It is a standard 2.54mm double sided 48 pins male connector for expansion. It presents all the Z80 bus signals. On the issue 4 version, the flap has been sealed because expansion insertion may result in a crash due to static electricity. Cambridge Computer decided that it was to too dangerous to leave it open for prying eyes - too many faulty Z88's returned!
Component P C B
Side A Edge Side B
GND 1 SNSL see below
A11 2 +12v
A12 3 A10
A13 4 A9
A14 5 A8
A15 6 A7
clock 7 A6
D4 8 A5
D3 9 A4
D5 10 A3
D6 11 A2
VCC 12 A1
D2 13 A0
GND 14 GND
D0 15 D7
D1 16 M1L
INTL 17 FLP (flap switch)
slot 18 slot
HALTL 19 NMIL
MREQL 20 WRL
IORQL 21 RDL
MAWL 22 RESETL Resets Z88 (2 pulses required)
-BT 23 SVCC 5.4v while the machine is 'on.'
GND 24 SNSL
SNSL allows the machine to be automaticly placed into comotose state buy causing a 'power fail interupt' when an edge connector is plugged into to the expansion slot of the Z88.