Internet  Pinball Database

Spirit of 76's entry in the IPD

Flyer

Front - Back

Manual (scanned by yours truly)

Schematic

ROM images

n/a

WAV files

-

Rule sheet

Repair tips

S/I card scans

Repro parts

Mirco's Spirit of '76 holds a significant place in pinball history as being the first microcomputer-controlled pinball machine.  Previously, pinball machines were packed with relays, score reels, and other electromechanical components, all of which were to be rendered obsolete by solid-state electronics. 

Unfortunately, this was Mirco's first attempt at designing and manufacturing a pinball machine and while the machine was an electronic breakthrough, it was a marketing failure.  It was (and still is) criticized for its ugly graphics and unexciting game play.  This may help explain why only 127 machines were built, and why Mirco faded quickly into obscurity.  But within another few years, every game manufacturer switched over from relays to microprocessors and never looked back.  Maybe the world just  wasn't ready for a pinball machine made in Phoenix, Arizona.

I think the game may have done better if there had been more action on the playfield.  As it is, there are a pair of slingshots (a pinball must-have), and three ordinary pop bumpers which are arranged in a pattern that precludes much ball action among them.  Other than that, there is nothing else for the pinball to do other than bounce off dead rubbers or hit static targets for scoring.  Mirco had no prior experience designing a pinball machine, and they chose to design a machine without drop targets, kick-out holes, multi-ball or other goodies that were commonly seen in the other electromechanical machines of the day.  Maybe they didn't have the budget, design skills or foresight to incorporate some of these things to make the game more appealing.  The company was probably undercapitalized, and it had to set up distribution around the many restrictions imposed by the established Chicago-based manufacturers.  Sure, the game is ugly and boring, but Mirco had even greater impediments to its success; a success it unfortunately never achieved.

I was able to get this game in complete but nonworking condition.  Fortunately, it also came with a couple of boxes of spare parts and a spare playfield.  I was also able to find a service manual which unfortunately does not have schematics.  I scanned the manual and it is accessible from the Resources section above. 

The CPU appears to be a Motorola 6800, with a single 6820 used for I/O.  The program memory seems to be stored in ten 512 x 4 bit bipolar PROMs  That's no more than 2 ½ Kbytes of program memory.  RAM is a whopping 256 bytes, using two 2112 static RAMs.  The CPU, score LED's,  backbox displays, and lamp and solenoid drivers are all contained on the main board.  The cabinet contains the power supply, and EM-style chime unit, and a mystery.

The mystery is about the sound.  Page 21 of the manual shows a "special sound effects board", and the flyer makes reference to electronic sound effects.  However, in all the games that I have seen (um, two), there is no sign of this board, or any wiring for it.  The mystery is, did this sound module ever made it into production?

First things for me to do with this game is to archive the program PROMs and then do a little reverse-engineering to help with troubleshooting.  The cosmetics of the game I have are very good, so with a little luck, this ugly duckling will live again.