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MEGA, and the Future of ROM-inator II

It’s my pleasure to introduce the Mac ROM-inator II MEGA, with 2x the storage capacity of the original ROM-inator II SIMM. Like the standard ROM-inator II, the MEGA replaces the stock Macintosh II series or SE/30 ROM with a programmable flash memory module. Once installed, the flash ROM takes over the Macintosh, allowing for a bootable ROM disk, new startup sound, new icons, HD20 support, 32-bit clean ROM, and other crazy customization possibilities.

I’m assembling the MEGA SIMMs as needed, so the order processing time will be longer than for other BMOW products. The standard ROM-inator II SIMM will remain available, and is probably still the best choice for most users. But for those looking for the largest possible ROM that the Macintosh II series machines can support, the MEGA is a great option.

The default ROM disk image has been expanded for the MEGA. Thanks to the FC8 on-the-fly decompression that I implemented last year, the 8MB of flash on the MEGA is enough to store the 512KB system ROM and a 12MB disk image full of classic utilities and games. The utility programs include ResEdit and some SCSI tools, which should be useful for anyone configuring a new hard disk. Both the MEGA and the original ROM-inator II SIMMs can be reprogrammed with the optional ROM SIMM programmer.

The Future of ROM-inator II

Both styles of ROM-inator II SIMM use a set of 16 megabit 5V flash memory chips to interface directly with the Macintosh bus. There’s only one manufacturer that still makes this chip, and they recently moved it to “end of life” status, with an official retirement date of March 2018. The chips are still available for now, but already the supplies are dwindling, and the price is going up. This isn’t good news for the long-term viability of the ROM-inator II products.

I may place one final order for a large number of chips before March 2018, but after that I don’t see a clear path forward. Using 3.3V flash memory would require level converters for 60-something memory bus signals, with 32 of those requiring bidirectional level conversion. That would be expensive, and difficult to physically fit and route on a 3 inch SIMM.

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 little or no space available for a ROM disk.

We’ll see what 2018 brings. Until then, enjoy the ROM-inator II hardware while it lasts!

Read 4 comments and join the conversation 

4 Comments so far

  1. Michael Engel - May 25th, 2017 5:46 am

    The GODIL, an Xilinx FPGA-based module designed to plug into a DIL40 or DIL48 socket (, uses TI’s SN74CB3T16211 24-Bit Fet Bus Switch ( for bidirectional 53.3V conversion. These ICs are available in a 4.4mm wide 56 pin TFSOP package. This might be an option for a future version of the ROM-inator using 3.3V flash.

  2. Kristian Möller - May 29th, 2017 2:32 am

    Will this new MEGA ROM fix the SIMM socket issues from the SE/30 without the rubber band?

  3. Steve - May 29th, 2017 6:13 am

    Whatever is happening with some SE/30’s and loose SIMM slots is still happening, unfortunately. The MEGA is basically the standard SIMM with 2x the memory, but is otherwise the same.

  4. Kristian Möller - May 29th, 2017 6:27 am

    Thank you Steve!
    Its not that big of a deal. I have a newly re-capped, and dirty, SE/30 that is dying to become 32-bit clean. 🙂

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