ITXPlus: A ITX Sized Macintosh Plus Logicboard Reproduction

I haven’t done project thread in a while as writing is not my favourite past time but people seem to enjoy them so here it goes

ITXPlus is a Mini-ITX sized Macintosh Plus logicboard clone that can be be assembled to a working state with no original parts and is intended for new build systems in modern cases

ITXPlus features a onboard VGA output using GuruThree’s Pico based video converter, power from standard 24pin ATX power supply, a onboard 50pin internal scsi header and 4MB of solderd RAM

ITXPlus also makes used of DosFox’s discreet replacement for the Sony Sound IC and my implementation of his SCHWIM IWM bypass in a PLD as well as pgreenland / quortan’s ATTiny based RTC replacement and Porchy / Hkz / Bolle’s reverse engineerings of the Macintosh Plus PAL’s

(I hope I haven’t forgotten to mention anyone’s elses work I have used….)

As it is designed to use a SCHWIM based IWM bypass it will not support floppy drives out of the box however a expansion heder is provided with all the signals required to connect a real IWM should you want to do this

With execption of the 68000, connectors and a few other little bits the board is fully surface mount, I almost went with a surface mount 68000 too but was convinced otherwise as it means the nice gold capped ceramic 68000’s can be used

The board will look something roughly like this:

Though as you can see there is still most of the routeing work to do so things may get moved around a little

Finally to answer the inevitible question: Why base it on the Plus? why not the IIci? or the SE/30? I chose to base it on the plus simply because it can be built with no original parts, this is intended to be a project build not the fastest possible mac out there.

When finished the design will be fully open source and posted to my GitHub