View Full Version : Review: SD Disk II hard/floppy drive emulator for Apple II

14th December 2014, 22:43
I was in a market for a reasonably priced no hassle mass storage solution for my Apple II, when I came across with the SD Disk II Emulator for Apple II (http://www.ebay.ca/itm/SD-DISK-II-Emulator-for-APPLE2-/281475005369?pt=US_Vintage_Computing_Parts_Accessories&hash=item418937bbb9). The developer, Ian Kim manufactures and sells these cards on regular basis and he also maintains a development blog (http://quick09.tistory.com/). It is basically an SD based hard drive and floppy drive emulator. The card can operate either in in hard drive mode or floppy drive mode, emulating two simultaneous hard drives or two simultaneous floppy drives. Image files are simply copied over in PC. Image can be selected either by using a control dial that comes with the card or via bluetooth, using a terminal program in either PC or tablet.

When I purchased the card, it had not been verified to work with the Apple IIGS, only with II, II+ and IIe. I decided to take a chance and get it anyway with the intention to sell it forward in case it wasn't compatible. Here is the card installed in my Apple IIGS.
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The card came with an SD card that was pre-loaded with software. The card was in FDD mode by default so the IIGS booted into Tetris. I installed BlueTerm into my Nexus tablet and was able to connect to the card easily. There was a few configuration changes to be made in BlueTerm to display the contents correctly. There is a pretty good documentation that goes through the installation of the card and setting up the connection.

The mode can be changed from the terminal with a simple command and then you simply just load the image and reboot. The IIGS does indeed work in HDD mode but only with ProDos images. An image containing GSOS just failed to boot. ProDos16, which is the predecessor of GSOS will however boot. The reason to this is that the GSOS is 16 bit code whereas ProDos16 is still 8 bit code.

I had already contacted the seller during the purchase that the card would be going into a IIGS and that I would be glad to report my findings, if he wanted. He accepted my offer gladly. I reported my findings and to my surprise he responded that he's going to purchase a IIGS of his own and get it working with it. My surprise was even bigger as after two weeks he had a working firmware and ROM bios that I could try out.

Upgrading the firmware was a simple matter as the file just needs to be copied into the root directory of the SD card and hold two buttons on the control dial during bootup. The ROM bios on the other hand was on an EEPROM and that needed to be flashed. Luckily, I am in possession of a Willem programmer, so I was able to reflash the chip. As you can see, the GSOS now boots nicely.
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GSOS boot time from powerup to desktop takes 1 min 10 sec. My GSOS installation isn't vanilla so that might add up to the booting time. Some of the other mass storage solutions for the IIGS are faster but that's not that big of a deal for me. Have to try to make a vanilla setup of GSOS to see if it makes any difference in boot time.

I haven't yet tried using two images at the same time. I have also Unisdisk Smart port emulator, which can also handle both floppy and hard drive images. The GSOS bootup is slightly faster with SD Disk II than with Unisdisk. Reading and writing files is pretty much in par with other 16 bit computers from that era. Here are a couple of pictures from the file copying from Unisdisk to SD Disk II.
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Overall, I'm pretty happy with the SD Disk II. Ian has been really going the extra mile to get it working with the IIGS. It may not be the fastest but it's hassle free and in my opinion a good value for money. The terminal connection via bluetooth is an added plus as there are no cables dangling outside the case. There is the control dial of course but you basically need it for upgrading the firmware. Otherwise everything can be handled through the terminal wirelessly. Operation is easy and the card is well documented and for the time being constantly upgraded and well supported. If you're looking for a mass storage solution for your Apple II, this may be a good option to consider.

12th January 2015, 11:08
Thanks for the review! I might get one myself. Right now I have a working GS/OS setup with a Apple SCSI card clone I got from the other bay (seems to be new production) and an old external SCSI drive.

12th January 2015, 11:17
Thanks for the review! I might get one myself. Right now I have a working GS/OS setup with a Apple SCSI card clone I got from the other bay (seems to be new production) and an old external SCSI drive.
Have you been happy with the clone SCSI card? That was my other option but I opted for the SD card solution mostly due to the availability of Medias. I was also after a completely internal solution and the SCSI card would've required either an external media or a custom adapter cable.

Are you aware of this SD to SCSI adapter card (http://shop.codesrc.com/index.php?route=product/product&product_id=57)? It'll probably connect nicely to the external SCSI port with a gender changer. That would've probably been my choice pf media, if I had gone with a SCSI card.