Ray Arachelian wrote: Oops, I just realized that I made this very unclear! "They sure did" refers to unimplemented opcode use, which worked just fine on the C128. This wasn't meant to say that the C128 had problems with unimplemented opcodes. Or rather, we should say undocumented opcodes as they were clearly implemented. If you look closely at the 6502 opcode chart patterns there are some missing ones, these are actually there, but they were buggy in early 6500 series CPU's, so they were purposefully not documented. Certain folks saw the patterns and recognized that there should have been opcodes there and tried them, they worked. So they used them to prevent reverse engineering. :-)

Jules Richardson wrote: I distinctly remember that there was a book on how to program the 1541 in order to do exactly this, and had lots of examples. I unfortunately never owned it. I found it, at the time, in of all places, the Queens Public Library. I tried to re-check it out several times, but the Library wouldn't let me hold it any longer than about 2 cycles. :-) It had lots of code examples and such as to how to call the various track and sector format routines, so you could seek to a specific track (or half track) and then write the wrong track ID, or the wrong sector for example. I believe it was written by one of the guys that made one of the fancy copiers. Perhaps qcopy (not sure of the name) or the Basement Boys... wish I could remember the name of the book. :-( There's some stuff here: " http://rittwage.com/c64pp/dp.php?pg=protection " and " http://www.tkk.fi/Misc/cbm/docs/ " about these topics. There's also some interesting stuff here: " http://www.geocities.com/profdredd/cprogram/cprogram.html " I remember playing with the code in this book and forcing the 1541 to seek past track #45. When you did this, the 1541 would emit a loud clunk and then your drive head would be stuck. You'd have to take the 1541 apart and move the head manually. It might have been that same book or another, but it had info as to how to tweak the motor speed of the 1541 with a fluorescent light. The motor had lines on it which would appear to be stopped under the light of a fluorescent source at either 50 or 60Hz. (There were two rings of lines, one for US, and one for Europe.) There was also a pot on the 1541 board that you could tweak to control the motor speed. Another thing I ran into with the 1541 was that a (diode) bridge commonly blew out. The symptom of this was that the power LED would flicker at 30Hz when this happened. I couldn't find the right bridge at my local Rat Shack at the time, so after figuring out which of the 4 diodes in the bridge died, I found a large diode and soldered it to the pins of the bridge.) That bridge was a single component, not 4 diodes, but it was an easy repair. The diode wasn't quite right, so it didn't last very long, but it was a very easy repair, so I just repeated it. :-) A few other tricks at the time, it was possible to get stereo sound out of both the C128 and the C64 by taking another SID chip (these were expensive at the time ~$30-$50), and bend a couple of the pins. One was an address pin, the other was the sound out pin. You could then place the new SID chip right smack ontop of the existing one (piggy-back), solder a wire to the sound out pin and you got stereo. Another trick was if you had a tape drive, you could use it as a very crappy 1 bit audio digitizer. This didn't work all that well, but it was something. Later someone wrote an article (in RUN Magazine perhaps?) about getting a serial A->D converter. Was a little 8 pin chip that you could attach to the CIA's shift register to read the values off. Another trick was that if you had the Pet Emulator (which wasn't a real emulator, it just reshuffled video memory around to match the 4032's memory map for video), and attached a small speaker to one of the pins of the CIA which was the shift register output (I think this might have been like CB1 or CB2 or something like that), you could also get Pet like sound, but you'd have the change the poke addresses around to match the CIA's. Was useful for all those old Pet games. :-)

Zane H. Healy wrote: It was a small 8.5"x5.5" spiral bound book. I think it's probably this one, but not sure: http://members.aol.com/c64dir/kjtr/index.htm (Or something very similar to it.)

Ray Arachelian wrote: And here's the text of said book: <http://root.org/~nate/c64/KrackerJax/index.htm> Well, all of it up to page 161, at least... -- Phil. | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder philpem at dsl.pipex.com | Cheetah: Athlon64 3200+ A8VDeluxeV2 512M+100G http://www.philpem.me.uk/ | Tiger: Toshiba SatPro4600 Celeron700 256M+40G

After a very, very long time I have one of my C64's up and running (after a lot of cleaning tonight I was actually able to find a good place to get to it). However, I was only able to get one of the two 1541's up and running, it seems that one of my Serial cables is bad :^( What are the odds of one of the cables going bad while in storage, while the hardware itself seems OK. Didn't have a Joystick with the box of cables and stuff, but did have a pair of paddles, and just finished playing a few games of Omega Race :^) Now if I could just find that Lunix floppy! Zane -- | Zane H. Healy | UNIX Systems Administrator | | healyzh at aracnet.com (primary) | OpenVMS Enthusiast | | MONK::HEALYZH (DECnet) | Classic Computer Collector | +----------------------------------+----------------------------+ | Empire of the Petal Throne and Traveller Role Playing, | | PDP-10 Emulation and Zane's Computer Museum. | | http://www.aracnet.com/~healyzh/ |

