Super Wh-IWM Swapper with PowerBook’s SWIM Chip 343S0029-A

Some time ago, I was working on the Super Wh-IWM Swapper (PLCC44 to DIP28 SWIM adapter). However, due to the shortage of SWIM chips (343S-0061-A, 344S-0061-A), and the fact that even when available they were extremely expensive, the project stalled. In reality, the only practical option was to salvage SWIM chips from logic boards damaged by battery bombed and corrosion.

In a way, this makes sense. The SWIM chips used from the Macintosh SE/30 through the Macintosh IIsi generation are usable, and even defective logic boards can serve as valuable donor sources for parts. *Learn more about Super Wh-IWM Swapper here.

The Option of Using a PowerBook SWIM Chip

This SWIM chip was actually removed from a PowerBook 145B

PowerBooks often suffer from a fatal aging issue known as vinegar syndrome, where the LCD screen becomes unusable even if the logic board itself is still functional. Moreover, because PowerBooks are highly miniaturized systems, most of their components are not easily repurposed for desktop machines.

What caught my attention was the SWIM chip labeled 343S0029-A used in the Apple Chip's List lists it as PowerBook 140/170. This Apple-specific part number raised the question: could it work in a desktop Macintosh? There was no way to know without testing. The package is PLCC44, which appears compatible with many desktop Macintosh systems, so expectations were high.

Immediate Testing

I installed the 343S0029-A into the Super Wh-IWM Swapper and powered it on.

It booted with no issues.

Just to be sure, in addition to the actual floppy drive, I also checked whether it could be used using BMOW's FEMU.

The chip worked flawlessly. A 1.4MB floppy booted without any issues. This confirms that the PowerBook-specific 343S0029-A SWIM chip is fully compatible.

You can sometimes find these PowerBook logic boards at low prices on marketplaces like eBay. If you have access to hot-air rework equipment, it is relatively easy to harvest the chip from the board.

When using hot air, it is necessary to protect the surrounding chips with aluminum foil or other materials to prevent them from coming off.

The Super Wh-IWM Swapper enables 1.4MB SuperDrive support on the Macintosh SE. While SuperDrive functionality is not available in certain configurations, when the SWIM chip is used in IWM mode, it supports the Mac 128K, Mac 512K, and Mac Plus. In that case, it operates reliably, although it supports only 800KB floppy drives.

If you have a Macintosh that has been sidelined due to a failed IWM chip, this may be a solution worth trying.