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Archive for the 'Floppy Emu' Category

GS/OS 6.0.2 for Floppy Emu


If you follow the Apple II world, then you probably already know that a group of hobbyists recently released GS/OS 6.0.2 – a new version of the Apple IIGS operating system based upon Apple’s last official version from 1993. This new version includes many bug fixes and added features.

To make life easier for Floppy Emu owners, I’ve created this pre-configured GS/OS 6.0.2 hard disk image. It’s a 32 MB ProDOS disk image with GS/OS 6.0.2 already installed and ready to go. If your Floppy Emu has the Apple II firmware installed and is set for Smartport mode, then all you need to do is copy the smart0.po file onto your SD card, and power up your IIGS to begin exploring 6.0.2. Even if you don’t have a Floppy Emu, this disk image should also work with other Apple II hard disk emulators – it’s just a generic ProDOS disk image.

Some software-based Apple IIGS emulators like Sweet16 don’t like ProDOS disk images that are larger than 800K. For those, I’ve also created a pre-configured GS/OS 6.0.2 hard disk image in 2MG format. This 2MG disk image will also work with Floppy Emu, but I/O performance will be worse than with the PO disk image, so the PO version is preferred.

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New Product: Universal Adapter Extension Cable


Today I’m announcing the Universal Adapter for Floppy Emu, which improves the emulation behavior with certain Apple II system configurations. If you use the Emu exclusively with Macintosh and Lisa computers, then you won’t need this. Apple II users, check the table below to see if your intended usage would benefit from the Universal Adapter:

Emulation Type Standard Adapter Universal Adapter
   3 1/2 inch floppy disk ok-green ok-green
   HD20 hard disk ok-green ok-green
   3 1/2 inch floppy disk ok-green ok-green
Apple II, II+, IIe
   5 1/4 inch floppy disk 1437100947_ko-red [1] ok-green
Apple IIc
   5 1/4 inch floppy disk ok-green ok-green
   Smartport hard disk ok-green ok-green
Apple IIc+, IIgs
   5 1/4 inch floppy disk ok-green ok-green
   3 1/2 inch floppy disk 1437100947_ko-red [2] ok-green
   Smartport hard disk ok-green ok-green

[1] Reading the disk works, but writing does not
[2] Apple IIgs with ROM 01 can boot from a 3 1/2 inch disk

The Universal Adapter also contains a protection resistor to guard against accidental damage when switching between the Floppy Emu firmware for Apple II and the firmware for Mac/Lisa. With the Standard Adapter, if a Floppy Emu board running the Apple II firmware is accidentally plugged in to a Mac or Lisa, it could damage the Emu or the computer.

To use the Universal Adapter, set its slide switch to the appropriate position, depending on the selected emulation mode of the Floppy Emu. If the Emu is set to 3 1/2 inch floppy disk mode, then set the switch to the “3.5” position. If the Emu is set to any another mode (5 1/4 inch floppy, HD20 hard disk, Smartport hard disk), then set the switch to the “other” position. Setting the switch to the wrong position won’t harm anything, but it may cause disk-related errors.


So how does the Universal Adapter work, and how does it differ from the Standard Adapter? The Standard Adapter is a passive device that maps the 19 pins of a male DB-19 connector to the 20 pins of a male 10×2 shrouded header. It rearranges the order of the signals on the pins, but it doesn’t alter them or affect them in any way. In contrast, the Universal Adapter is an active device with an on-board IC that helps with Apple II disk connections. Because the Floppy Emu hardware was originally designed for the Macintosh, it can’t handle some Apple II disk signals correctly, so the Universal Adapter does the necessary interface work. Depending on the switch setting, the disk drive enable signal from the computer may be modified before it’s passed on to the Floppy Emu, and some signals will be forced to different voltages.

It’s OK to use the Universal Adapter with a Mac or Lisa computer, even though it’s not needed for those systems – that’s why it’s called “universal”. People who use a single Floppy Emu board with both Mac and Apple II computers may find this convenient.

The Universal Adapter is available for sale now at the Floppy Emu product page. It includes a detachable three foot extension cable (about 1 meter), just like the Standard Adapter/Cable, and it’s available by itself or bundled with a new Floppy Emu board.

