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Archive for the 'ROM-inator' Category

Mac ROM-inator II Restock and Partnerships

The Mac ROM-inator II is back in stock – get yours now at the BMOW Store. The ROM-inator II is a replacement ROM SIMM for Macintosh II series computers and the Mac SE/30, adding a bootable ROM disk, 32-bit cleanliness, HD20 hard disk support, and more. Read more about it at the project’s home page. This is the 1.27 mm (0.05 inch) custom SIMM thickness that works best in finicky SIMM slots like those found on the SE/30.

Policies and Partnerships

The Macintosh ROM SIMM landscape has changed significantly since I started selling them in 2016. At that time, BMOW was the only vendor making and selling custom Mac ROM SIMMs, and the “product” was a combination of hardware and software. The hardware was the SIMM PCB and flash memory chips, while the software was a unique base ROM implementing on-the-fly decompression of a ROM disk image, auto-detection of the memory configuration, a new startup chime, and more. Sales of the hardware subsidized my development work on the base ROM software.

In the last few years, several other vendors have begun selling Mac ROM SIMMs too. Friendly competition is great, but it creates a potential dilemma for me if someone buys another vendor’s ROM SIMM and reprograms it with BMOW’s base ROM in order to get the on-the-fly ROM disk decompression and other features. It could turn into a situation where my base ROM software is subsidizing another competing product. To compound the problem, I didn’t have any clear usage policy or “license” for the base ROM to say whether this type of use was OK. Furthermore my FC8 compression algorithm is free open-source, but the BMOW base ROM which incorporates it is not. This all created a large gray area.

I hope to clarify this now by making the BMOW base ROM image explicitly free for personal use with anybody’s own Mac ROM SIMM, no matter what vendor they purchased it from. This is the simplest and best way of resolving the ambiguity for the benefit of the classic Mac community. I only ask that you don’t resdistribute the base ROM image elsewhere – come back to the BMOW Mac ROM-inator II details page if you need to download the image.

For vendors who might be interested in selling a version of their Mac ROM SIMM that’s pre-programmed with the BMOW base ROM software, I’m happy to partner with you. Please contact me to discuss it. CayMac Vintage and BMOW have recently partnered to bring the BMOW base ROM to their Mac ROM SIMM hardware, which you can check out here. Exciting stuff, and I’m glad to see new energy in this space that will benefit the classic Mac community at large.

The current state of custom Mac ROM SIMM technology is the result of hard work by many people stretching back 20 years: Gamba, Jeff Walther (trag), Doug Brown (dougg3), Rob Braun, myself, and many others. I wish you exciting ROM adventures, friends!

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ROM-inator Resurrections

Good news! Kay Koba at Kero’s Mac Mods store is now selling pre-packaged ROM-inator kits for the Macintosh Plus, Mac 512Ke, 512K, and 128K. This is a recreation of the original Mac ROM-inator kit that I designed in 2015. The design is open source, and Kay’s new version is called “ROM-inator Resurrections”.

The ROM-inator replaces the stock 64K or 128K of ROM in a compact Macintosh with a full 1 MB of flash memory. Once installed, the flash ROM’s contents can be updated via software from within the running Macintosh, allowing for extensive customization. The replacement ROM adds a bootable ROM disk to your Macintosh, provides built-in HD20 disk support, replaces the startup sound, changes the Happy Mac icon, and makes it possible to edit the ROM disk or even tweak the ROM toolbox code code.

  • Startup beep is replaced by a glass “ping”
  • Happy Mac icon is replaced by a Mac wearing sunglasses
  • Pirate icon is displayed while waiting to load the ROM disk
  • ROM disk image including System 6, Mac Write, Mac Draft, and eight games
  • 128K ROM code turns a Mac 128K or 512K into a 128Ke or 512Ke

The ROM-inator is a descendant of Rob Braun’s original Mac Plus ROM Adapter and disk driver. More details about its inspiration and development are here.

