dsmall@well.UUCP (David Small) (12/17/89)
Archive-name: blitz/announce Original-posting-by: dsmall@well.UUCP (David Small) Original-subject: Re: Blitz copy cable and utility Archive-site: xanth.cs.odu.edu [128.82.8.1] Reposted-by: emv@math.lsa.umich.edu (Edward Vielmetti) The basenote contains info about the BLITZ disk copier cable. This is essentially an analog copier. The "read-data" wire coming from drive "A" is connected directly to the "write-data" wire coming from drive B -- hence, whatever magnetic flux shows up on the track gets plopped onto the destination drive. This makes for a powerful copier indeed. I used to *sell* a copier extremely like this, called the L.E. Systems FDC system, back in '82 or so, for the Atari 8-bit. With 8 drives (1 master, 7 slaves) it would produce 7 exact copies of a very copy protected disk in around 17 seconds. I will attest that thousands of 8-bit disks from Synapse, Broderbund, Origin Systems, Paradise Software, Epyx, and others I can't recall 7 years later were produced on this system, and were very reliable. It finally went away during the big slump of the 8 bits. Now, I'm supposed to be anti-pirate, right? Why do I like this system? Bit-shift. See, when you write disks, if I've had it explained to me correctly, you're writing a bunch of small bar magnets on the disk. If the bits are north south south north, those two bits repel each other, and physically move away. Similarly, north south north south attract, and move closer. This makes them move away from the "window" that the data seperator uses to determine if a bit is there or not. As I understand it, "write precompensation" is the science of moving repelling bits closer together at write-time so they end up, after repelling, where they should be, and more or less the same for attracting bits. Now, when you analog copy, the bits start drifting, since there is no write precomp. My personal experience with both single and double density disks (heh! and even Commodore 64) is that you have no problems on first generation clones. Second generation, the innermost tracks, where things are the hairiest, start to glitch, and third generation is hopeless. Hence, this is a backup device that works best when you put a master disk in the "from" drive. It doesn't work at all well when copying a copy, in my experience. That tends to step on the copy-of-copy-of-copy piracy. (Sure, it doesn't affect BBS's, but that's another issue). The other nice thing about BLITZ is its simplicity. I have looked over the docs and it looks like 20 minutes with a soldering iron, nothing hard. Parts are a DB-25 connector from Radio Shack and a disk cable from your local Atari dealer (or Best Electronics). There does not seem to be a copyright on the supplied software. Thus, your major cost is the download. Even ST-World is offering the documentation on its monthly shareware disk. BLITZ copied, with no problems, literally every copy protected disk I own. I know people who use it for a formatter! (I don't recommend that, as it's a second-generation copy w/o verify). It is extremely fast. Technically, the big problem is syncing up index pulses. On both drives, they have to occur at the same time. If you just copy, you'll likely have a sector end up straddling the index pulse, and the 1772 automatically generates a CRC error if it sees an IP in the sector (bug in the chip, WD says). Thus the BLITZ has to get the drives spinning together, which is a matter of toggling the MOTORON line on and off at high speed to slow one drive until they sync. Doubtlessly the DB-25 printer port is used to supply both the index inputs and output motoron, drive select, step, and so on. It is also probably helpful if drive B runs slightly more slowly than A:, so A:'s track "finishes" at index pulse before drive B, just a little. That was the case for the L.E. copier. I understand an outfit in Las Vegas is already advertising and selling BLITZ cables and software, pre-made, ready to run. I know several people in Denver who have built them and they work, plus those on GEnie. Now, if we could just make pirate BBS copies of programs degenerate each time they're copied ... <wistful sigh>. I hope this information about BLITZ is of interest. -- thanks, Dave / Gadgets