rferguso@gn.ecn.purdue.edu (Robert S. Ferguson) (03/28/91)
I have noticed that my 1571 writes more slowly on side 2 of a disk. After each sector is written, I can hear the head move, then move back into place. The disks were formated with that same drive, and it seems to occur only when writing to side 2 of a disk. What I want to know is, is this a problem with all 1571's, or just older ones? or is it just mine? Can it be fixed? <boB< -- Where's the KA-BOOM? | Robert Ferguson There was supposed to be an enormous, | rferguso@ecn.purdue.edu (or) Earth-shattering KA-BOOM! -- Marvin Martian | rferguso@gn.ecn.purdue.edu r-znvy-zr-vs-lbh-pna-ernq-guvf-naq-lbh-ner-n-grrantr-zhgnag-avawn-ghegyrf-sna
cs4344af@evax.arl.utexas.edu (Fuzzy Fox) (03/28/91)
In article <1991Mar28.024743.16062@gn.ecn.purdue.edu> rferguso@gn.ecn.purdue.edu (Robert S. Ferguson) writes: >I have noticed that my 1571 writes more slowly on side 2 of a disk. >After each sector is written, I can hear the head move, then move back into >place. The disks were formated with that same drive, and it seems to occur >only when writing to side 2 of a disk. What I want to know is, is this a >problem with all 1571's, or just older ones? or is it just mine? Can it >be fixed? This is a stupid bug in the original 1571 ROMs. What's happening is that every time a file allocates a new sector, the BAM block on side 1 of the disk is being read in, updated, and written out again. This is horribly slow. The drive is supposed to simply keep a copy in RAM and update after the file is closed, but it does not. The solution is to upgrade your ROM. You can get the upgrade from Commodore (I think, no details here), or if you buy a replacement ROM such as JiffyDOS, it will have the latest upgrades in place. The upgrade will also fix (finally!) the save-replace bug. -- David DeSimone, aka "Fuzzy Fox" on some networks. /!/! INET: an207@cleveland.freenet.edu / .. Q-Link: Fuzzy Fox / --* Quote: "Foxes are people too! And vice versa." / ---
rferguso@gn.ecn.purdue.edu (Robert S. Ferguson) (03/28/91)
OK, so now I know the problem is due to old ROMs in my drive. How do I go about replacing it? Does anybody have the part no., price, address of where I can get a new one? I don't have the $$$ for JiffyDos, at least not yet. :-( <boB< -- Where's the KA-BOOM? | Robert Ferguson There was supposed to be an enormous, | rferguso@ecn.purdue.edu (or) Earth-shattering KA-BOOM! -- Marvin Martian | rferguso@gn.ecn.purdue.edu r-znvy-zr-vs-lbh-pna-ernq-guvf-naq-lbh-ner-n-grrantr-zhgnag-avawn-ghegyrf-sna
andy@ccwf.cc.utexas.edu (Andrew Hackard) (03/30/91)
If I remember correctly, the problem is that many of the tracks on side 2 are allocated by the BAM on side 1; when the 1571 writes a sector on side 2, it has to go back to side 1 to mark the block as used. I don't know why that would make things so much slower, and I may be misremembering, so someone who is a bit more familiar with the hardware probably can give you a more detailed answer. --Andrew
cs4344af@evax.arl.utexas.edu (Fuzzy Fox) (03/30/91)
In article <46392@ut-emx.uucp> andy@ccwf.cc.utexas.edu (Andrew Hackard) writes: >If I remember correctly, the problem is that many of the tracks on side 2 are >allocated by the BAM on side 1; when the 1571 writes a sector on side 2, it has >to go back to side 1 to mark the block as used. I don't know why that would >make things so much slower... You've got it right. The problem is that there is only room in the 1571 RAM to stores one of the two BAM blocks. Also, some of the info is stored in BAM block 1 (side 1), and some in block 2 (side 2). The fact that they are on the same track, but different sides, helps a bit, but the main problem is that the head must seek to track 18 over and over, which really slows things down. The newer ROMs simply cache the BAM changes in RAM (as is normally done when side 1 is being allocated), so the seek to track 18 is not needed until the file is closed. -- David DeSimone, aka "Fuzzy Fox" on some networks. /!/! INET: an207@cleveland.freenet.edu / .. Q-Link: Fuzzy Fox / --* Quote: "Foxes are people too! And vice versa." / ---