SDISK II is a DISK II emulator for Apple II series. You can use an image on an SD card instead of a 5 inch floppy disk.
Connecting an SDISK II with a DISK II INTERFACE CARD, an APPLE II can read from and write to a DOS 3.3 image (NIC file) recorded on an SD card. NIC is an original format, and a NIC file and a DSK file can be converted mutually.
An SDISK II selects a NIC file whose update time (time stamp) is the latest in the all NIC files that exist on the root directory of the SD card. When there is no NIC files on the root directory, the NIC file is generated from the DSK file with the latest update time automatically. The LED blinks while generating a NIC file.
The mutual conversion between a DSK file and a 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 XP)
Mac OS (source & binary, tested on 9, 10.2 and 10.3)
You can convert a DSK file to the NIC file by dragging it into dsk2nic icon. You can convert a NIC file to the DSK file by dragging it into nic2dsk icon.
Java (tested on Java 1.7.0_25)
I implemented a Java version. Double click DSK_NIC.jar, and drop a DSK file or a NIC file which you want to convert.
Formatting the disk (INIT in 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 on the SD card. I recommend to format the DSK file with an Apple II emulator.
I recommend to skip the INIT part (line 250) of COPYA.
The disk image is write protected eather if the NIC file is read only, or if the LOCK switch on the SD card is ON.
Please be sure to format the SD card with FAT16.
If you can not mount a NIC file, remove the card and plug it again several times. Plugging it, confirm that the LED lights up immediately, and goes out.
I confirmed that an SDISK II works with an Apple II JPLUS, an Apple IIe and an Apple II GS (ROM1). Apple II ROM3 also supported (Oct.25/2013).
About Apple IIc, see the blog article Connect an SDISK II with an Apple IIc .
I've just confirmed the read, write and initialize operations with RWTS routines.
The speed of writing doesn't reach DISK II, and it depends on the kind of the SD card.
To prevent accidental data loss, please make sure you have the backup.
I designed SDISK II assuming that you use an SD card between 32MB and 2GB, but there may be compatible problems.
SDISK IIs which are shipped after October 23, 2013 have a boot loader, and you can update the firmware from an SD card. If there is an SISK2.hex file on the root directory of the SD card, the firmware is programmed when power is on. Remove the SDISK2.hex file from the SD card after you finish the update. You cannot program the flash memory more than 10000 times.
Any damage when SDISK II is used is not guaranteed in Nishida radio.
You can download the firmware source code and the schematic here.
In fact, the archive of UNISDISK firmware also includes another firmware of SDISK II which also has a SmartPort emulator.
I thank to the customers who bought the SD card reader, the former work.
I thank to everybody who have opened various technical intelligence to the public.