Tecmar Mac Drive (10 MB) A serial hard drive?! (The first Macintosh external hard drive)

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
Hey all,

I wanted to share something neat I picked up at VCF Midwest this year, a Tecmar Mac Drive, perhaps the first external hard drive for the Macintosh. This drive uses a serial port to connect to the Mac, and some software shenanigans to get around the storage size limitations of the initial Macintosh file system.

1758641480243.png
1758641616697.png



The seller, Peter, who's a fan of the channel, graciously accepted my $40 offer for this hunk of metal. And boy, is this thing a chonker! It took the combined strength of me and @eric to open the case. Inside appears to be a 10MB MFM hard drive by Tandon, model TM 502. Despite not wanting to risk blowing the two RIFA caps in the unit, which looked a bit cracked, I was gently peer pressured into turning the drive on.

Thankfully, no explosions happened! The drive spins up, and the red light on the front blinks periodically. I can't see or hear the head moving. Although when it's off, the greased wheel toward the front of the drive allows the head to move.

1758641832873.png



It didn't come with any cables, but I used a straight through serial cable from the free pile to plug in the drive to my Mac 512k. However, the Tecmar software (we tried multiple versions) simply say the drive can't be recognized. It's unknown if that means it can't see the drive, or if the drive isn't formatted, or what.

1758642126806.png



So I'll have to tinker with it more... but I'm curious, has anyone else owned this kind of drive?❓

They made a model that had a smaller drive inside, but also had a removable SyQuest cartridge drive, which is cool. Apparently the model I have is the 2nd revision, as it has a 2nd serial port for plugging a printer into. BTW, the paper taped to the top of the machine says to plug the hard drive into the Modem port of the Mac, and plug the printer into Serial 2 on the hard drive.

The drive has two layers of boards (at least) inside to convert it the thing to serial. Apparently some reports indicate that the drive can be converted to SCSI. There is a 50-pin ribbon cable on one of the boards, but I'd like to inspect the chips further to determine what signals actually may be being sent through it. Also, the software tricks to make this thing into multiple partitions may simply not work if connected via SCSI? Who knows...

1758641905941.png



I did end up replacing the two RIFA caps, just in case. The drive spins up and sounds normal, but again the head doesn't seem to be accessing. Perhaps this is only done once the software sends a command? Or maybe something inside isn't happy. 🤔

Either way, enjoy this chonk from 1985!

Update: I got it working! 🎉 Check out this post.

-Steve
 

Attachments

  • 1758642140777.png
    1758642140777.png
    777.9 KB · Views: 23
Last edited:

Hypertalking

Administrator
Staff member
Founder
Sep 4, 2021
19
11
3
Slightly dumb question. Did you try the apple HD20 driver? I doubt it would work but might be worth a try just in case?!
 

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
Slightly dumb question. Did you try the apple HD20 driver? I doubt it would work but might be worth a try just in case?!
That's a good question! This drive I believe was also capable of working with the Mac 128K, where the HD20 needed the 512K to work.

One of the original BlueSCSI System images I booted from had that driver, but it didn't seem to do anything.

From what I've read, this uses a special driver which loads as the system boots, and then it can mount the drive. However, the versions I've downloaded don't seem to see the drive.

The drive seemingly wants to work, although that could be my own false assumption. This is the first MFM hard drive I have, so for all I know it's very angry and the red blinking light means "nope!" 😅 But I'm open to suggestions. I did take a quick visual peek inside of the lid of the hard drive and it looked to be in good shape with no scratches, etc.
 
  • Like
Reactions: Hypertalking

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
Worked with a 128k?! Bonkers
Yep! They had to use volume shenanigans to get around the maximum storage sizes of the original system software, hah!

This MacGUI article states:

"You can partition your MacDrive in up to 20 volumes. Of these 20 volumes, you can mount two at a time on the Macintosh 128K, or four at a time on the Mac 512K. Wow, aren't you glad you spent the extra money to get a 512K Fat Mac?
Smile
"
 
  • Like
Reactions: Hypertalking

JDW

Administrator
Staff member
Founder
Sep 2, 2021
2,198
1,806
113
54
Japan
youtube.com
I vividly recall seeing the "Tecmar Sweetens Apples" full page ads in my early MacUser magazine issues back in the day. I recall thinking, "Man that thing is massive!" even back then. But, Steve, after seeing your photos, that thing looks even bigger! 😅

1758677554011.png



I have a GCC HyperDrive 10MB kit, which is first edition and uses an MMI drive, straight out of the same era as the TecMar. Of course, you seem to have a full-height drive, but as shown in the Ad above, they did have the smaller edition 10MB half-height drive. Not sure if those were MMI. Maybe not.