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Smartport Firmware Update

I’ve posted a new version of the Apple II firmware for Floppy Emu, that addresses some issues with Smartport hard disk emulation on the Apple IIc and IIc+:

  • Fixed a display bug with ProDOS disk names on the LCD
  • All Smartport disks should now be detected during the first cold boot – no warm restart necessary
  • Apple IIc+ can now use the internal 3.5 inch floppy drive simultaneously with external emulated Smartport disks

You can download the new firmware here: apple-II-0.1J3-F6

On the Apple IIc and IIGS, you can have up to four Smartport disks, which will appear as slot 5 drives 1 and 2, and slot 2 drives 1 and 2. On the Apple IIc+, slot 5 drive 1 is the internal 3.5 inch drive, and the computer is limited to using at most three Smartport disks.

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Floppy Emu – Apple II Demo Video

11 minutes of unrehearsed video showing off the new Apple II firmware features of Floppy Emu. And you get to see what a mess my desk is.

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2 GB Smartport Hard Drive for Apple IIGS

Fancy a 2 GB mass storage solution for your Apple IIGS? Last week I released new Smartport-capable firmware for the Floppy Emu disk emulator. It can emulate up to four simultaneous Smartport hard drives, which I thought were limited to 32 MB each, but it turns out that’s not true! As Ken Buchholz of explained to me, 32 MB is the maximum size of a ProDOS volume, but the underlying Smartport protocol supports drive sizes up to 8 GB. By using a filesystem other than ProDOS that supports larger volume sizes, you can take advantage of that extra potential.

So what filesystem should you use? On the Apple IIGS, the computer must boot from a ProDOS volume, but under GS/OS 6.0.1 it can mount secondary volumes in HFS format – the same filesystem format used by vintage Macintosh computers. Of course you won’t be storing Macintosh files in that volume, but Apple II files. HFS supports volume sizes up to 2 GB, so if you combine a 32 MB primary ProDOS volume for booting with a 2 GB secondary HFS volume for all your warez, you’ll be good to go! On a IIGS with the Floppy Emu under Smartport emulation mode, this is as easy as putting two files on your SD card: a 32 MB smart0.PO containing GS/OS 6.0.1, and a larger (up to 2 GB) smart1.PO formatted as an HFS volume, containing whatever other files you want. Apple2Online has some blank HFS disk images of various sizes in their CFFA3000 area, which are perfect for Apple II usage.

The screenshot below shows a 512 MB HFS volume, with a few Apple II files stored on it. I got impatient and didn’t want to wait for a 2 GB disk image to copy to my SD card. :-)


There’s one extra wrinkle to watch out for when using very large disk images like these. Due to the way it works, Floppy Emu requires all disk images to be contiguous on the SD card. A 500 sector image must occupy the contiguous range from sector N to sector N+499, or else Floppy Emu will display an “image not contiguous” error when it mounts the image. For smaller disk images this is rarely a problem, but for a large disk image on an SD card with some fragmentation, it’s more likely to be an issue. If necessary, you can reformat your SD card, then copy the large disk image to it first, in order to guarantee it will be contiguous.

New Apple II firmware apple-II-0.1G-F4 adds support for parsing the HFS volume name of a large disk image, so it’s displayed correctly on the Floppy Emu’s LCD. Have fun!

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Smartport Firmware Release


It is done! Floppy Emu Smartport hard disk emulation for the Apple IIgs and Apple IIc is now working nicely, after way too many headaches, mysteries, and assorted debugging adventures. I’m very excited, because this completes the grand slam of Apple disk drive emulation. With appropriate firmware, a Floppy Emu board can now emulate every type of drive that Apple ever made for a DB-19 disk connector or 20-pin ribbon connector, for Apple II and Macintosh and Lisa. Hard drives, floppy drives, different sizes, densities… it does them all. That’s nine different drive types in total.

Download the new Smartport-capable Apple II firmware now: apple-II-0.1E-F4

Hard disk image #1, 6 MB software collection compatible with IIgs and IIc:

Hard disk image #2, 32 MB GS/OS 6.0.1 volume for IIgs:

As with the earlier Apple II firmware versions, use this firmware only when connected to an Apple II computer. If a Floppy Emu board running the Apple II firmware is connected to a Mac or Lisa, it may cause damage. This firmware can emulate a Smartport hard drive, 3 1/2 inch 800K drive, or 5 1/4 inch 140K drive (for any model of Apple II). For best results with 3 1/2 inch and 5 1/4 drive emulation, some systems may require an intelligent adapter board (coming soon, more info below). To switch emulation modes, press the Emu’s SELECT button during the display of version info on the LCD during startup.


