SmartDisk II: Compatibility

This page says what works with what, and where the limits are. For a one page answer, computer by computer, see the compatibility matrix.

1. Machines and emulations

Disk II (5.25 inch)

Machine	Result
Apple II+	works
Apple II Europlus	works
Apple IIe	works: Disk II read and write, Smartloader
Apple IIc (ROM 4)	works
Apple IIgs (ROM 01 and 03)	works: the Disk II image boots

On a IIgs, set the speed to Normal in the Control Panel when you use the Disk II emulation. The Smartloader does it for you before it starts a Disk II image.

The IIgs ROM 03 looks for a SmartPort device before it boots a 5.25 inch disk. The SmartDisk II ignores that look and lets go of the data lines when the Apple does not select it, so the IIgs reaches the Smartloader or boots your Disk II image without a reset.

SmartPort hard disk

Machine	Result
Apple IIgs (ROM 01 and 03)	works
Apple IIc (ROM 4)	works
Apple II+ or IIe with a Yellowstone card	works, with write
Apple II+ or IIe with a Liron card	works
Apple II+ or IIe with a SoftSP6 card	works
Apple II+ or IIe with a Liron Reborn card	works when the card is in Liron mode: set the DIP switch SW1 off and SW2 on, and connect the SmartDisk II to the PRIMARY connector of the card
Apple II+ or IIe without a SmartPort card	cannot use SmartPort

On an unenhanced Apple IIe, the autostart ROM boots Disk II cards only. After power up, type PR# and the slot number of your SmartPort card (for example PR#5). To tell the two IIe models apart, type PRINT PEEK(64448): 224 is an enhanced IIe, 234 is an unenhanced one.

SmartPort is the emulation most sensitive to timing. Use a good cable and keep it short.

Smartloader

Machine	Result
Apple IIgs	boots and browses; starts a Disk II or SmartPort image, or with the 3.5 inch drive restarts the IIgs from the image
Apple IIe	boots and browses

The Smartloader starts a SmartPort image by jumping to the boot ROM of slot 5. On a IIgs it starts from the monitor instead. A SmartPort card must therefore sit in slot 5 on a machine other than the IIgs. The 3.5 inch choice appears only on a IIgs.

The Smartloader sends its commands to the SmartDisk II as a sector written on the emulated disk. It needs a clean write stream: see section 2.

3.5 inch drive

Machine	Result
Apple IIgs, from a .2mg, .po, .img, .dc42, .dc or .moof image	boots
Apple IIgs, writes to the image	work with 3.5 write on
Macintosh with an external 800K drive port (for example the SE), 3.5 Mac host on	sees the drive, reads the image, writes to it (3.5 write on) and initializes a blank disk
Macintosh, 800K image made by Create disk (HFS)	recognised by the Macintosh
Macintosh, eject from the Finder	the disk leaves; the OLED shows the empty drive. Mount an image again from the file list.
Macintosh with a SuperDrive port, 3.5 SuperDrive on	experimental: 1.44 MB images, read only

You turn on the Macintosh mode with 3.5 Mac host. The setting asks first (ENTER), saves, and restarts the board, because the board prepares its lines when the emulation starts. A Macintosh reads the disk status on a different line than an Apple II does: see the 3.5 inch page. In Macintosh mode the board always steps fast and fast read is off, because the Macintosh gives up when a head step takes more than about 5.8 ms. The options 3.5 fast read and 3.5 fast seek exist on an Apple II or a IIgs only.

A 400K disk has one side only: the second side does not exist for the host.

2. Accelerators and speed

Case	Result
IIgs with a CPU accelerator, 1 MHz mode	known problem, not a fault of the SmartDisk II. The CPU writes the 32 cycle write loop one cycle late (33 cycles): an extra or a missing bit every fourth byte. Smartloader commands fail with ERR:E2. The same firmware works on a stock IIe and on a IIgs with its original CPU.
Any machine on which writes from the Apple fail	ask about accelerators first. The SmartDisk II does not accept a stream with a dropped bit.
IIgs in Fast speed, Disk II emulation	does not work. Set the Control Panel speed to Normal. The Smartloader does it for you.