My Flickr account has photos of my drive kit:

A year ago, I fired up my Mac512 with the HyperDrive and it wouldn't boot. Since my LED is similar in function to yours, the way it lights may be similar or the same as yours...


I later had to use the HyperDrive software to reformat the drive, and then put a System Folder on it, and then it started booting. I doubt GCC's software would format your drive because the controller is different. You would probably need to track down the all too elusive TecMar software disk.

Mac128 and I were discussing the topic of the TecMar drive software back in 2009, and SUM Tools may or may not work on your drive:

This guy on EBAY is selling a different variant of the same drive, and it looks like he has the complete kit with box, so I would advise reaching out to him to see if a floppy disk was included, and even if it isn't, maybe his kit includes printed documentation which makes mention of the software.

Anyway, at 26:58 in my Public video, you can see how the drive LED responds when the drive is formatted and working properly...

 

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
The Hyperdrive one is neat! And yes, this is a bigggg drive.

Thankfully the MacGUI article I linked to above (after you log in) has THREE versions of the Tecmar software, one of the later ones should even work with System 6.

Sadly, as I mentioned above, the software simply says it doesn't recognize the drive. So it could either be not formatted, not functioning correctly, or not plugged in correctly. 🤷‍♂️ I only have the one straight through serial cable, but I'm unsure how the original was wired. So many variables!

However, since it's not a SCSI drive (seemingly), I think there are less options of trying to get this thing "seen" outside of the Tecmar software. So yes, like you suspected it may not work with the above software. I saw the same thread about the SUM software, but that doesn't seem to do it either.

I'll keep tinkering... but hopefully someone comes across my post and can confirm the cable pinout or... something. :)
 
  • Like
Reactions: JDW

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
Out of curiosity, I opened up the Tecmar "Volume Manager" software (v6.0.3) in ResEdit and looked through the alert messages.

Screenshot 2025-09-24 at 8.43.31 AM.png


This is the message I'm seeing when I use the drive. It's kind of vague, but I'm assuming it means it can't find or detect the hardware.

Not recongized.png


These are some other messages, which detail some of the functionality of the drive. Who knew the hard drive had a built-in print spooler, hah!


Unlikley expeirence issues.png
Print spooler.png
Mounted volumes.png
Volume size.png
Volume size 2.png


HFS.png
 

phunguss

Active Tinkerer
Dec 24, 2023
448
377
63
Stillwater, MN
I wonder if the platters are the rusty color or the shiny type (don't open it to find out)? When I built my first satellite solar cooker, I only had 3 5.25" platters that were shiny (near the center of the dish). The rest were all 3.5" and 2.5" platters. But it cooked hotdogs in the winter.
MyDish.jpg
 
  • Haha
Reactions: ClassicHasClass

David Cook

Tinkerer
Jul 20, 2023
74
92
18
Check the continuity on all of the serial cable pins. The MacGUI article indicates the drive clocks the serial port externally.

Use a serial breakout board to verify communication.

MacGUI said they had to leave the drive on for an hour for it to warm up and be recognized.

Try disconnecting the hard disk from the internal enclosure. I'll bet you get the same error message you are currently getting. which may indicate the issue is before the hard disk itself.

Here is the obvious checklist which I'm sure you're already considering:
  • Unplug and plug all of the cables in the drive to make sure none of them have lost contact.
  • Check the voltages.
  • At some point, you're going to have to disassemble the drive/board to check for damage or dead capacitors. If any of the chips are socketed, then pull and reinsert the chips.
- David
 
  • Like
Reactions: Mac84

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
Thanks David, I'm currently performing a number of those steps today. I didn't think of testing the enclosure without the drive connected, that's a good idea. I'll do that. (y)

I'll report back and keep everyone posted.

Here are some more photos of the boards... featuring a Z80 and a 68000!

There are certainly a lot of caps and boards to go through on this thing!
 

