Post B6dkEFmVLbjnGEoPZI by tubetime@mastodon.social
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(DIR) Post #B6Cmjf8G66FzVEAqiO by tubetime@mastodon.social
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ahh, the HP 9133A - the largest and heaviest external 3 1/2" floppy drive ever built. let's get it working! 🧵
(DIR) Post #B6CmjfeWAA3r7HGbzs by tubetime@mastodon.social
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whoops, surprise hard drive inside! this one is a Seagate ST-506, a MFM drive with a whopping 5MB capacity!
(DIR) Post #B6Cmjfwx3co42RtKjI by tubetime@mastodon.social
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after taking out 894375037 screws, the actual drive reveals itself.
(DIR) Post #B6CmjhynVjTIKklpsu by tubetime@mastodon.social
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oh yeah, the hard drive has a controller board on top of it. and on the controller board is this super weird potted electronics module. i'll have to look into that later.
(DIR) Post #B6Cmjil0cU2IkHKL20 by tubetime@mastodon.social
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the floppy drive is the extremely ancient Sony OA-D31V-1. it's not the first one to come out. more like the second one.
(DIR) Post #B6Cmjl12Ds2lkYqAHw by tubetime@mastodon.social
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transmissive optical sensors hate dust bunnies. they'll produce false readings, so they must be cleaned!
(DIR) Post #B6CmjlmtLwKC8zENsm by tubetime@mastodon.social
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a single-sided 3.5" drive head is something you don't see every day. they were never that common.
(DIR) Post #B6CmjoTrL9soUpLj8K by tubetime@mastodon.social
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i'm taking it apart this far because the drive mech needs to be cleaned and relubricated. the old grease hardens and makes the mechanism go sticky, so you'll be able to insert a disk, but when you try to remove it, it'll tear the head right off!
(DIR) Post #B6PJko5Pv6KlwnW8ki by tubetime@mastodon.social
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and it tests good! the weird 26-pin HP interface is natively supported by my Floppy Exerciser board (https://github.com/schlae/FloppyExerciser)
(DIR) Post #B6PJkoIX8KpGbTecCG by tubetime@mastodon.social
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on to the surprise hard drive. but, no surprise, it won't spin up and pulls a bunch of current on 12v. hmmm.
(DIR) Post #B6PJkoUwOCkbDxSWXI by tubetime@mastodon.social
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the motor won't move. I think it is stiction. ugh.
(DIR) Post #B6PJkohhckxVrXQiQa by tubetime@mastodon.social
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yeah all the heads are stuck. trying a heat gun now...
(DIR) Post #B6PJkosKzDSwOWPD0K by tubetime@mastodon.social
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it spins, but it sounds bad. not much hope for this drive, unfortunately.
(DIR) Post #B6PJkp2GOJPCtJ38TY by tubetime@mastodon.social
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the Gesswein MFM emulator was able to capture a flux transition dump! i used their mfm_util to analyze it, and it is a very odd format: check out the command line:--format EC1841 --sectors 32,0 --heads 4 --cylinders 153 --header_crc 0x0,0xa00805,32,4 --data_crc 0x0,0xa00805,32,4 --sector_length 256
(DIR) Post #B6PJkpFNbXthXzBbv6 by tubetime@mastodon.social
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example output of the analyze command... some bad sectors, but a lot of good ones!
(DIR) Post #B6PJkpOb3HGo0ZUyHo by tubetime@mastodon.social
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output of 'strings' shows some cool stuff!
(DIR) Post #B6PJkpYATgvUUFycCm by tubetime@mastodon.social
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the HPIB verification program for the HP5005B signature analyzer. wild
(DIR) Post #B6PJkpfy0hAGsRcqMS by tubetime@mastodon.social
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@dgesswein , who authored the MFM emulator tool i am using for this task, reached out. i updated the software to the latest version (i was tragically out of date). got a new dump. only a few bad sectors this time, and none on track 0!
(DIR) Post #B6PJkpptPn6XNEGlpg by tubetime@mastodon.social
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bad sectors were on tracks 37, 75, 113, and 152. the 9133a uses hardware partitioning to get four logical volumes, so these "bad sectors" are really just extra sectors at the end of each disk.for posterity, the command i used was./mfm_read --format Xebec_104527_C0_256B --sectors 32,0 --heads 4 --cylinders 153 --header_crc 0x0,0xa00805,32,2 --data_crc 0x0,0xa00805,32,2 --sector_length 256 --retries 50,4 --drive 1 --xebec_skew --begin_time 151000 --tran hp9133a_st506 --ext hp9133a_st506.bin
(DIR) Post #B6PJkq6YPqQqCu44no by tubetime@mastodon.social
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'file' is superintelligent these days. it knows about LIF disks! looks like the binary data is good!
(DIR) Post #B6PJkqHXkzDqkzCqvo by tubetime@mastodon.social
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also the drive is running very smoothly now. a few days ago it was making horrible screeching sounds but i think that was the spindle bearing. i've been running it upside down to allow the oil to warm up and drain back into the bearing.
(DIR) Post #B6PJkqOzJJB384gnXE by tubetime@mastodon.social
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digging around on this drive, i've found a bunch of software for the HP-85, including a program designed to control the HP 5005B Signature Multimeter. presumably none of this stuff has ever been preserved before.
(DIR) Post #B6PJkqZcflgTf3fI6y by tubetime@mastodon.social
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huh, i reconnected everything and plugged the drive into my HP85, and it actually works! i can read the files on it.
(DIR) Post #B6PJkqgiFPM612yxA8 by tubetime@mastodon.social
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one of the programs.
(DIR) Post #B6PJkqnnp31iN2IcDI by tubetime@mastodon.social
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unfortunately the floppy drive isn't quite working. i can't format this new disk. the drive makes a very rattly sound, so it's probably something mechanical.
(DIR) Post #B6PJkqwfI67EoWRh1k by tubetime@mastodon.social
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3 1/2" = light mode5 1/4" = dark mode
(DIR) Post #B6dkEFWuHbGETrVxFw by tubetime@mastodon.social
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got some time to take the drive out again and clean it again. i ended up having to remove this entire sliding side plate because there was still some old crusty lubricant. it is much better now. i also lubricated the head stepper worm gear.
(DIR) Post #B6dkEFmVLbjnGEoPZI by tubetime@mastodon.social
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much better, it actually formats the disk! BTW this 3 1/2" format is very odd. 600 rpm, 66 tracks, 16 sectors per track, single-sided, 270K capacity, 256 byte sectors.
(DIR) Post #B6dkEG12TZMbzJc1Ds by tubetime@mastodon.social
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why all this work? i need to work with some very early 3 1/2" disks. this example has an oval window but more surprisingly, the disk shutter must be opened manually before you put the disk in the drive!
(DIR) Post #B6dkEGMfBAf34NjHvc by tubetime@mastodon.social
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and it actually reads! at least, it recognizes the LIF volume label. the filesystem is for a different type of computer, so the HP85 doesn't show any files.