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Archive for the 'Floppy Emu' Category

Floppy Emu SoftSP Warning

I’m calling attention to a hardware issue with the third-party “softSP” card that can damage your Floppy Emu when the two are used with a Disk II controller card in an Apple II+ or Apple IIe. This issue creates a power-to-ground short circuit that will cause accumulating damage to the transistor structures on Floppy Emu’s interface chip. The symptoms don’t appear immediately, and it may seem that everything’s OK for days or weeks, until the Floppy Emu begins to fail irreversibly. The good news is that a simple cable modification is all that’s needed to use softSP and Floppy Emu together safely.

 
softSP Pseudo-Smartport

BMOW isn’t affiliated with the softSP card – it’s sold by a third party and is designed for use with another type of disk emulation product. It does appear to work with the Floppy Emu initially, and in recent months the Total Replay game collection has inspired a few people into using softSP with the Floppy Emu. Some popular YouTube videos even specifically recommend this combination, even though softSP isn’t designed for use with the Floppy Emu.

The problem is that softSP provides a software patch for Apple II disk controller functions, but does nothing to address the resulting low-level electrical problems on the disk interface. The softSP card contains a small ROM that overrides the built-in ROM on a standard Disk II controller card. It essentially reprograms the Disk II card, so instead of functioning as a 5.25 inch floppy disk controller, it now functions like a Smartport disk controller, which supports block-based disk I/O for disk sizes up to 32 MB. Neat! But there’s a catch.

You can’t safely connect a Smartport device to a Disk II controller card, no matter how the card’s internal logic might be modified. That includes Floppy Emu when it’s configured in Smartport emulation mode. The reason is that Smartport devices connect pin 12 internally to ground. This is how other connected equipment and daisy-chained drives know that they’re Smartport drives, and it’s essential for correct daisy-chain operation of Smartport drives with the BMOW Daisy Chainer or the Apple Unidisk 3.5 drive. For other types of Apple II disks as well as the Macintosh and Lisa, pin 12 is used for the SELECT signal. But on the Disk II controller card, pin 12 is connected to the +5 volt power supply. So when you connect a Smartport device to a Disk II controller, you create a direct power-to-ground short circuit. Ouch!

To be clear, there’s no specific hardware problem with the softSP card itself – it’s just a ROM. The problem arises when using the softSP card to reprogram a Disk II controller card, which is then connected to a Floppy Emu that’s configured in Smartport emulation mode.

 
Accumulating Chip Damage

The Floppy Emu board has a small inline protection resistor that will prevent immediate damage and failure due to this short circuit, but it’s only meant to protect against brief transients during power-up and power-down, or brief accidental mis-configuration. The Floppy Emu’s CPLD interface chip will likely not survive sustained operation in this mode, because it will cause a continuous current on pin 12 due to the short circuit, with a current level that’s more than twice the absolute maximum rating of the chip. This can eventually cause damage to the chip that will appear as intermittent disk errors or total failure of the device. Unfortunately this type of damage is cumulative, so even if you stop using Smartport mode with softSP and a Disk II card, the damage is already done.

With the continuous over-current, the insulating silicon layers between parts of a transistor can wear away, or develop small holes. At first the effect is minor – maybe the leakage current is more than it should be, or the noise margins are reduced below the spec. The chip may still work OK under normal conditions, but problems may appear under extraordinary conditions at high/low temperatures, or when the supply or signal voltages are close to the rated margins, or when substantial EM noise or voltage transients are present. A problem might cause a 0 to become a 1 somewhere, resulting in a visible I/O error, or it might cause the whole chip to stop functioning until power is turned off. As chip wear grows worse, you may start to see these kinds of problems during ordinary usage. Eventually the problems will grow so frequent that the chip is no longer really usable, or the wear will progress all the way to an internal short-circuit or open circuit within the chip itself, effectively destroying it.

This kind of chip damage can be viewed as a type of gradual wear, like wearing down the engine in your car, rather than a simple yes/no question of is it damaged or not-damaged. Even normal use causes chip wear, and chips do have finite lifetimes, but normally the lifetime is measured in decades or longer. In this case the power-to-ground short circuit is like driving your car without enough oil in the engine. It’ll work for a while, but you’ll start to notice it’s running increasingly rough, and maybe it’ll develop occasional trouble with stalls or failure to start. Then one day the engine will completely seize up and the car will no longer run at all.

 
Cable Modification Fix

A simple work-around is to sever the 12th wire of the 20-conductor ribbon cable. The red wire is number 1, so simply count wires from there and cut number 12 using a small nail or a razor blade. The resulting cable will work for softSP Smartport emulation with a Disk II controller card, without creating a power-to-ground short circuit. It will also work for standard Apple II 5.25 inch floppy disk emulation. But the modified cable won’t work for true Smartport emulation with other Smartport hardware, nor for 3.5 inch floppy disk emulation, nor for Macintosh or Lisa disk emulation. If you don’t want to modify your original ribbon cable, you can get a spare cable from DigiKey for a few dollars.

Unfortunately modifying the cable won’t undo any damage that’s already been done, so if you plan to use softSP with your Floppy Emu, you’ll need to make this cable modification right from the start. Be safe!

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Floppy Emu and Disk Daisy Chainer Restock

After a few weeks’ absence, the BMOW Floppy Emu disk emulator for vintage Apple computers is back in stock. Get yours now at the BMOW store. This is the latest version Floppy Emu Model C, with OLED display.

Floppy Emu is a floppy and hard disk emulator for classic Apple II, Macintosh, and Lisa computers. It uses an SD memory card and custom hardware to mimic an Apple floppy disk and drive, or an Apple hard drive. The Emu behaves exactly like a real disk drive, requiring no special software or drivers.