Attachments

  • IMG_1072.jpg
    IMG_1072.jpg
    1.4 MB · Views: 29
  • IMG_1075.jpg
    IMG_1075.jpg
    962 KB · Views: 28
  • IMG_1079.jpg
    IMG_1079.jpg
    1.7 MB · Views: 27
  • IMG_1120.jpg
    IMG_1120.jpg
    1.4 MB · Views: 25
  • IMG_1122.jpg
    IMG_1122.jpg
    1.2 MB · Views: 24
  • IMG_1123.jpg
    IMG_1123.jpg
    1.9 MB · Views: 30

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
I wonder if the platters are the rusty color or the shiny type (don't open it to find out)? When I built my first satellite solar cooker, I only had 3 5.25" platters that were shiny (near the center of the dish). The rest were all 3.5" and 2.5" platters. But it cooked hotdogs in the winter.

I only took a quick peek, but it looked like copper, similar to this "clock" someone made and posted on eBay of the same model drive. :oops:

Screenshot 2025-09-24 at 11.14.30 AM.png
 
  • Love
Reactions: phunguss

KnobsNSwitches

Tinkerer
Nov 2, 2021
41
45
18
I wonder if the platters are the rusty color or the shiny type (don't open it to find out)? When I built my first satellite solar cooker, I only had 3 5.25" platters that were shiny (near the center of the dish). The rest were all 3.5" and 2.5" platters. But it cooked hotdogs in the winter.
View attachment 23256
I did NOT expect to come across a massive solar cooker in the middle of a hard drive discussion! 😄
 
  • Like
Reactions: phunguss

phunguss

Active Tinkerer
Dec 24, 2023
448
377
63
Stillwater, MN
I did NOT expect to come across a massive solar cooker in the middle of a hard drive discussion! 😄
Well that was only my 4 foot dish. I have an incomplete 8 foot dish here with a George Foreman grill attached at the focal point. My 12 foot dish was dismantled and gone (1100 3.5" hard drive platters).
My8ftDish.jpg
 

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
Well, with the HD removed from the enclosure, but everything else plugged in, I get the same error about the drive not being recognized.

I reseated a bunch of chips (but not all) and cleaned a lot of the edge connectors. The drive spins up, but I don’t see any head movement… maybe the sensor that detects the head position has failed… or something isn’t kicking off?

I'm expecting the drive head to move / make noises when power is provided. But then again, I'm not familiar with these drives... Hmm… 🤔
 

Attachments

  • IMG_1133.jpeg
    IMG_1133.jpeg
    1.7 MB · Views: 15
Last edited:

David Cook

Tinkerer
Jul 20, 2023
74
92
18
I assume the same message even with the serial port disconnected? I mean, I suspect this message is really saying "I can't talk to the Tecmar at all".
 

Mac84

Administrator
Staff member
Founder
Sep 4, 2021
282
362
63
New Jersey, USA
www.mac84.net
I assume the same message even with the serial port disconnected? I mean, I suspect this message is really saying "I can't talk to the Tecmar at all".
Correct, sorry for not stating that above.

So currently, I get the same error if 1) the drive is plugged in and turned on with a straight serial cable connected to the modem port. 2) the same (but with the HD removed from the case), or 3) with nothing plugged into any serial port.

I'm also going to try the serial port on the Mac. I can't recall using it recently, but I'll plug a printer in and confirm that's working, etc.
 

JDW

Administrator
Staff member
Founder
Sep 2, 2021
2,198
1,806
113
54
Japan
youtube.com
I highly doubt the caps are the reason, but full disclosure, I did recap the drive mechanism in my HyperDrive Mac, in addition to its dedicated secondary PSU. But I had no issues with the HyperDrive kit prior to that

Not sure the lack of head movement is the issue. I don’t think there is any sticky goo that would prevent movement as there is in some Quantum drives. And if your peek inside didn’t reveal any rust (which I shouldn’t because it’s sealed), then the root problem is likely something else.

The HyperDrive software consists of various apps, and when I experienced the non booting, non mounting problem, most of those apps wouldn’t recognize the drive mechanism at all. I then found the correct HyperDrive app that did the low level format, and then it suddenly mounted and all other Hyperdrive apps could see and use the drive.

If that same exact drive mechanism was used in early PCs of the day, it would be interesting to see if one of those could mount it and format it.
 

Kai Robinson

TinkerDifferent Board President 2023
Staff member
Founder
Sep 2, 2021
1,290
1
1,277
113
43
Worthing, UK
Looks to be an MFM drive. I'd bet that you're right @JDW in that the drive needs to be low level formatted first.
 
  • Like
Reactions: JDW