ZX Spectrum +2A/2B, +3/3B edge connector: Difference between revisions
Jump to navigation
Jump to search
(Convert more instances of 0v to uppercase and use smallcaps for voltages in table) |
(Use overlines for active low signals, fix typo) |
||
Line 3: | Line 3: | ||
[[Category:Spectrum]] | [[Category:Spectrum]] | ||
<!-- end of category list --> | <!-- end of category list --> | ||
{{Template:Spectrum edge connector|A15|A13|D7|[[#ROM disable pins| | {{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{{smallcaps|V}}]]|[[#Power|−12{{smallcaps|V}}]]|{{overline|M1}}|{{overline|RFS}}|A8|A10|[[#RESET|RESET]]|A14|A12|[[#Power|+5{{smallcaps|V}}]]|[[#Power|NC]]|[[#Key_Slot|SLOT]]|0{{smallcaps|V}}|0{{smallcaps|V}}|[[#CPU_Clock|CKEXT]]|A0|A1|A2|A3|NC|0{{smallcaps|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}} | ||
<!-- edge connector table ends --> | <!-- edge connector table ends --> | ||
Line 21: | Line 21: | ||
====ROM disable pins==== | ====ROM disable pins==== | ||
All the previous models of ZX Spectrum have a single ROM chip which could be disabled to facilitate paging in external memory by pulling the | All the previous models of ZX Spectrum have a single ROM chip which could be disabled to facilitate paging in external memory by pulling the {{overline|ROMCS}} line high. The +2A/+3 and +3B however have two ROM chips and brings them out to independent pins on the expansion port. The old {{overline|ROMCS}} pin (Lower pin 25) is not used, and instead Upper pin 4 and Lower pin 15 are used. These pins were both unused on the [[ZX Spectrum 128K Edge Connector|128k+]], however Lower pin 15 was used for composite video out on the [[ZX Spectrum 16k/48k Edge Connector|16k/48k]]. | ||
====Disc Controller Signals==== | ====Disc Controller Signals==== | ||
Line 28: | Line 28: | ||
====RESET==== | ====RESET==== | ||
The RESET signal is an inverted version of the | The RESET signal is an inverted version of the {{overline|RST}} 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|RST}} 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. |