A little personal history: Macintosh Plus, commonly referred to as “linnunpönttö” (birdhouse) in finnish, is a computer I got to test hands-on way later than it was released. By the time I did, Amiga 500 had been ruling the home computer hobbyist scene for years. Familiar with A500’s awesome capabilities the Plus (with it’s small gray-scale monitor) simply was, in comparison, a uninteresting relic.
Fast forward ten (or so) years and I found myself looking at one in a second hand store. With a near yours-for-free-if-you-take-it-out-the-shop price tag, the Plus powered on nicely but came only with a keyboard (minus one key cap). The lack of OS disks and mouse made it pretty much a unusable piece-of-shit. Nonetheless, I took it with me and stored it away to wait for closer inspection. Then life had its funny ways, and the Plus sat in the basement waiting.. and waiting, right up until this august when I dug it up thinking “maybe it’s about time..” And here, we start to close in on this post.
There is a lot of info about Mac+ out and about the net. But as it often is with these retro systems, not everything is necessarily applicable or usable, or you’ll simply come across a bunch of dead links. One of my ideas with this post was to compact my findings and provide one usable solution for “how to get that damn can of worms up and running“. If you, like me, acquired a second-hand Plus with just a keyboard, this one is a definite read for you. Maybe you’ll have a little less grandiose mission getting your Plus back in action ;)
Recently found a lightly damaged Ensoniq VFX and a VPC-102 cartridge in the dumpster. Surprisingly, it turned out a working one! Yay for that \o/
Whilst repairing the synth, I couldn’t resist the temptation to also tear apart the cart and see how it works: This turned out to use a bog-standard 27C256 EPROM circuit. Less surprisingly, in no time I found myself thinking about a ROM adapter.. Yep, let’s haxx0r!
My cart mod is based on Steve Wahl’s cart conversion, but I wanted to make the ROM chips easily replaceable. So, instead of having the chip on the board I decided to install a ZIF-socket in a 90° angle and have it resting on top of the VFX panel. Additionally, I replaced the two (zero ohm) bridging resistors with DIP-switches to allow using both EPROM and EEPROM chips.