When first powered on, the Macintosh will play a customized startup sound, and display a “pirate Macintosh” icon. To boot from the ROM disk, press and hold the R key on the keyboard for a few seconds. If R is not pressed, the Macintosh will boot normally from an attached SCSI disk, or wait for a floppy disk to be inserted.


The utility program Flash Tool can update the flash ROM from within the running Mac. Alternatively, the flash chips can be removed from their sockets and reprogrammed using a standard EPROM programmer.

Flash Tool

You can buy a ROM-inator Resurrections kit from Kero’s Mac Mods store. Please refer to their store with any questions or tech support needs; BMOW does not provide any support for these.

Happy ROM hacking!

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BMOW Product Updates

Mac ROM-inator II rominatorii-front-and-back

The Mac ROM-inator II is back in stock – get yours now at the BMOW Store. The ROM-inator II is a replacement ROM SIMM for Macintosh II series computers and the Mac SE/30, adding a bootable ROM disk, 32-bit cleanliness, HD20 hard disk support, and more. Read more about it at the project’s home page.

The instruction manual for the BMOW Floppy Emu disk emulator is now available in Japanese. Thanks to Kay Koba for the translation work. 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.

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Mac ROM-inator II: The Thickening

Mac ROM-inator II rominatorii-front-and-back

The Mac ROM-inator II is back in stock – get yours now at the BMOW Store. The ROM-inator II is a replacement ROM SIMM for Macintosh II series computers and the Mac SE/30, adding a bootable ROM disk, 32-bit cleanliness, HD20 hard disk support, and more. Read more about it at the project’s home page.

One small mystery has followed the Mac ROM SIMM project from its earliest days, even before BMOW took over the project from Doug Brown. Experience has found the Mac SE/30 to be much pickier about replacement ROM SIMMs than other Macintosh II series computers. On many SE/30 machines, the computer won’t boot with a ROM-inator II SIMM installed until the SIMM is shimmed or braced with clips or rubber bands. Why? Neither Doug nor I ever found a satisfactory answer. While it isn’t difficult to do, it’s an added step that isn’t needed for other machines.

Over the years, a few SE/30 owners have suggested the ROM-inator II SIMM is too loose in the SE/30 ROM socket, and one person had success manually tinning the SIMM pads to make them slightly thicker. I was never fully convinced about this theory. Why would it only affect the SE/30 and not other machines? And anyway the replacement SIMM was the same thickness as the original ROM SIMM (about 1.2 mm), to the limit of my caliper’s measuring abilities. The exact thickness is hard to pin down, since it varies slightly at different regions on the PCB, and there’s also a +/- 10% thickness tolerance from the manufacturer.

I recently learned something that made me reconsider the thickness theory. Back in 1970s and 1980s, PCB thickness was sometimes specified in mils (thousands of an inch) rather than in millimeters. 50 mil PCBs (1.27 mm) were a common thickness, but today these have all but disappeared. Now 1.2 mm is the closest standard thickness, and that’s what was used for all the previous generations of ROM-inator SIMMs.

Is it possible the original SE/30 SIMM was 50 mils (1.27 mm) nominal thickness, with a matching thickness socket, while all the other Macintosh II models used 1.2 mm nominal SIMMs and sockets? That would be a little surprising, but it could explain the behavior I’ve seen. With a 10% thickness tolerance, that means original SE/30 ROM SIMMs would be anywhere from 1.14 to 1.40 mm thick, and ROM-inator II SIMMs would be anywhere from 1.08 to 1.32 mm thick. It’s conceivable that the ROM-inator II SIMMs at the thin end of the distribution, under 1.14 mm thick, might have trouble in SE/30 machines.

It’s still just a theory, but it seems like a plausible one. I spoke to my local SIMM manufacturing partner about getting a thicker PCB, but unfortunately 50 mil PCBs were not available. To complicate matters further, if you’re concerned about differences of a hundredth of a millimeter, then you also need to consider the thickness of the PCB’s copper layer and any plating on the copper. Much of this calculation went over my head, but eventually my local partner was able to find a Korean manufacturer who could create a 1.27 mm stackup with 10% tolerance. The new batch of ROM-inator II SIMMs in the store today were made by that manufacturer.

