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[[Category:Spectrum]] | [[Category:Spectrum]] | ||
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{{Template:Spectrum edge connector|A15|A13|D7|[[#ROM disable pins|{{overline|OE}}]]|[[# | {{Template:Spectrum edge connector|A15|A13|D7|[[#ROM disable pins|{{overline|OE}}]]|[[#Key Slot|SLOT]]|D0|D1|D2|D6|D5|D3|D4|{{overline|INT}}|{{overline|NMI}}|{{overline|HALT}}|{{overline|MREQ}}|{{overline|IORQ}}|{{overline|RD}}|{{overline|WR}}|[[#Power|NC]]|{{overline|WAIT}}|[[#Power|+12{{small|V}}]]|[[#Power|−12{{small|V}}]]|{{overline|M1}}|{{overline|RFS}}|A8|A10|[[#RESET|RESET]]|A14|A12|[[#Power|+5{{small|V}}]]|[[#Power|NC]]|[[#Key Slot|SLOT]]|0{{small|V}}|0{{small|V}}|[[#CPU Clock|CKEXT]]|A0|A1|A2|A3|NC|0{{small|V}}|[[#ROM disable pins|{{overline|OE}}]]|{{overline|[[#Disc Controller Signals|DRD]]}}|{{overline|[[#Disc Controller Signals|DWR]]}}|{{overline|[[#Disc Controller Signals|MTR]]}}|{{overline|BUSRQ}}|{{overline|RESET}}|A7|A6|A5|A4|[[#ROM disable pins|NC]]|{{overline|BUSACK}}|A9|A11}} | ||
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====Disc Controller Signals==== | ====Disc Controller Signals==== | ||
Unlike the +3, the +2A and +2B have no floppy disc controller. Amstrad's original intention was to produce an external floppy controller addon which would have connected to the expansion port on these computers. Since the [[The Amstrad ASIC|ASIC]] is the same on all three machines, all the decoding logic is already present to generate the disk read/write and motor control signals. These three signals are therefore connected through to the expansion port. | Unlike the +3, the +2A and +2B have no floppy disc controller. Amstrad's original intention was to produce an external floppy controller addon which would have connected to the expansion port on these computers. Since the [[The Amstrad ASIC|ASIC]] is the same on all three machines, all the decoding logic is already present to generate the disk read/write and motor control signals. These three signals are therefore connected through to the expansion port. | ||
These signals occupy the pins which were originally used for the component video signals on the [[ | These signals occupy the pins which were originally used for the component video signals on the [[ZX Spectrum 16k/48k Edge Connector|16k/48k]] expansion port. | ||
====RESET==== | ====RESET==== | ||
The RESET signal is an inverted version of the {{overline|RESET}} signal, and is produced by one of the inverters in IC15. The purpose of this signal is unclear since any peripheral could derive it by inverting the {{overline|RESET}} line itself. In the +3 it is connected via a 10k resistor (R76) to the floppy drive select line. This however seems to be an error in the circuit design though it has no adverse effects. | The RESET signal is an inverted version of the {{overline|RESET}} signal, and is produced by one of the inverters in IC15. The purpose of this signal is unclear since any peripheral could derive it by inverting the {{overline|RESET}} line itself. In the +3 it is connected via a 10k resistor (R76) to the floppy drive select line. This however seems to be an error in the circuit design though it has no adverse effects. |