Sounds of the Miniscribe 3650

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3 ай бұрын

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Miniscribe 3650
Country of Origin: United States of America
Introduced: 1986
Interface: ST-412 (MFM nominal)
Capacity: 40MB
Form: 5.25 HH (1")
CHS: 809 / 6 / 17
LZN: 809
WPC: 128
Track-track: 14.9ms
Linear access: 34.5ms
Random access: 55.0ms
Rotational: 3600RPM
Media: Ferrous, inline TF heads
Disks: 3
Actuation: Stepper driven linear rack and pinion
Feedback: Interruptor
Lift/Lock/Park: Time delay park
Brake: Dynamic
Service life: 15000 hours
Related models: 3212 PLUS (1 disk), 3425 (2 disk), 3438 (2 disk RLL), 3650F (high performance), 3675 (RLL)
Failures: Media failure, interruptor slip, rack and pinion wear
Settings: aioinc.ddns.net/HOST/TH99/h/tx...
My thoughts:
Miniscribe doesn't have a good reputation, and it's because of this drive. The MS-III series was Miniscribe's first half height mechanism, and by far their most popular drive. The venerable 3650 shown here was sold from it's introduction nearly until Miniscribe went bust in 1990 - An eternity in hard drive years. This drive, like many others, did not age well. The choice of linear rack and pinion is always a bad one, as it allows the use of a more coarse stepper across more tracks. This makes data retention questionable at best, especially with wear to the rack and pinion themselves. These drives also only auto park on a specific jumper setting, and even then it is only on a time delay after 30 seconds of activity. This startled many users, and confused others who thought they had an "auto-parking" drive, which does not truly auto park on power down. The use of an interrupter does help the issue of accuracy somewhat, but only goes so far. These drives were not reliable and their continued sales as the bottom denominator 40MB unit across the entire industry put a sour taste in everybody's mouth, from CEO to consumer. This one is mine. It works, all things considered, but it still sounds like someone shaking a jar of broken glass when it's doing some particularly intense seeking. I don't recommend these drives - For this era, the NEC D5146H and Seagate Technology ST-251 are ultimately the best drives. Seagate for auto park, NEC for everything else.

Пікірлер: 30

@80sCompaqPC 3 ай бұрын

Love it! You know this is one of my favorite drives. I’ve actually had really good luck with them so far aside from one having a bad spindle (which I successfully replaced). The first one I got back in 2016 and it’s currently in one of my IBM XTs still running strong. The sounds it makes are absolutely amazing. Makes me smile every time I use it. As of right now I own four 3650s total and they all currently work fine.

@TheDiskMaster 3 ай бұрын

Yep, sadly this one has a broken head 0. It is definitely one of the noisiest drives in my collection! I think you will enjoy the upcoming video on the Miniscribe 8450 as well. It sounds like a miniature 3650!

@80sCompaqPC 3 ай бұрын

@@TheDiskMaster Looking forward to the video on the 8450! Would love to find one of those myself at some point.

@TheDiskMaster 3 ай бұрын

@@80sCompaqPCThey are indeed very hard to find. Just did a Livestream in the discord where some users picked out what drives I recorded next, so you will see a few of those too

@RetroTechChris 3 ай бұрын

YESSSS!!!! I had one of these growing up, and I think I had mentioned when we talked last that sometimes it wouldn't spin up, and sometimes it felt like it would spin out of control if left alone! Thanks for making this!

@TheDiskMaster 3 ай бұрын

Glad you like it! The 3650 is a classic drive. It's possible you had another MS-III, though, possibly a 3425 or 3438? If you were really lucky you might have had a 3675.

@RetroTechChris 3 ай бұрын

@@TheDiskMaster trying to reach back into the confines of my brain, and I am PRETTY sure they were 3650s... I do recall the capacity was around 42 MB.. two partitions under DOS 3.3, one around 30MB and one around 10MB. But this would have been 7th grader me, so who knows!

@TheDiskMaster 3 ай бұрын

@@RetroTechChrisThat would have definitely been a 3650, then.

