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???)