cabbie@chinet.UUCP (Richard Andrews) (01/12/87)
A friend of mine called me last night with a problem that is interesting. He had just bought a SH204 hard disk drive and found that whenever he wrote to the hard disk he would munge the directory. He can read files ok and is using rev 8 software for the harddisk. I had him bring his console and drive over and found that with his console he indeed did munge the directory. With my console everything was OK though. We replaced the DMA chip, and the 1772 to no avail and have run out of ideas. His machine is a 1 meg 520 with piggybacked chips (both installed by me) and TOS is in ROM. My machine has the modulator and his doesn't, not that it makes any difference. Memory checks out ok on both machines so i have to assume that memory is ok. Could the ROM routines be bad due to a hardware problem (bad solder joint) or am I barking up the wrong tree? What else could it be? Both the MMU and GLUE are -20 revisions. BTW when he wipes out a directory and then you read it the whole system locks up with no mouse icon and then about 4 seconds later the screen turns to vertical stripes! Bizarre! Its kind of like filling screen memory with $01 from SID. After that the system re-boots. When the directory is munged in this fashion and you try to read it with a good console the same thing happens. I never thought that a directory could wipe out the system. That would make for a interesting copy- protection scheme. Read too much of the directory and BOOM! I have also seen the directory turn into all 'SSSSSS'. Real wierd disk usage amounts too. Something like "1 )9 (8530( * bytes free". Any ideas anyone? Allen? Neil? -- ******************************************************************************* Any opinions expressed above are my own. Rich Andrews They can be yours too. Please send $19.95 to.....ihnp4!chinet!cabbie *******************************************************************************
todd@zeke.UUCP (Todd Burkey) (01/12/87)
In article <1014@chinet.UUCP> cabbie@chinet.UUCP (Richard Andrews) writes: >ideas. His machine is a 1 meg 520 with piggybacked chips (both installed >by me) and TOS is in ROM. My machine has the modulator and his doesn't, You might want to look for noise on the RAM data/address lines. I had the same problem because too thin a wire was used on my 1Meg upgrade. A fairly thick wire is actually needed to reduce noise (reflections, etc). -Todd Burkey ..!mecc!zeke!todd -- -Todd Burkey ZYCAD Corporation ..!mecc!zeke!todd
jdg@elmgate.UUCP (Jeff Gortatowsky) (01/13/87)
A gentleman from Berkely(SP?) Microsystems (maker of DMA->SCSI boards)
told me that some(!) 520ST's power supplies can't keep the 5 volt line
at an adequate level for some(!) DMA chips, when the 520 also has 1meg
of RAM installed. This might be the problem.
--
Jeff Gortatowsky {allegra,seismo}!rochester!kodak!elmgate!jdg
Eastman Kodak Company
<Kodak won't be responsible for the above comments, only those below>