@HiFiasco 3 ай бұрын

It always seemed strange to me that as prolific and successful a disk manufacturer as Miniscribe was, so many of their early mass produced drives performed their head calibration by basically ramming the head actuator into the stop, kind of like the Apple II floppy drives. Apple's argument for the design at least was cost savings and eliminating the need for a track 0 sensor... I wonder what Miniscribe's argument for this would have been since the optical interruptor on the stepper spindle is effectively serving that function if I'm not mistaken. Never made sense to me.

@TheDiskMaster 3 ай бұрын

The rotary interrupter is actually a hideously crude and almost useless servo positioning feedback. Because the stepper makes several full rotations (because of the rack and pinion actuator), the flag will pass the sensor I believe 3 times. It indicates track 0 at the furthest outward position, but it gives feedback for two additional positions further inward, which help the drive keep track of where it's supposed to be. This was an early 80s cost reduced design that got carried into 1990 when they got bought out by Maxtor after the fraud. The calibration here rams the heads against the inner stop because it is parked in the landing zone. If you don't park the drive, it does a completely different seek test that does not involve the end stop. The first thing the drive does is seek inwards to the first trigger of the interrupter sensor. I believe the number is about 200 steps, but I could be wrong. The flag interrupts the sensor, the drive then rotates backwards until the sensor is blocked, then does a fast seek to track zero. In this case, the first seek "fails," because the flag is already past the sensor in the landing zone. Then the drive seeks backwards to the sensor, which indicates that the heads are in their last rotation. The drive knows exactly how many steps it should take to the next trip of the sensor, the second trip, and the final third trip at track 0. This means that the drive can detect seek errors pretty easily, and performs a basic calibration of the initial location of the heads.

@HiFiasco 3 ай бұрын

@@TheDiskMaster I'm certainly no expert with this stuff, but that's great info. I actually have 3 Shugart 604s; the third one it appears that somebody messed with the interruptor position or else there's some issue with the servo positioning electronics. I got tired of messing with it!

@TheDiskMaster 3 ай бұрын

@@HiFiascoWow, three?? I managed to get one from a gentleman who couldn't fix his (over speed due to control board failure), one from a gentleman on VCF (works but noisy). Where did you get your three from? I love fixing up old drives.

@HiFiasco 2 ай бұрын

@@TheDiskMaster It was years ago but if I'm not mistaken they came from Weirdstuff Warehouse in San Jose (awesome place now unfortunately only a fond memory.) Had to grab them when I saw them as they were some of the more distinct units in the lot next to all the boring Seagates.

@TheDiskMaster 2 ай бұрын

@@HiFiasco That's a shame! Many a computer retailer with old stock is disappearing these days, it's rapidly becoming a dying industry. I'm sure the SA-600s looked totally unique among all the Seagates, for sure!

@bobjoe2827 3 ай бұрын

These drives aren't as bad their reputation makes them out to be. The most common fault is the damper slipping out of alignment, which is fairly easy to fix. I haven't owned a MiniScribe MS-III that had a head crash, just bad boards and slipped dampers. I will say that it is far easier to find a 3425 in working order than a 3650, but the 3650 still beats a Kalok or a Rodime (3.5 inch) drive.

@TheDiskMaster 3 ай бұрын

This one had a head crash and slammed head 0 off the arm, sadly. The outer component of the stepper is called an interrupter, not a damper. It does no such damping of vibrations, it only serves to (as the name suggests) interrupt or break the beam of the optical sensor for positioning information. Because of the multiple rotations from the rack and pinion actuator, this is actually used as very very crude feedback.

@bobjoe2827 3 ай бұрын

I referred to it as a damper because it resembles the dampers used in HVAC systems that I wire up where I work (as an electrician). Terminology aside I still say these drives are not as bad as many of the early 3.5" hard drives.@@TheDiskMaster

@TheDiskMaster 3 ай бұрын

@@bobjoe2827I suppose that's true, they probably were better built early on than the 3.5" stuff that followed. In terms of hard disks, I have a few that actually have liquid dampers on the actuators, hence my confusion.