The Emu can emulate as many as four simultaneous Smartport hard drives, and the size of each disk image can be up to 32 MB. Here’s a pic of a IIgs with four different Smartport volumes mounted:


On your SD card, the four disk image files should be named SMART0.*, SMART1.*, SMART2.*, and SMART3.*, where * is either PO, HDV, or 2MG. These seem to be the only formats in common use for Apple II hard disk images. If there’s another format you’d like to see supported, let me know and I’ll see what I can do.

On the IIgs under GS/OS, all four Smartport disks appear on the desktop. On the IIc there’s no GUI desktop, and my ProDOS skills are too weak to understand how to access disks other than the boot volume, but from looking at the disk I/O the IIc hardware definitely sees all four disks. I did try the Apple II Desktop GUI (MouseDesk) on the IIc, and it only showed the boot disk, so maybe it’s a software thing. The pic below shows a IIc booted from a 16 MB Smartport disk, with 32767 total blocks reported by the CATALOG command.

It’s important to note that not every Apple IIc supports Smartport disks. The original IIc ROM version 255 lacks Smartport support, but later ROM versions 0, 3, 4, and 5 all have it. The Apple IIc+ also has Smartport support. You can find the IIc ROM version by doing PRINT PEEK(64447).


So what’s changed since the previous update?

  • Increased max number of Smartport disks to 4.
  • Implemented disk writes. Read-only is boring.
  • Eliminated the “phantom 5 1/4 inch drive” that was appearing on the desktop
  • Optimized the startup behavior, so it’s fast enough for a cold boot (initial power on)
  • Added 2MG support
  • Made the status LED blink during Smartport activity
  • Implemented handlers for the CONTROL and FORMAT commands
  • Lots of hardware testing and error handling cleanup

The previous issues surrounding the STATUS command and disk size reporting turned out to be non-issues. Nothing to see here, move along.

I wasted lots of time troubleshooting a problem I’d seen before: with certain SD cards, the Emu would sometimes fail to recognize the card at startup. Minor additions or modifications to the code seemed to make this problem disappear, and it only happened with specific SD cards, and then it was intermittent. I finally discovered that the problem was related to my AVRISP mkII programmer that I use for flashing new AVR firmware. During development I would often leave the programmer connected to the Emu while running tests. I found that if I disconnected the programmer before performing any tests, the problem disappeared. I don’t have any solid explanation why that helped, but I’ll take it anyway.

The Intelligent Adapter Board. Converter. Thing.


Some months ago, I learned that 3 1/2 and 5 1/4 inch drive emulation doesn’t work 100% with certain Apple II systems, and these systems will require an adapter board with active electronics. 5 1/4 inch read emulation works fine on all systems without any adapter, but 5 1/4 writes don’t work correctly on the Apple II, II+, or IIe. 3 1/2 inch emulation works on a IIgs with ROM 01 if you boot from the emulated disk, but not if you boot from another disk, and not on a IIgs with ROM 03. Yeah, it’s complicated. Fortunately the Smartport hard disk emulation works without any adapter. For Apple II users with one of the mentioned systems, who expect to use 3 1/2 or 5 1/4 inch drive emulation, they’ll want to get one of these adapter boards. The board has a switch to select between 3 1/2 inch emulation and all other modes. The adapter isn’t necessary for the Macintosh and Lisa, though it’s still compatible with them, so you can use it everywhere if you wish.

The pic above shows a prototype of the adapter board. Initially I’d planned to call this something like “Apple II adapter board for Floppy Emu”, but that’s misleading. That name would make it sound like the board is required for all Apple II usage (it’s not), and that it only works on the Apple II (it also works on the Macintosh and Lisa). Instead, I’ll probably go with a name like “Intelligent Adapter Board”, with some footnote on the Floppy Emu page explaining who might want one and why. I had intentionally postponed manufacturing any adapter boards until I had all the emulation firmware working, to ensure I knew all the cases the board needed to support. Now that that’s done, I can start the wheels turning and should have adapter boards available for sale in about four weeks.

Beta Testing

I’ve done my best to find all the bugs in the new Smartport firmware, and test it on many different Apple II systems, under many different software programs. While I think it’s pretty solid, there’s a big difference between a single-person test and a wider release. If you have a stable of Apple II systems at your disposal, please help me out by testing Smartport emulation on as many different systems as you can. If it works, or doesn’t work, either way that’s helpful information.

Happy retro-computing!

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