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|A12||2||2||A13 | |A12||2||2||A13 | ||
|- | |- | ||
| +5v||3||3||D7 | |[[#Power|+5v]]||3||3||D7 | ||
|- | |- | ||
| +9v||4||4||NC | |[[#Power|+9v]]||4||4||NC | ||
|- | |- | ||
|[[#Key_Slot|SLOT]]||5||5||[[#Key_Slot|SLOT]] | |[[#Key_Slot|SLOT]]||5||5||[[#Key_Slot|SLOT]] | ||
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|!BUSRQ||19||19||!WR | |!BUSRQ||19||19||!WR | ||
|- | |- | ||
|!RESET||20||20|| -5v | |!RESET||20||20||[[#Power|-5v]] | ||
|- | |- | ||
|A7||21||21||!WAIT | |A7||21||21||!WAIT | ||
|- | |- | ||
|A6||22||22|| +12v | |A6||22||22||[[#Power|+12v]] | ||
|- | |- | ||
|A5||23||23|| | |A5||23||23||[[#Power|12v AC]] | ||
|- | |- | ||
|A4||24||24||!M1 | |A4||24||24||!M1 | ||
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====Key Slot==== | ====Key Slot==== | ||
The key slot ensures correct alignment of a peripheral with the edge connector. The slot occupies the pin 5 positions | The key slot ensures correct alignment of a peripheral with the edge connector. The slot occupies the pin 5 positions | ||
====Power==== | |||
* Lower Pin 4 is connected to the +9 volt (nominal) DC supply from the ZX Spectrum PSU. | |||
* Lower Pin 3 is connected to the smoothed +5 volt DC output of the internal 7805 regulator. | |||
* Upper Pin 20 is connected to the -5 volt DC output of the internal power supply circuitry. | |||
* Upper Pin 22 is connected to the +12 volt DC output of the internal power supply circuitry. | |||
* Upper Pin 23 is connected to the oscillating voltage within the internal power supply circuitry. This is nominally 12 volts AC. | |||
* Lower Pins 6, 7, and 14 are connected to the 0 volt rail. | |||
====Video Outputs==== | ====Video Outputs==== | ||
Pin 15 on the lower side of the edge connector provides the same composite video signal that is fed into the UHF modulator. | Pin 15 on the lower side of the edge connector provides the same composite video signal that is fed into the UHF modulator. | ||
Lower pin 16 on the carries an inverted luminosity signal to use with the 'U' and 'V' colour difference signals provided on lower pins 18 and 17 respectively | Lower pin 16 on the carries an inverted luminosity signal to use with the 'U' and 'V' colour difference signals provided on lower pins 18 and 17 respectively |