Apple II and PC Disk/File Transfers

"Or, how I learned to overcome the 'Apple II with no software' catch-22"

In early 1999, while attending a school auction, I happened upon a ROM 3 Apple IIgs, the first Apple computer I had ever owned. Little did I know, it would be over 2 years later before I had a working, usable system. The problem? Getting software from the vast archives on the 'Net to my little IIgs in a form it could use.

This is the account of the tribulations I ran across while embarking on this long (and slow, eh, work sucks) journey. Hopefully it will be of some use to others attempting to do the same.

The Problem(s)

  • 5.25" Disk Format (GCR vs MFM)

  • The first hurdle we hit is the fact that IBM PC 5.25" diskettes are in MFM format, whereas Apple 5.25" disks are in GCR format. These are two completely different methods of physical data recording, which means that data recorded in MFM format cannot be read by a GCR drive, and vice versa.

    In addition, many Apple II 5.25" diskettes are copy protected. Since the Apple II is able to control the disk drive directly via software (as opposed to the clunky serial interfaces used by the Commodore and Atari disk drives of the time), some devious manners of copy protection were developed on the Apple II. These include wizardry such as spiral formatting, ghost sectors, weak bit patterns, and tracks which return different data depending on which direction the drive is seeking. Copy protection was annoying to the user of yesterday, and it is no less annoying to the archivist and historian of today.

    There are a few types of Apple 5.25" drives.

    Apple II 5.25" diskettes are single sided, double density, 143K per side. The drive pays no attention to the timing hole, which means a double sided disk can be used as a "flippy" disk. All Apple II 5.25" disk drives read and write disks in exactly the same format, and use the same interface and control protocol; only the manner of attachment differs (ribbon cable on the Disk ][, DB-19 shielded cable on the UniDisk).

    *DO NOT ATTEMPT* to connect an Apple 5.25" disk drive of any type to the DB-19 port on the back of a Macintosh computer. It will permanently damage the Macintosh. The diskette port on the Macintosh is for 3.5" drives only.

    Only an Apple 5.25" disk drive can natively read and write Apple 5.25" diskettes. If the proper hardware is controlling it, an IBM PC 360K drive (not a 1.2MB high density drive!!) can be made to read and write Apple II 5.25" diskettes, in a limited fashion.

    There are certain limitations with using a non-Apple 5.25" drive to read or write Apple GCR diskettes. The drive must be in near-perfect alignment, and must be able to seek to track 32 (4 tracks beyond what a normal IBM drive is required to). Copy protection and custom program loaders (such as the occasional cracktro) that depend on specific characteristics of the Apple format, will most likely not work on a disk created in a non-Apple drive. For best results, use a real Apple 5.25" drive to create Apple 5.25" disks.

    In order to create 5.25" diskettes readable on the Apple, we must use at least one of the following (in order of preference):

    See below for details on each individual solution.

    5.25" Apple disks use one of three filesystems: Pascal, DOS 3.3, and ProDOS. Don't worry about Pascal; just remember that .DSK images can be stored in either ProDOS or AppleDOS 3.3 order, and so if writing out a diskette from an image in ProDOS order doesn't work, try AppleDOS, and vice versa.

    To sum up, to create a working 5.25" Apple disk, you must use hardware that supports a real Apple drive, or else hardware that can do emulated GCR-writing on an IBM drive.

    I create Apple II disks from 143K .DSK images by using a Trackstar E board connected to a Disk ][ drive. I use the Trackstar's FILETRN utilities disk image to copy downloaded disk image files from the PC side to the virtual hard drive on the Apple. Then, I format the disk in the Disk ][ using Copy II. Finally, I use DSK2FILE4 on the ProDOS utilities disk image to transfer the disk image to a diskette in the Disk ][ drive connected to the Trackstar. Works great!