On Sunday 03 September 2006 09:19 am, Ray Arachelian wrote: I remember a lot of "repairs" that involved me doing exactly that, often after the owner had been running some copy program... Speed wasn't often a problem with those drives, excepting those few cases I ran across where the tachometer winding in the motor opened up and they tried to run at darn near twice the normal speed. More of a problem was bad belts, they'd slip. I've never seen one do that. I have seen them where you'd turn the unit on and get no lights but the motor was running (bad 5V bridge) or you'd get normal lights but no motor activity at all (bad 12V bridge). That's exactly where I'd get the replacements I used, which were 4A parts instead of the idiotic 1A parts that were in there in the first place. In fact, I purchased a bunch of them back when and still have some, left over, NOS, if anybody needs one. :-) That's one way to do it, I suppose. The only advantage I see to bridges as opposed to separate diodes is convenience in manufacturing. I've heard of that one before, but have never seen it done. I have some of those old magazines around here someplace, maybe I oughta dig them out and see what I have and what's in them. Mostly software stuff, rather than hardware, as I recall. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Chuck Guzis wrote: I'm not sure you'd be able to swap it out - isn't the head preamp on the 1541 motherboard, not a separate drive interface board? -- Phil. | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder philpem at dsl.pipex.com | Cheetah: Athlon64 3200+ A8VDeluxeV2 512M+100G http://www.philpem.me.uk/ | Tiger: Toshiba SatPro4600 Celeron700 256M+40G

Chuck Guzis wrote: What you could probably do is remove the head preamp IC and stepper motor drivers and patch into the circuit directly. I'm not sure if that'll give you a Shugart-type FDD interface, but it might be worth a shot (on a drive with a truly buggered mechanism). Or you could build a new 1541 mainboard from scratch and mod the circuit to provide a Shugart FDD interface, which might be a bit easier. ISTR there's some stuff on the inner workings of the 1541 on Ruud Baltissen's site, including some info on the inner workings of the 1541 LSI controller. -- Phil. | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder philpem at dsl.pipex.com | Cheetah: Athlon64 3200+ A8VDeluxeV2 512M+100G http://www.philpem.me.uk/ | Tiger: Toshiba SatPro4600 Celeron700 256M+40G

Roy J. Tellason wrote: You could do something similar to the "IDEfile" interface - build a box that emulates a 1541 and put a menu system on it. The big problem would be with copy-protected software that used half-track scanning, code upload and other nasty tricks. Oh, it was a gate array? I knew it was some custom chip, I just wasn't sure if it was a custom LSI or a gate array... It certainly has a Commodore house part number on it IIRC. You could probably stuff that lot into an FPGA, but I don't know if anyone's done a cycle-accurate 6522 HDL model yet. There's certainly free 6502 models out there though - Free6502 (which used to be on Free-IP) and the like. I really should try and do that once I've got some spare cash lying around. Could really do with getting a C-64 and a known-good 1541 first though... -- Phil. | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder philpem at dsl.pipex.com | Cheetah: Athlon64 3200+ A8VDeluxeV2 512M+100G http://www.philpem.me.uk/ | Tiger: Toshiba SatPro4600 Celeron700 256M+40G

Philip Pemberton wrote: It's not such a big problem, if you give up the idea that floppies should be exactly 140K or whatever the normal storage was. You'll need some data structure that allows for other things, such as sync marks, sector and track ID marks and half tracks. You can then run that as a virtual 1541 with floppies. Perhaps, you could store the data as raw GCR over 80 tracks and run a 1541 emulator on top of that, and perhaps fake the timings of the track head movement and disk spin. You'll probably end up with something like 600K worth of data for a 140K floppy. :-) In the end, though, you're better off cracking the old software to run unprotected, which will make it work a lot better under C64/C128 emulators.

On 9/3/2006 at 1:32 PM Zane H. Healy wrote: But that doesn't get this disks read in the first place! It seems to me that the 1571 drives "gobble" old diskettes more easily than do other drives. By "gobble" I mean peel the oxide right off the cookie, usually accompanied by a squeal that says "your floppy's toast!" I've gotten to the point where I won't even bother with the old CDC "Precision" branded 5.25" floppies. 90% of the time, it's wasted effort, trashing the floppy and necessitating cleaning the heads of the drive. Cheers, Chuck

On Sunday 03 September 2006 11:54 pm, Cameron Kaiser wrote: The one mechanical problem that I've seen in a fairly small number of 1571s is when the bit that normally flexes as the head assembly is opened and closed actually fractures on one side. That springy bit being broken would tend to have the effect of cocking the upper head at an angle, which might account for the munching of the media. They have alignment issues much less than 1541s because the 1571 typically includes a track zero optical sensor to tell the drive electronics when it's there so you don't have that constant hammering going on. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

On Sunday 03 September 2006 02:49 pm, Chuck Guzis wrote: There were two makers of those, Alps (which I've not had good luck with overall) and Newtronics. The ones where you'd push down on the latch in the center of the drive were Alps, and the ones with the lever you'd turn were Newtronics, which always seemed to me to be a little better made. The heads on those are _not_ the same and there's a wire jumper on the board typically to set it up for one or the other. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin