in Japanese

SDISK II - DISK II emulator for APPLE II -

Tohoku Kanto Earthquake Charity Program

I will donate to the Community Chest middle half of the price. I enclose proof of payment.

Open VersionF3800 yen (with a SD card, without shipping cost)
Premium version is discontinued.



I put SD card reader for APPLE II on the market in July '09, and it got popular in an auction in Japan. It makes APPLE II to read the image of DISK II, DOS 3.3 recorded on the SD card. Naturally, the next step is writing from APPLE II to the SD card. Actually, I got such a demand from the customer.

Accessing the SD card with the same timing as DISK II is difficult with a tiny micro controller and it needs more complex hardware including a larger buffer memory. Especially, writing is severe.
However, if you make the best use of the characteristic that APPLE II waits until an address header of the floppy is output to APPLE II, the data transfer has understood a possible thing.

A lot of hurdles (in Japanese...) were got over, and, at last I made it.

You can also use this product to exchange data between DISK II and the SD card.


Connecting SDISK II with DISK II INTERFACE CARD, APPLE II can read from and write to the DOS 3.3 image (NIC file) recorded on the SD card. NIC is an original format, and the NIC file and the DSK file can be converted mutually.

SDISK II selects the one NIC file whose update time (time stamp) is the latest in the NIC files that exist in the root directory of the SD card. When there is no NIC file in the root directory, the NIC file is generated from the DSK file with the latest update time (time stamp) automatically. The LED blinks while generating the NIC file.

The mutual conversion between a DSK file and an NIC file is done on PC. nic2dsk converts a NIC file to the DSK file, and dsk2nic is vice-versa.

Windows (source & binary, tested on 98 and XP)
Mac OS (source & binary, tested on 9, 10.2 and 10.3)

You can convert the DSK to the NIC file by dragging it into dsk2nic icon. You can convert the NIC to the DSK file by dragging it into nic2dsk icon.

The speed of writing doesn't reach DISK II. Moreover, the speed of writing depends on the kind of the SD card. For your information, the comparison of the time of COPYA from/to SDISK II to/from DISK II when the card of KingMax 1G is used is shown.

2 min. 51 sec.58 sec.

This result doesn't contain the time of initialization.

About INIT

Formatting the disk (INIT of BASIC, RWTS command 4) is not fully supported. SDISK II does not actually format the image, only ignore the command. SDISK II may cause an error or consume a long time while formatting the image in the SD card. I recommend to format the DSK file with an emulator. I recommend to skip the INIT part (around line 250) of COPYA. For reference, when using KingMax 1G, "INIT A" requires the following time.

41 sec.30 sec.

About Write Protect

Although the write protect switch on a SD card is ignored, the disk image is write protected if the NIC file is read only.


I confirmed that SDISK II runs on Apple II JPLUS and Apple IIe.
I received a report that SDISK II works as an internal driver of Apple IIc.
SDISK doesn't seem to run on GS currently.

ATMEGA328 AVR is overclocked to 27MHz. All copies are tested in warm and cold condition.

I just have confirmed the read, write and initialize operations with RWTS routines.

Write-protect switch on the SD card is ignored.

If you can not mount the NIC file, try to remove the card once and plug it again. Plugging it, confirm that LED turns on immediately, and turn off.

To prevent accidental data loss, please make sure you have a backup.

Please be sure to format the SD card with FAT16.

I designed SDISK II assuming that you use a SD card between 32MB and 2GB. But there may be compatible problems.

Tested SD cards

KingMax 2G, PQ1 2G, Kingston 2G, Transcend 2G (standard SD)
KignMax 1G, Hagiwara 1G, Kingston 2G, Toshiba 2G, SanDisk 2G, Team 1G, A DATA 2G, PNY 2G (microSD)
Toshiba 64M, Panasonic 32M (miniSD)

Hardware Connections



v1.1, v1.2, v1.3
It's license is GNU GPL version 3.

v1.2: a problem with plug&play fixed.
v1.3: the problem that the head doesn't return to track 0 when pushing the reset key of IIe fixed.

Exemption matters

I produce this product personally. Any damage when SDISK II is used is not guaranteed in Nishida radio, and understand humbly, please.

Address of thanks

I wish to express my gratitude to the customer who buys the SD card reader of the former work.
I wish to express my gratitude to everybody to whom various technical intelligence is open to the public on the Web.
I wish to express my gratitude to everybody of the author of various books written about APPLE II in the past.