  • 3.5" Diskettes

  • Only Use Older Macs with Apple II Disks

    An unfortunate interoperability concern began after the Mac II series was discontinued. Sony stopped being the supplier of disk drive units for Apple. Unfortunately for Apple, nobody else in the industry made 3.5" drives with GCR capability. (The drives Sony made for Apple were designed for GCR from the ground up.) Apple was forced to turn to modifying other vendors' drive assemblies post-production to support GCR. However, due to this last-minute hacking of newer drives, problems began to surface with exchanging disks between the newer and older systems.
    Bottom line is: don't attempt to write to a 400K/800K 3.5" diskette from amn Apple II, "Compact Mac", or Macintosh II, from a Mac that is newer than the Mac II series; even if it seems to read fine, writing to it will likely trash the disk for good.
    This also means that if you plan to use a Mac for Apple II file exchange on 400K/800K diskettes, make sure it's a Compact Mac or a Mac II.

    Apple II 3.5" 400K/800K diskettes and drives use GCR encoding just like the 5.25" diskettes, which means they can't be read on a PC. They CAN be read and written to on older Macs, however. A Compact Mac such as an SE/30 makes a great 'proxy' for transferring software and documents to the Apple II.

    Apple 1.4MB drives can also read and write MFM, so 1.4MB Apple disks CAN be read and written to on a PC with proper software. This includes the 1.4MB drive on all newer Macs as well as the 1.4MB "SuperDrive" for the Apple II.

    There are two different 3.5" disk drives for the Apple II; both of these can be hooked up and used on a Macintosh DB-19 floppy port. Each supports 400K single-sided and 800K double-sided double density 3.5" diskettes. Don't use high-density diskettes in these drives; even though you might get them to format down to 800K, the data on them won't last for long.

    It is trivial to tell a UniDisk 3.5 apart from an Apple 3.5 Drive at a glance; the UniDisk is glacier white, while the Apple 3.5 Drive is the same beige color of the Apple IIgs. Also, on the Apple 3.5 Drive, the access light and eject button are all in a row with the disk slot; on the UniDisk, they are offset some.

    Watch That UniDisk Interleave

    There is a small interoperability concern with the UniDisk 3.5. Since the UniDisk always operates at a given speed due to its built-in controller hardware, disks formatted for the UniDisk are generally formatted with a 4:1 interleave, which is the optimal interleave for the UniDisk 3.5.

    However, on the IIgs, disks in an Apple 3.5 Drive are commonly formatted with a 2:1 interleave, since the Apple 3.5 Drive is under software control, and the IIgs's zippy 2.8MHz 65c816 can easily keep up with the transfer rate from a 2:1 diskette. (Compared to the 1.02MHz 6502 in the //c with UniDisk.)

    If a disk formatted at a 2:1 interleave is used in a UniDisk 3.5 drive, the UniDisk wastes tons of revolutions as the tight interleave constantly overflows its buffer. Thus, disk access will be pretty slow, and ProDOS may even start throwing up its hands and walking away at times if the UniDisk 3.5 is taking waay too long.

    Moral of story: Don't use a 2:1 disk in a UniDisk 3.5. If you need interoperability with a UniDisk 3.5, format your disks with a 4:1 interleave. It will be only marginally slower on an Apple 3.5 Drive, but you'll thank yourself when you use the UniDisk 3.5.

    Apple has two filesystems for 3.5" diskettes, MFS and HFS.

    MFS ("Macintosh File System") is the ancient, deprecated filesystem used on the 128K Macintosh and the Macintosh-512 400K single-sided diskettes.
    Tip: It is possible to make an 800K MFS disk by erasing an 800K HFS disk on an older version of Macintosh System Software.

    HFS ("Hierarchial File System") is the 'modern' filesystem still used in MacOS today. It has much better support for large drives, removable media, etc.

    GS/OS and ProDOS can read both 400K and 800K MFS and HFS disks. If you have a SuperDrive and a controller for it, you can also use 1.4MB disks in your Apple II.



    network boot on appleshare volume

    network boot VIA appleshare

  • Apple II vs PC vs Mac - Filesystems (AppleDOS/ProDOS vs FAT vs HFS)

  • Apple - ProDOS/AppleDOS/GS/OS PC - FAT Mac - HFS

    Shrinkit - Chicken And Egg

    Prodos File Types

    Prodos minitutorial

  • Those Forking Macs

  • One detail that is quite annoying about using a Macintosh in a heterogenous computing environment, is its propensity to add resource forks to every file that is created or accessed. This is especially annoying when preparing files for transfer to an Apple II, because some specific conditions must be met for the Apple II to be able to use the file.

