sinclair ZX-edge-connector
This is a synopsis-like diagramm of the edge-connectors of the ZX81 (ZX80
and jupiter ace are the same as I know), the standard-spectrum and the
Amstrad +2A. It s may be usefull for those interested in connecting
peripherals to versions of ZX-computers they are not originaly designed
for. And for those not having a edge-connector-diagram of their own
computer, of course. The main column is that of the original good old
Spectrum. The others are given if they are different to the Spectrum. In
the original diagram for the +2A from Amstrad the slot is not counted. It
seems to me less usefull, because it is at all the other ZX-computers!
Remember that at some series not all the lines connected to the edge
connector, especially the video-signals fbas, /y, v or u! Mostly there is
just a piece of wire needed to connected the right two holes of the PCB.
component-side B number under-side A
+2A spectrum 81 specci 81 81 spectrum +2A
+2A
A15 1 A14
A13 2 A12
D7 3 1 +5V
/ROM1OE nc /RAMCS 4 2 Uss nc
SLOT 5 3 SLOT
D0 6 4 GND
D1 7 5 GND
D2 8 6 /CLK
D6 9 7 A0
D5 10 8 A1
D3 11 9 A2
D4 12 10 A3
/INT 13 11 A15 /IOULA nc
/NMI 14 12 A14 GND
/HALT 15 13 A13 FBAS /ROM2OE
/MREQ 16 14 A12 /Y DISKRD
/IORQ 17 15 A11 V DISKWR
/RD 18 16 A10 U MOTORON
/WR 19 17 A9 /BUSREQ
-5V /BUSACK 20 18 A8 /RESET
/WAIT 21 19 A7
+12V BUSREQ 22 20 A6
-12V U~ /RESET 23 21 A5
/M1 24 22 A4
/RFSH 25 23 /ROMCS nc
A8 26 /BUSACK
A10 27 A9
/RESET nc 28 A11
Uss is the power directly from the power socket
U~ is the AC from the switching regulator
(the chirping coil), the so called -12V
FBAS is the complete color-video-signal
/Y is the inverted B/W including sync (BAS)
U and V are the color-difference-signals including PAL-coding
/IOULA is IO-port254-signal for the ULA
/ROM1OE and /ROM2OE may be ORed to /ROMCS (so-called "Fixer")
DISKRD, DISKWR, MOTOR ON have something to do with the +3-upgrade
(somebody knowing more about it???)