So there you have it. If I’ve done this correctly, the nominal thickness of a new ROM-inator II SIMM should be a whopping 0.07 mm greater than before, an increase of about six percent. Will that do anything to help the SE/30? Especially when the thickness tolerance is still larger than the new increase in thickness? Honestly I’m not sure, but I’m interested to find out. Maybe it will behave the same as the ones from the previous manufacturer, which would be anti-climactic but fine. Or maybe it will provide some new clues for this long-running SE/30 ROM SIMM mystery.

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Mac ROM-inator II is Back!

The Mac ROM-inator II replaces the stock ROM in the Macintosh SE/30, IIx, IIcx, IIci, IIfx, or IIsi, adding a bootable ROM disk, 32-bit cleanliness, HD20 hard disk support, and more. I had to discontinue this little guy in February, due to unavailability of flash memory chips and heavy product support needs. I’m happy to report that I’ve found a new flash memory provider, and streamlined the product a bit, enabling the reintroduction of ROM-inator II SIMMs today.

The new version is the ROM-inator II Atom, replacing the old Basic and Mega designs while retaining the same overall concept and compatibility. The contents of the built-in ROM-disk on this 2MB ROM module have been refocused to setup, recovery, and utility purposes rather than gaming. The ROM disk contains:

  • System 7.1, with System Update 3.0 and Apple CD-ROM Extension 5.3.1
  • HD SC Setup 7.3.5 (patched to support formatting non-Apple hard disks)
  • SCSI Probe 3.3 (for troubleshooting the SCSI bus)
  • ResEdit 2.1.3

Even when booting from a regular hard drive instead of the ROM disk, you still get the benefits of 32-bit cleanliness, HD20 hard disk support, a boot menu, and custom Happy Mac icon and startup chime.

Read more about the ROM-inator II Atom at the product page, or buy one now at the BMOW Store.

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The End of the ROM-inator

All good things must come to an end, and today it’s the end of the Macintosh ROM-inator II SIMM and SIMM programmer. The DIY ROM-inator I kit was discontinued a year ago, and now the ROM-inator II is also being retired. I hate to see it go, but as I’d cautioned more than year ago, this was inevitable.

The ROM-inator II SIMMs (both standard and MEGA sizes) use a set of 16 megabit 5 volt flash memory chips to interface directly with the Macintosh bus. There was only one manufacturer still making this chip, and they moved it to “end of life” status in March 2018. Supplies dwindled, prices went up, and now they’re all gone. The 64-pin SIMM socket needed for the SIMM programmer became similarly hard to get, with only one known remaining supplier with a finite number of new-old-stock parts.

Both technical challenges might be solvable, with enough effort. Perhaps level converters with 3.3 volt flash memory could be integrated on the SIMM. The top edge of the SIMM might be redesigned with a different edge connector to fit a programmer socket that’s still commercially available. But candidly, the ROM-inator was always a somewhat poor value proposition for me, requiring more effort to maintain and support than was reasonable given its sales. I’m not interested in a big new engineering effort to redesign the hardware now.

There are also some issues on the software side that would need attention, if the ROM-inator II were to continue. There’s an unknown bug involving the SIMM programmer’s bootloader, which often causes the programmer to fail to be detected by the software. On MacOS Sierra and later, the software requires an awkward series of quitting and restarting before it will successfully connect. The driver and software application also need to be digitally signed, to shut up the warnings from the latest versions of Windows 10 and MacOS.

Smaller capacity 5V flash memory chips remain available, and I could conceivably design a “ROM-inator II Mini” with 512KB or 1MB of total storage. That would be enough for a modified system ROM with the new startup sound, new icons, HD20 support, and 32-bit clean ROM. But it would leave no space available for a ROM disk, and no way for users to reprogram the SIMM. And there’s already somebody on eBay who’s selling almost exactly that.

Thanks, ROM-inator. It’s been a fun ride!

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