 
Disk Daisy Chainer

The Daisy Chainer adapter for Floppy Emu is now available for public sale, after a long period of limited release. The Daisy Chainer board makes it possible to insert a Floppy Emu anywhere into your daisy chain of Apple II drives, with other floppy drives before and/or after it in the chain. It provides a nice improvement in flexibility for Apple IIGS owners and other Apple II users with complex drive setups.

The Daisy Chainer is a smart device with an onboard microcontroller for decoding the drive enable signals. It automatically senses the type of disk drive connected to its downstream daisy chain port, as well as the current emulation mode of the connected Floppy Emu. Some past blog posts about Daisy Chainer development are available here: part 7, part 6, part 5,
part 4, part 3, part 2, and part 1.

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Introducing Noisy Disk

Do you miss the iconic sounds of mechanical click-clacking from original Apple II floppy drives? Does the familiar rattling of a boot floppy bring a smile to your face? Today I’m introducing a new product called Noisy Disk. This board uses a mechanical relay to create authentic-sounding disk head movements for the BMOW Floppy Emu disk emulator. Sure it’s useless, but it’s useless fun.

The Noisy Disk board attaches inline with your existing Floppy Emu cable, using the provided 6-inch extension cable. When Floppy Emu is configured to emulate a 5.25 inch Apple II floppy drive, the Noisy Disk onboard relay snaps open and shut whenever the emulated disk steps from one track to the next. It creates a symphony of disk noise that will bring back memories of 1979.

Noisy Disk is compatible with Apple II family computers while using Floppy Emu in 5.25 inch emulation mode. Nothing will be harmed if Noisy Disk is used with other computers or emulation modes, but you’ll hear strange clacking noises that don’t match the disk activity. It’s recommended to use Noisy Disk in 5.25 inch emulation mode only.

The product includes the Noisy Disk board with 2 x 10 pin rectangular input and output connectors, and a 6-inch extension cable for connecting to your Floppy Emu board.

Noisy Disk is available now at the BMOW Store.

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Seeking Daisy Chainer Early Adopters

If you’ve been waiting for a Daisy Chainer for your BMOW Floppy Emu disk emulator, I’m happy to report that it’s ready to go. The Daisy Chainer board makes it possible to insert a Floppy Emu anywhere into your daisy chain of Apple II drives, with other floppy drives before and/or after it in the chain. It provides a nice improvement in flexibility for Apple IIGS owners and other Apple II users with complex drive setups.

I have a couple of hand-assembled Daisy Chainers available for sale now, and I’m seeking a few early adopters who have time to exercise it this week with their computer and drives. I need to make sure these first units get into the hands of people who can try them ASAP and confirm compatibility with their equipment, before I move ahead with manufacturing more. If you’ve got the time and the desire, send me a note!

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Floppy Emu May Feature Update

New features are blooming like May flowers for the Floppy Emu disk emulator. This firmware update has something for everyone!

Lisa

The emulated rotation speed of Lisa floppy disks can now be manually adjusted within a range of +/- 6 percent. This only affects the TACH signal that the Lisa uses to sense the drive speed – it has no effect on the actual bit rate which remains 500 Kbps. The speed adjustment is set after selecting “Lisa floppy” as the emulation mode. Adjustments may help some Lisa owners with hardware different from my test system and who reported disk speed errors.

Apple II

  • Smartport disk images can now have descriptive names like “SMART0-game-archive.PO”. So long as the filename begins with “SMART” plus a unit digit 0 through 3 it will be used for that Smartport unit. The rest of the name is ignored.
  • Added support for 40-track / 160K 5.25 inch disks
  • bug fix: NIB disks can now be ejected normally

All computers with Floppy Emu Model C

The OLED display will be dimmed after 30 seconds of inactivity. Any disk I/O or user interaction will return it to normal brightness.

 
Download the new firmware:

Mac/Lisa firmware: mac-lisa-0.8F-F14
Apple II firmware for Floppy Emu Model B and C: apple-II-0.2I-F25
Apple II firmware for Floppy Emu Model A: apple-II-0.2I-F22

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Daisy Chainer Testing

Good news: the Daisy Chainer for Floppy Emu is finished, and working nicely in all my tests. With the Daisy Chainer, a mix of real and emulated disk drives can be combined into a single Apple II daisy chain for maximum flexibility. The real drives can be attached before or after the Floppy Emu.

I have a few Daisy Chainer boards available for sale now. Send me an email if you’re interested in getting one (use the Contact link at the page’s upper-right).

Not-so-good news: newly-assembled Daisy Chainer boards are a pain to test, and this is something I didn’t account for. A true functional test requires connecting the board to a Floppy Emu, an Apple II, and a variety of other disk drives, and then running through many different permutations of daisy chain configuration and disk emulation modes. It requires 15 minutes or more. That’s OK for a few hand-assembled units, but there’s no way I can do that for a larger production run.

To support faster testing, I’ve designed two special test boards that plug into the male and female DB19 connectors on the Daisy Chainer. These will enable some automated loopback testing of the main board using its own microcontroller. It won’t be a perfect test, but combined with some other automated tests for things like pin-to-pin solder shorts it should detect most likely assembly defects.

The problem is that in order to support the automated testing with the special test boards, I need to make some modifications to the Daisy Chainer PCB. I’ve finished that work, but I’m waiting for PCB delivery and then I need to assemble a second prototype. So it will probably be at least a month until full production of more Daisy Chainers is possible.

This is the first time I’ve ever been forced to redesign a PCB not because there was a problem with the device itself, but simply because the device was difficult to test efficiently. Lesson learned: when designing anything that you expect to build more than 10 units of, planning for testing should be an integral part of the design process.

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