Apple Hard Disk 20SC Restoration / Update

[Byte Knight]

I love anything with the old Apple logo on it, so when I found a cheap dead Apple HD 20SC on eBay, I had to have it.  And I'd been looking for something to put my MacSD in, thinking that this would be better as an external device so I could use it with both vintage Macs and Apple IIgs.

I had never retro-brighted anything before, but I found this premixed Retro-Brite gel which just applies with a paintbrush.  I kept it outside all day in the autumn MN sun, applying new coats every couple of hours, and after only one day it looked great!  Here's the before and after.





After removing the giant 5.25" dead HD, the MacSD screwed right in with the included 3D printed bracket.  I hooked up a 20mA ultra bright green LED to the corresponding pins of the Expansion Port with some jumper wires for the drive activity light.  An SD extension cable runs out of the bottom of the case since you need access to the SD card in order to add CDROM images etc.  And because the MacSD needs no external power, the power supply is really just there for weight and if you get nostalgic to hear the fan running.



Everything works well with my vintage Macs, and I've been able to get it to mount some 32MB ProDOS HD images on my IIgs, but I haven't been able to get a CDROM image working with the IIgs yet.  The IIgs recognizes that a CDROM is connected, but it can't read the CD.  However, I've only been able to test the Deluxe Ware CDROM image from Brutal Deluxe since I can't find any other IIgs CD images...

 

[cheesestraws]

Very nice!

 

[landoGriffin]

That's awesome!!

 

[ymk]

Looks good!  That's a very smooth retrobrite job.

 

[Byte Knight]

Thanks guys!

Interestingly, the IIgs can read the CDROM image if I mount it as an HD image, since it's in HFS format.

 

[ymk]

Interestingly, the IIgs can read the CDROM image if I mount it as an HD image, since it's in HFS format. 

Sounds like it needs 512 byte sectors.

 

[NJRoadfan]

GS/OS can read ISO9660 discs provided the HS.FST is installed. If using Apple's SCSI cards, you need to install the SCSICD.Driver in addition to SCSI.Manager and SCSIHD.Manager. RamFAST cards just need the RamFAST SCSI card driver (found onboard the card's ROM drive) as that handles both hard drives and CD-ROM drives in one driver.

 

[Byte Knight]

GS/OS can read ISO9660 discs provided the HS.FST is installed. If using Apple's SCSI cards, you need to install the SCSICD.Driver in addition to SCSI.Manager and SCSIHD.Manager.

I'm using a GGLabs A2SCSI which is an Apple SCSI rev. C card clone, and I've got all three of those drivers installed.   HS.FST and HFS.FST are installed too.  The Deluxe Ware CD .iso image works fine on my Mac LC III but not on the IIgs for some reason.  I can read the Deluxe Ware .dmg image as an HD on my IIgs however.  It would be nice to have some other IIgs CD images to test out, but I haven't been able to find them...

 

[Byte Knight]

Just added an RGB LED to the HD so I can monitor SCSI activity, SD activity, and Errors with one light.  If you do this, just make sure you get an LED with a common cathode instead of a common anode.

 

[Byte Knight]

I can read the Deluxe Ware .dmg image as an HD on my IIgs however.  It would be nice to have some other IIgs CD images to test out, but I haven't been able to find them...

I found a few more IIgs CD images and have the same issue.  The images won't mount as CD images but work fine if you mount them as HD images.  So I guess that's one workaround...

 

[NJRoadfan]

Because they are essentially HD images. There was no official specification for ProDOS partitions on a CD-ROM, so its really just a raw dump onto the disc. There are Macintosh HFS CD-ROMs like this too (no ISO-9660 file system present on the disc). Apple later created the ISO-9660/HFS hybrid format to allow cross platform readable discs.

https://en.wikipedia.org/wiki/Hybrid_disc

 

[Byte Knight]

Because they are essentially HD images. There was no official specification for ProDOS partitions on a CD-ROM, so its really just a raw dump onto the disc. There are Macintosh HFS CD-ROMs like this too (no ISO-9660 file system present on the disc). Apple later created the ISO-9660/HFS hybrid format to allow cross platform readable discs.

https://en.wikipedia.org/wiki/Hybrid_disc

Thanks for the explanation - makes sense now.

If anyone else wants the IIgs CD "images", they'll be up on my server soon.

 

[silvi89UD]

Hi to everyone! I’m Silvano from Italy.I’ve an awesome Macintosh plus 1Mb with original Italian system 5. I use it with an external blueHD scsi with SD card. I’ve been add a diode on the motherboard to provide power on the bluescsi without external cable. Now I’ve been bough an Apple 20SC hard drive. I’m waiting to receive it, but I have some questions….
The 20SC comes with SCSI cable and terminator and maybe works….
- Can I use it with the bluescsi too? Together.
- if I decide to use just the 20SC ( and the bluescsi just in case of emergency, if the original HDD suddenly dead ) can I connect the plus just in one of two SCSI connectors without the SCSI terminator ? ( or I have to disconnect the diode)?
Thank you very much! Bye