TOP LAYER
BOTTOM LAYER
COMPONENTS:
R2 = any value in range 0-470 Ohm (pull-up resistor for disable external MREQ
signal)
R3-R10 = 100-150 Ohm (resistors for connect data bus = data protector)
R11-R13 = 0 Ohm (for connect signals INT,NMI,HALT)
R14 = 0 Ohm (for connect MREQ signal)
R15 = 0 Ohm (connect signal ROMCS)
R1,R16 = 0 Ohm (for connect ROMOE1 and ROMOE2 signals)
R17 = 0 Ohm (for connect +9V)
D1, D2 = diodes for make signals ROM1OE and ROM2OE from original ROMCS
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BRD for Eagle
, PHOTOS
UNIVERSAL CONFIGURATION FOR ALL 128kB MODELS
Unusable on ZX16/48kB , usable on ZX128/+2/+2A/+3
(R2 unused)
This version protect data bus and convert ROMCS line to ROMOE1/2 lines. Can be
used as universal data protector and "+3 fixed" = enable connect ZX
devices to +2A/+3 models.
UNIVERSAL CONFIGURATION FOR ZX16/48/128/+2
Unusable on +2A/+3 models, usable on ZX16/48/128/+2
(R2, D1, D2 unused = design for all ZX models with one ROMCS signal)
This version use only one ROMCS signals and protect data bus.
CONFIGURATION FOR DISABLE EXTERNAL MEMORY ACCESS
Usable on all ZX models
(R1 , R14, R15, R16, D1, D2 unused = ignore external ROM1OE,ROM2OE,ROMCS signals
and set MREQ for external devices to log.1)
This version disable all external memory and all external devices are useble
only as ports. Protect data bus. Ideal for connect DIVIDE interface on +3e
models (with +3e rom)
ZX BUS PROTECTOR (version 2) is identical
with previous version, only use better PCB design for possibility connect ZX
devices
with plastic case (on +2A/+3 is small space between power connector and ZX bus)
( pin +9V on ZX+2A/+3 is unused in this version)
All SMD components are identical with previous version, only resistor R17 is not used.
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BRD for Eagle
ZX BUS PROTECTOR (version 5) is identical
with previous version, only use better PCB design for possibility connect ZX
devices
with plastic case (on +2A/+3 is small space between power connector and ZX bus)
and new jumper for connect +12V on pin +9V(for +2A/+3 only)
All SMD components are identical with previous version 2, only one additional jumper is used..
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BRD for Eagle
