn) writes: >There have been many comments about boards that won't support >the Adaptec 1542[AB] SCSI bus master controller. >The board has a BIOS test routine, but I can say from experience >that it's possible for a motherboard to pass this test and >still generate errors running unix. Timing and/or DMA problems >on the motherboards have usually been blamed. Actually, it's usually the case that the motherboard fails to deassert IOCHRDY (I think that's the name of the signal) which is supposed to cause the adapter to immediately relinquish the bus. >I spoke with another board vendor last night and got another interesting >comment. He claims that the problem lies in the 1542B, which >allegedly sits on the bus too long during boot-up. >He says that a bus master is responsible for releasing the bus in >time for memory refresh, and that Adaptec's failure to release >the bus in time causes memory loss with predictably random (but poor) >results. A fix may be ready RSN. I have not discussed this yet >with Adaptec. Not true. The motherboard is responsible for telling the adapter when to shut the heck up and get off the bus if it has to do so. That's what IOCHRDY is all about. The 1542x boards all get off immediately when this signal so indicates. Every board I've seen so far that had trouble with the 1542B didn't bother indicating that it was time for refresh.... how is an adapter supposed to divine what the timing requirements are for this? Get out a scope and look at the appropriate pins on the bus. You'll see what I've seen many times before. Part of the problem is that bus mastering isn't often used, and thus isn't often tested by motherboard makers. It IS getting more common for companies to "care" about this these days... :-) -- Karl Denninger AC Nielsen kdenning@ksun.naitc.com (708) 317-3285 Disclaimer: Contents represent opinions of the author; I do not speak for AC Nielsen on Usenet.
ires@kaspar.UUCP (Bruce R. Larson) (11/05/90)
In article <1990Nov02.021739.9280@ddsw1.MCS.COM>, nvk@ddsw1.MCS.COM (Norman Kohn) writes: > There have been many comments about boards that won't support > the Adaptec 1542[AB] SCSI bus master controller. > ... > Timing and/or DMA problems on the motherboards have usually been blamed. > > [ lots deleted ] > > I spoke with another board vendor last night and got another interesting > comment. He claims that the problem lies in the 1542B, which > allegedly sits on the bus too long during boot-up. > ... I've just had an experience that suggests the 1542B is at fault. SUMMARY Erratic behavior with a 1542B, went away after installing a 1542A. THE PROBLEM I just sold a 386/33 cached Computer (by Caliber) to a client, but they witnessed erratic behavior after installing a 1542B and a Wren VI HH with ISC 2.2 pre-loaded. For the record, the 1542B passed the busmatering test with flying colors (g=dc00:9). Here are some of the odd things I witnessed. i) With all of the boards removed except the 1542B and a monochrone video adapter, the monitor frequently refused to display anything until the reset button was pressed a number of times. ii) whether the monitor would work at all was influenced by the relative positions of the video card and the host adapter. In most config- urations it just did not work. iii) The system would not even go through its memory test when the serial/parallel card was present. (No, there weren't any IRQ or base i/o address conflicts.) These sound like timing problems to me. THE SOLUTION I remembered a posting in this group (thanks again guys) about possible problem when using the 1542B. I replaced the 1542B with a 1542A and every problem vanished. I discovered this last night, so I haven't had a chance yet to fax the info to either Adaptec or my Adaptec supplier. > > -- > Norman Kohn | ...ddsw1!nvk > Chicago, Il. | days/ans svc: (312) 650-6840 > | eves: (312) 373-0564 Bruce R. Larson Integral Resources, Milton MA Internet: ires.com!blarson@cs.umb.edu Uucp: ..!cs.umb.edu!ires.com!blarson ========================================
nvk@ddsw1.MCS.COM (Norman Kohn) (11/06/90)
In article <9@kaspar.UUCP> ires@kaspar.UUCP (Bruce R. Larson) writes: >In article <1990Nov02.021739.9280@ddsw1.MCS.COM>, nvk@ddsw1.MCS.COM (Norman Kohn) writes: >> There have been many comments about boards that won't support >> the Adaptec 1542[AB] SCSI bus master controller. >i) With all of the boards removed except the 1542B and a monochrone > video adapter, the monitor frequently refused to display anything > until the reset button was pressed a number of times. >ii) whether the monitor would work at all was influenced by the relative > positions of the video card and the host adapter. In most config- > urations it just did not work. >iii) The system would not even go through its memory test when the > serial/parallel card was present. (No, there weren't any IRQ > or base i/o address conflicts.) > >These sound like timing problems to me. > >THE SOLUTION >I remembered a posting in this group (thanks again guys) about >possible problem when using the 1542B. I replaced the 1542B with >a 1542A and every problem vanished. I discovered this last night, I spoke with the technical person at the vendor who'd told me this. He says that it's a characteristic of boards using the C&T chipset. The 1542B holds the bus too long during its ROM boot-up. Later buson/busoff are configurable in software (e.g., under ISC unix). This is allegedly a matter of optimistic timing programmed into the on-board ROM and could be solved with a ROM upgrade (fix). Karl Deninger may be right that the motherboard could/should speak up for itself. I called Adaptec but have not heard back from their technical people yet. -- Norman Kohn | ...ddsw1!nvk Chicago, Il. | days/ans svc: (312) 650-6840 | eves: (312) 373-0564