XBR3D815@DDATHD21.BITNET (WERNER BRAUN, FB08 KERNCHEMIE) (12/21/87)
[ line to be eaten... ] I have run into some problems as i tried to copy files to a Harddisk. I had 2 SH205-Harddisks connected to my Mega ST4 and tried to copy a (german) TeX-Distribution from one Harddisk to the other. The fonts are located in a couple of subdirectories all named 'PXLnnnn', where 'nnnn' stands for a four digit number. I tried to copy the directories by opening two windows, selecting 4 directories and pulling them in the other window. For the first 2 or 3 directories all works well, but then suddenly the name of one of the directories will change! The 'X' of 'PXLnnnn' will turn in the Sqare-Root- Symbol or in a superscript '3'. I had *no* accessories installed, there was no folder-limit (4 meg is enough to run FOLDER999.PRG to get 999 extra folder slots...). The second controller was switched to unit 1, so there were no hardware interferences. If i copy the whole thing from floppies to harddisk, this problem never occurs. I remember hearing something about a bug in TOS relating to this problem a long time ago. Can anyone give me some further help or a workaround ? Werner Bitnet: XBR3D815%DDATHD21 Arpanet: XBR3D815%DDATHD21.BITNET@CUNYVM.CUNY.EDU
landon@apple.UUCP (Landon Dyer) (12/24/87)
> I have run into some problems as i tried to copy files to a Harddisk. > I had 2 SH205-Harddisks connected to my Mega ST4 and tried to copy a (german) > TeX-Distribution from one Harddisk to the other. The fonts are located in a > couple of subdirectories all named 'PXLnnnn', where 'nnnn' stands for a four > digit number. I tried to copy the directories by opening two windows, > selecting 4 directories and pulling them in the other window. For the first > 2 or 3 directories all works well, but then suddenly the name of one of the > directories will change! The 'X' of 'PXLnnnn' will turn in the Sqare-Root- > Symbol or in a superscript '3'. Single-bit errors on DMA transfer. If you have SH205 cables longer than eighteen inches they will not work reliably. If you have home-brew unshielded cables, or you have defeated the shielding (with a Y-cable), the same applies. [If your cables are longer than 18" and they came in the box with the SH205, let atari!neil know about it! And get them replaced.] SCSI data transfers (at least on the ST) are not checksummed or otherwise validated. The DMA bus doesn't have much fail-safe, and you can run for a long time before noticing sporadic single-bit errors. A simple test you can try is to read the same set of blocks over and over again (with Rwabs()) and compare consecutive reads; let it run overnight and see if you get any errors. It's sad that the ST's only high-speed port is fraught with so much flakiness and folklore about its use. If there's a single piece of hardware Atari should improve on the ST, it's the reliability of the DMA bus. [Sorry, John.] -Landon -- I speak for me.