3. Image formats and their limits

The file lists show only the extensions of the running emulation, in upper or lower case. They do not show hidden files, system files, names that start with a dot (the ._Game.dsk files of macOS) and names of three characters or less.

Disk II

Format	Read	Write	Limits
WOZ 1.0	yes	yes	tracks of 6656 bytes
WOZ 2.0 and 2.1	yes	yes	5.25 inch disks only; the tracks must lie in the first 1.25 MB of the file
WOZ of a 3.5 inch disk	refused		the message says it is not a 5.25 inch disk
DSK, DO	yes	yes	exactly 143360 bytes (35 tracks) or 163840 bytes (40 tracks); 16 sectors a track; the sector order is found from the content
PO	yes	yes	the same sizes as DSK
NIC (nibbles)	yes	yes	at least 286720 bytes (35 tracks of 16 sectors)
2MG	not offered		the Disk II emulation does not list 2MG files
13 sector disks as DSK, PO or NIC	not supported		16 sector tracks only

Notes:

• A sector of a DSK image that cannot be decoded after a write keeps its previous content.
• The option 5.25 write (default on) makes every image write protected for the Apple when it is off. The WOZ “write protected” flag and the FAT read-only attribute of the file are honoured too.
• WOZ images of more than 40 tracks (Lode Runner) work.

SmartPort hard disk

Format	Read	Write	Limits
PO	yes	yes	no header; the size is a non zero multiple of 512 bytes
HDV	yes	yes	the same as PO
2MG	yes	yes	the data offset of the header is between 64 and 65536 bytes; the “locked” flag makes the unit write protected; a 2MG of nibbles is refused; a 2MG in DOS order is served as ProDOS blocks and the log says so; a 2MG with no block is refused

Notes:

• The file extensions .po, .hdv and .2mg work in any letter case (Disk.Po works).
• You get four units, the four volumes of the SmartPort screen.
• A ProDOS volume holds 32 MB at most (65535 blocks). Create disk makes 32 MB images.
• A block outside the image gives an error answer to the Apple instead of stopping the board.
• A read only file mounts and the unit reports write protected.
• When you mount or replace an image from the OLED while the Apple runs, the Apple is not told that the disk changed. Restart the Apple after you change an image.

3.5 inch drive

Format	Read	Write	Limits
2MG	yes	yes, with 3.5 write on	ProDOS block order only (DOS order and nibbles are refused); exactly 800 blocks (400K, one side) or 1600 blocks (800K, two sides)
PO, IMG	yes	yes, with 3.5 write on	raw blocks, 400K or 800K, no header
DC42, DC (DiskCopy 4.2)	yes	yes, with 3.5 write on	the data must match the disk format of the header; the tags are not used; the header checksums are not updated by a write
MOOF (Applesauce)	yes	yes, with 3.5 write on, in place	GCR disks of 400K (one side) or 800K (two sides); MFM (1.44 MB), Twiggy and flux disks are refused; a file marked write protected stays so; the first write clears the CRC32 of the header; a sector or a cylinder the file does not hold is not written; fast read is off while a MOOF is in the drive
1440K (2880 blocks): raw .img, 2MG, DC42	yes, with 3.5 Mac host on	no	experimental SuperDrive; read only
WOZ	not offered		not supported

Notes:

• 3.5 write is off by default. The disk is reported write protected until you turn the option on. It is also write protected when the 2MG “locked” flag is set or the file is read only.
• The 12 tag bytes of each sector read as zeros and are not kept when the Macintosh writes.
• The sectors the host writes wait in a queue of 18 sectors and reach the card in steps. An eject or an unmount writes the queue first.
• The board reads the tracks straight from the card, so the card needs 32 KB clusters. The mount refuses an image on a card with other clusters.

Create disk

Create disk offers only what the running emulation lists.

• The Disk II offers 140K images.
• The 3.5 inch drive offers 400K and 800K images, and with 3.5 Mac host on also 1440K.
• HFS (Macintosh) volumes exist for the 3.5 inch drive only: 800K as DC42, IMG, 2MG or MOOF, and 1440K as IMG.
• ProDOS images (bootable or empty) can be 5.25 inch, 3.5 inch, 32 MB hard disk, or .moof for the 3.5 inch drive.
• A DOS 3.3 bootable image is a 5.25 inch .dsk.