    As we mentioned before, the ProDOS file type (BIN, SYS, TXT, etc) must be properly set before ProDOS can use the file. Another condition is that the file must be a "standard file", meaning that it does not contain any resource forks. If the file has a resource fork, even an empty one, it is tagged an "extended file" by ProDOS and cannot be opened except by GS/OS.

    Unfortunately, the Macintosh will create a resource fork whenever a new file is created, even one that is extracted from an archive.

    The Solutions

    Apple2PC or Serial Transfer

    Trackstar (with software and docs here)

  • Macintosh LC Apple //e Emulation Board

  • This is a card that goes into the PDS slot on an LC-series Macintosh. It includes an Apple-//e-on-a-chip, as well as a connector for an external disk drive and joystick. The emulated Apple //e can use many of the resources of the Mac as its own, such as emulating a SCSI hard drive, a realtime clock, mouse, memory, network, etc. It can use the internal 3.5" drive of the LC as an emulated SmartPort 800k or 1.4MB drive; however, compatibility with an actual UniDisk 3.5 is limited and some copy protected software will have problems.

    The Apple //e Card requires an LC-series Macintosh with System 6.0.8 through 7.5.5. No higher or lower System Software is compatible, and no other Macintosh architecture is compatible.

    More information here: iie_card_faq.html or iie_card_faq.txt

    Here is the PDF documentation for the //e Card: full (900k) or text-only (170k).

    Grab the software documentation and needed files to boot the virtual //e:

    2.2.1 is the last official release. The 2.2.2d1 version is a maintenance release from 1994.

  • Apple PC Transporter Board

  • I don't know much about this board. It emulates an IBM XT-compatible computer in your Apple II, including CGA display, keyboard, mouse, etc.

    It can apparently write MS-DOS filesystems onto diskette through an Apple drive, but the low-level format of the diskettes remains Apple/GCR, so it can't be used to transfer files to a PC. However, it appears that you can hook up a PC 360K drive to it, so maybe more things are possible.

    The best source of information currently is: http://osites.tripod.com/transport.html.

    A newsgroup posting with some great info is archived here.

    Lots of PC Transporter related information and software (including the driver software) in this zip file.

  • Copy II PC Deluxe Option Board

  • The Deluxe Option Board was made by Central Point Software in 1987. Its primary purpose is hardware-based duplication of IBM PC copy-protected software diskettes. It accomplishes this by being installed in between the standard PC (NEC PD765) floppy controller and the floppy drive. When the Option Board is active, it cuts off the PC floppy controller entirely and uses its own logic to control the drive. This way, it can accomplish functions that the NEC controller was never designed for (and thus, copy protection artists would assume that these functions would not be available when designing a protection scheme).

    The Option Board isn't incredibly handy in our Apple II discussion, but it is worth nothing that it can duplicate Apple GCR diskettes on a standard PC 360K floppy drive. (Not Apple II copy protected disks, however.) It can also read and write disk images, which can be handy as a quick way to back up your scads of rotting 5.25" diskettes.

    The Option Board also has a unique ability to read and write Macintosh MFS 400K and HFS 800K 3.5" diskettes. This is accomplished through command line utilities that are similar to regular DOS file manipulation commands. (MFORMAT, MCOPY, MDEL, etc.) MFS was the "Macintosh File System" used on the early Macintosh 128K and Macintosh 512K models. HFS is the newer Macintosh filesystem that is still in use today. A IIgs with GS/OS should be able to mount both filesystems, so here's another way to get files from your PC to your Apple and back.

    See the Deluxe Option Board pages for more information and software.

    Mac (if have shrinkit)

    Links to other sites with Apple II information and software: