Date: Wed, 26 Mar 1997 21:24:11 -0600 From: dkelly@hiwaay.net To: mike allison <mallison@konnections.com> Cc: chat@freebsd.org Subject: Re: BSD Anniversary Message-ID: <199703270324.VAA04587@nexgen.hiwaay.net> In-Reply-To: Message from mike allison <mallison@konnections.com> of "Thu, 27 Mar 1997 19:32:55 MST." <333B2DD7.52E18EA0@konnections.com>
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mike allison said: > dkelly@HiWAAY.net wrote: > > >Apparently he's having a blast with about 3 machines SL/IP or > > PPP'ed together, each with a different OS. At least one on amateur radio, > > the others routing to that one. Lately he has been buying $5 ethernet cards > > to upgrade his network. And finally he's quit calling me 3 times/night, > > "How do you do ... in FreeBSD?" (no, his parents won't let him on the > > internet). > > > Yeah, > > we wouldn't want to encourage this kind of enthusiam with systems > integration to interfere with things he'll REALLY need to know in the > future. This kid could be another Steve WOSNIAK, and we all know how > bad that could be..... Hey! You aren't knocking Apple are you? Wozniak is one of my heros. I'll have to fire up my Limited Edition Wozniak-signature 1.75MB Apple IIgs and LodeRunner you to death. The Apple II is a damn fine machine. I cut my programming teeth in assembly on one. And then merged that with hardware when I tore into the disk drive controller. An amazing design. Woz is a genius. Anyhow, eventually I ended up with an unreliable DSDD 360 floppy drive using an unmodified $35 standard mechanism. Didn't have the tools to figure out what wasn't working as the drive apparently worked well on PC hardware but not on my interface. Borrowed a 10 MHz scope and could see a significant difference between a floppy written with a PC and one written on an Apple II. Was even more amazed at Woz's genius. Hacked on some filter capacitors on the drive's MC3370 (?) trying to make it look like Woz's circuit. Got it to work better but still not usable. Woz used a couple of LC filters referenced to -12v and got perfect performance. I didn't have -12v available or know what L's and C's he used so I wasn't able to clone it on my system. I did end up with a hacked copy of ProDOS that would read/write to Rana System's 360k drives. Gave it to a friend who let me borrow a drive (Rana was the only manufacturer to attempt to offer double sided floppies on an Apple II but went out of business about the time ProDOS appeared.) Learned how Rana signaled their drives to flip heads. Used the same technique. In my adapter between SA400 floppy drives and an Apple II disk drive card I used a state machine implemented in a 2732 EPROM. Clocked it with a free running oscillator at between 50kHz and 100kHz using a 74LS04. Basically what my state machine did was map Woz's 4 phase step motor signals into direction, step, and head commands for the SA400. Its easy to map direction and step into 4 phases for a step motor (that's what they do on the drive), but the inverse is a pain. Also detected the Track 0 signal and selected the bottom head if one tried to move to track -1 so the drive could boot and operate normally before my special software was loaded. Remember how an Apple II would pull its heads in thru 80 tracks on boot, banging it against the stops for 45 tracks? Not on my hardware hack. State machine development language was AppleSoft. Wrote the equations in AppleSoft then looped thru them for all addresses in the EPROM. Took 35 minutes to generate the EPROM image. Got a version I liked on the 7th run but didn't know it until the 8th. In spite of all that fun, I eventually got my BSE from the Mechanical Engineering department. Been doing electrical stuff ever since. Found an Apple II Plus at an auction recently. Two disk drives, joystick, and a bunch of original software. Got it for $8. We need a FreeBSD version of LodeRunner.... -- David Kelly N4HHE, dkelly@hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system.
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