The table of formats is on Create disk and image formats.

4. Copy protection

The SmartDisk II plays these copy protection schemes.

Copy protection	Status
Fat Track	Passed
Weak Bit	Passed (turn the WeakBit option on for The Print Shop Companion and Commando)
Cross-track synchronisation	Passed
Half Track	Passed
Data Latch	Passed
Timing Bits	Passed
E7	Passed
Optimal Bit Timing (below 4 microseconds)	Passed
Various Bit Counter	Passed
SpiraDisc	Passed

The Locksmith “Certify” and “Fast copy” functions work. Writing works with Locksmith 6.0, and initializing a DOS 3.3 disk works.

These WOZ titles run: Blazing Paddles, Bouncing Kamungast, Hard Hat Mike, Crisis Mountain, Dino Eggs, First Math Adventures, The Print Shop Companion, Commando, Miner 2049er II, Planetfall, Rescue Raiders, Sammy Lightfoot, The Bilestoad, Stickybear Town Builder, Take 1.

5. SD card requirements

Requirement	Detail
File system	FAT32 with 64 sectors of 512 bytes a cluster (32 KB) and one MBR partition. The WOZ, DSK, NIC, 2MG and 3.5 inch drivers refuse an image on a card with another cluster size.
FAT16, exFAT	exFAT is not supported. A card of 2 GB or less that the SmartDisk II formats gets FAT16 with 32 KB clusters, and that works.
Formatting	Use Settings > Make filesystem. Windows 10 and 11 do not format a card the right way. The function clears an old MBR and GPT, aligns the data area and checks the result. The card must be at least 64 MB.
Card at power up	The board checks the card when it starts. A card it cannot mount shows SD INVALID. A card with clusters other than 32 KB shows CLUSTER NOT 32K. Both messages leave RET open, so you can reach Settings > Make filesystem.
Card removed	The display shows SD EJECTED. When you put the card back, the screen offers ENTER to restart. The board does not restart by itself.
Card choice	Use a good quality card of a known brand.
Interface	4 bit SDIO

6. Folders and names

Limit	Value
Entries listed in a folder	255 at most, the entries “.” and “..” included. Folders come first, then the names in alphabetical order. A folder with more shows the first 255.
Characters in names	The card names are read in code page 850. A character the display cannot draw shows as “?”. Characters outside the Western European set are not handled.
Long names	A long name scrolls on the OLED. The Smartloader shows 22 characters at most.
Length of a path	A folder path of 256 bytes or more cannot be entered. An image path of 320 bytes or more cannot be selected: nothing changes and a message is shown.
New folder	30 characters at most; no leading dot, no trailing dot or space.
Favorites	10

7. Known limits

• SmartPort and a changed image. See section 3: restart the Apple after you change an image from the OLED.
• Hardware before revision 3 is not compatible with the IIgs and the IIc: the trace between IDC pins 5 and 7 must be cut.
• The SD card stops answering during a transfer. The board gives up after 0.5 seconds for a listing or the configuration and after 5 seconds for an image transfer, and reports an error.
• ST-Link. Never connect the programmer together with USB or the Apple II.

8. Things that do not work

Thing	Why
2MG on the Disk II emulation	not in its file list
WOZ of a 3.5 inch disk	refused by the Disk II emulation; the 3.5 inch emulation takes no WOZ
1.44 MB MFM disks, write	the SuperDrive mode is experimental and read only
A 3.5 inch image that is not 800 or 1600 blocks (or 2880 with a Macintosh host), or not in ProDOS block order	refused when you mount it
DSK, PO or NIC of other sizes	refused when you mount it
exFAT card, or a card without 32 KB clusters	images refused
13 sector disks as DSK, PO or NIC	the drivers make 16 sector tracks only
IIgs with an accelerator that is not cycle exact: writes from the Apple	corrupted stream; see section 2

HD20 emulation (Macintosh): upcoming. It is not available in this firmware yet.

See also: the compatibility matrix, Overview and features, Disk II, SmartPort, Smartloader, 3.5 inch drive, SD card preparation, Troubleshooting.

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