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Images on tap

Xav finally presents that Team Tap circuit diagram...

** TEAMTAP.JPG smallish here **

** TEAMTAP.GEM here - across two, maybe three columns **
** ON READER DISK logo here **
** caption **
Idealised circuit diagram of Atari's Team Tap. This image has also been included on the Reader Disk in GEM metafile format
** /caption **

The circuit diagram isn't nearly as daunting as it first appears - although that's mostly because I spent ages laying it out neatly! The actual circuit board looks far more complex.

Technical notes

All the diodes are small signal diodes, 1N1418 or similar and cost a few pence each - they're the same as the ones used in the joypad, and several forthcoming EJP projects, so it might be worth buying them in bulk (Maplins often sell bundles of 100 for a few pounds). The capacitors C1 and C1 are both ceramic disk types which act as local reservoirs of energy for the ICs, so should be mounted as close to U1 and U2 as possible.

If you're wondering about that, apparently out of place, diode connected to pin 3 on port D (and hence to pin 11 of U1) join the club! I'm not certain of its purpose either. Nevertheless, I have checked and double checked an original Team Tap, and it's definitely present on the circuit board.

A similar anomaly is the connection between pins 7 and 8 of each of the four joypad sockets. All logic dictates these should connect to the positive supply, but detailed examination of the original Team Tap shows this is not the case.

Before the next issue I intend to construct my own Team Tap so I should be able to report more on these oddities as my experiments progress. Naturally errors may have crept into my initial examination of the Team Tap - or the subsequent conversion of back-of-envelope designs to the circuit diagram presented here.

Neither myself nor Atari Computing accept any responsibility for anything based on this design.

Next time we'll begin breaking this diagram down into manageable sections. In the meantime it's worthwhile re-reading the previous columns which should help you figure out at least some of the technical details and you might also notice some similarity with the joypad diagram itself.