Steve Chamberlin's VGA Mac Sync-inator Gets Vintage Apple Hardware Playing with Modern Monitors

This compact adapter board provides automatic sync handling, dramatically improving compatibility with VGA-capable displays.

Gareth Halfacree
1 month agoRetro Tech / Displays / HW101

Engineer and vintage computing enthusiast Steve Chamberlin has designed a must-have accessory for anyone working with classic Apple Macintosh systems: the VGA Mac Sync-inator, which helps get the devices talking to modern monitors through the use of not just one but three different synchronization modes.

"The Sync-inator is an adapter for connecting Apple video sources (DB-15) to VGA monitors (HD-15), with active sync processing circuitry that sets it apart from typical passive video adapters," Chamberlin explains. "There's a built-in microcontroller that analyzes the incoming sync signals in real-time, automatically selects the best adapter settings, and can optionally reprocess the sync signals into a different format for better compatibility with some VGA monitors. You can even view a debug log of diagnostic and technical information about the video signal, as seen by the Sync-inator."

The Mac Sync-inator isn't alone in offering the ability to adapt the low-density DB-15 video connector on the original Apple Macintosh range, and the earlier Apple IIgs, to a higher-density VGA connector — but it goes considerable beyond simply wiring both ports up. Building on work Chamberlin showed off back in October last year, the device is an active adapter that not only allows the synchronization signal to be reprocessed one of three ways but is also capable of detecting which of the modes is required at start-up.

"In short, the Sync-inator makes it possible to use many types of VGA monitors that previously wouldn’t work with your classic Apple video source due to sync compatibility issues," Chamberlin explains. "It also removes much of the frustration that's typically associated with using passive DIP-switch VGA adapters, by using a microcontroller to automatically configure some of the adapter settings."

For devices where the video output may be suspect, the Sync-inator can also double as a debug tool: a pair of on-board LEDs light when either a composite or separated sync signal is detected, confirming the presence of a video signal even if the attached monitor can't see it, while a debug log available on a USB serial port provides feedback on exactly what that signal is and any sync conversion taking place.

The VGA Mac Sync-inator is available on Big Mess o' Wires, priced at $39 fully-assembled.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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