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Feb19 2024, Notice of change in shipping method: Cards can be sent by international registered mail from Japan, but there is a very high possibility that this product will be considered an electronic component and will be returned. Therefore, we are no longer able to send this item by registered mail. Sorry for the inconvenience.

Many of our products have simple and interesting ideas, but this one is even simpler and innovative.

This Fat Mac Switcher is an item that can switch Mac128K to 512K or Mac512K to 128K with a single switch. *For 512K, optional adapter board is required.


Instructions here


It features:

-512K and 128K switching is possible. LED lights when 512KB is used

-Supports ROM-inator Resurrections

-Supports BMOW FloppyEMU

-Support SYSTEM 6.0.8 (at 512KB)

-HD20 support *FloppyEMU can also be used


Install on Mac128K

In this case, you need to replace all 16 memory with 41256 to 512KB. Assuming that's the case, attach the Fat Mac Switcher to the open pin header footprint at position E3 on the logic board. *The only thing that needs to be processed at this time is to cut one place on the router that connects pin 1 and pin 2. This is absolutely necessary to release the pulled-up DRAM pin 1.


Install on Mac512K

Install it in a position near the keyboard jack. Remove all the parts circled in red in the fourth photo, AS253, C51, R42, R40, and R41. Absorb the right side of the W1 jumper pad.

Solder the Mac512K adapter and the Fat Mac Switcher first. Attach a pin header to connect the logic board to the Mac512K adapter. 16 pin on the AS253 position and 1 pin on the right side of W1. Install the adapter.


Fat Mac Switcher Board, 18 USD

Option: Mac512K adapter, 6 USD

*Solder the pin headers and switch by yourself.

SMC Fat Mac Switcher

  • This product is sold as a kit. Solder and install yourself. We are not responsible for failure of the computer you install, failure of any other equipment, or your own injury or death.

    Please work carefully.

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