CPU board and CPUBUS specs UPDATE

The signals BUSACK, BUSREQ, HALT, NMI, RFSH and WAIT are optional on the CPUBUS, so these pins can be used as user-defined.

The CLK signal is pulled high to ensure the right voltage for the CPU in NMOS/TTL and mixed systems (CMOS CPU and NMOS CRTC for example).

reZet80 CPU bus:
CPUB01: D7
CPUB02: D6
CPUB03: D5
CPUB04: D4
CPUB05: D3
CPUB06: D2
CPUB07: D1
CPUB08: D0
CPUB09: IOREQ
CPUB10: MREQ
CPUB11: NMI | user-defined
CPUB12: INT
CPUB13: RD
CPUB14: WR
CPUB15: BUSACK | user-defined
CPUB16: WAIT | user-defined
CPUB17: BUSREQ | user-defined
CPUB18: RESET
CPUB19: M1
CPUB20: RFSH | user-defined
CPUB21: GND
CPUB22: +5V
CPUB23: A0
CPUB24: A1
CPUB25: A2
CPUB26: A3
CPUB27: A4
CPUB28: A5
CPUB29: A6
CPUB30: A7
CPUB31: A8
CPUB32: A9
CPUB33: A10
CPUB34: A11
CPUB35: A12
CPUB36: A13
CPUB37: A14
CPUB38: A15
CPUB39: CLK
CPUB40: HALT | user-defined