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Zx50 Bus Probe RevB

mmosko·Zx50·boards/Zx50_Bus_Probe_RevB/Zx50 Bus Probe_RevB.kicad_pcb

Zx50 Bus Probe RevB PCB layout, top view — open source RP2040/RP2350 board by mmosko

About the Zx50 Bus Probe RevB PCB

Zx50 Bus Probe RevB is an open source RP2040/RP2350 PCB design by mmosko, published on GitHub. It is a 4-layer board measuring 145.9 × 147.3 mm, with 80 components from 43 distinct parts.

Its main chip is the RaspberryPi_Pico, from the RP2040/RP2350 family. Other key parts include the MCP23S17_SP, CD74HC4051E, SN74ABT245BN, CD74HC154M96 and OPA356XXD. By type, the board carries 25 capacitors, 23 ICs, 17 connectors, 10 resistors, 3 diodes and 1 module.

From the project

The Zx50 is a custom 8-slot, passive backplane Z80 computer. It uses a "Shadow Bus" architecture where a Raspberry Pi Pico can take over the bus via DMA (~BUSRQ / ~BUSAK) to load RAM, debug, and monitor the system.

The Zx50 is a custom 8-slot, passive backplane Z80 computer. It uses a "Shadow Bus" architecture where a Raspberry Pi Pico can take over the bus via DMA (~BUSRQ / ~BUSAK) to load RAM, debug, and monitor the system.

* Backplane: 8 slots. Fully terminated with 10K SIP pull-up resistors on Address, Data, and Control lines. Includes an ~IEI/~IEO interrupt daisy chain and heavy bulk capacitance (1000µF).

Main components on the Zx50 Bus Probe RevB

MCP23S17_SPCD74HC4051ESN74ABT245BNCD74HC154M96OPA356XXDPIC18F4620-I_P74AHCT541PIC18F27Q43-I/SOMCP23S17_SORaspberryPi_Pico

Zx50 Bus Probe RevB bill of materials (BOM)

80 components, 43 distinct parts — part numbers from the project's BOM.

QtyPartRefs
2
MCP23S17_SP
MCP23S17_SO
U1, U13
9
CD74HC4051E
74CBT3251
U2, U3, U4, U5, U8, U9, U10, U11 +1
2
SN74ABT245BN
U6, U7
1
CD74HC154M96
U14
2
OPA356XXD
OPA356xxD
U15, U16
1
PIC18F4620-I_P
SN74ABT245BN
U17
1
74AHCT541
U18
3
SN74ABT245BN
U19, U22, U23
1
PIC18F27Q43-I/SO
U20
1
MCP23S17_SO
U21
1
RaspberryPi_Pico
A1
1
ZX50_EDGECONNECTOR
Zx50_EdgeConnector
J1
1
OUT
J2
1
IN
J3
1
PIC PGM
J4
1
P0
J5
1
P1
J6
1
P2
J7
1
Send/Recv Card
J8
1
CH0
J9
Show 23 more
QtyPartRefs
1
CH1
J10
1
CH2
J11
1
CH3
J12
1
Z80_ADDR
Z80_Addr
J15
1
Z80_DATA
Z80_Data
J16
1
Z80_CTRL
Z80_Ctrl
J17
1
SH_Data
J19
1
SH_Ctrl
J20
1
EA 205G-4NLED
LCD1
1
PWR
D3
1
1N4001
D4
1
PIC
D5
24
.1uF
C1, C2, C3, C4, C5, C6, C7, C8 +16
1
10UF
47uF
C21
1
49.9R 1W 1%
R1
1
49.9R 1W 1%
R2
2
10K
R3, R4
1
2.2K
2.2k
R5
1
3.3K
3.3k
R6
1
470
R9
1
33R
R10
1
470
R11
1
3.3K
R20

Zx50 Bus Probe RevB design files

The KiCad project lives in the mmosko/Zx50 repository on GitHub; these links point at the commit this page was built from.

Zx50 Bus Probe RevB: common questions

What microcontroller does the Zx50 Bus Probe RevB use?

The Zx50 Bus Probe RevB is built around the RaspberryPi_Pico, from the RP2040/RP2350 family.

How big is the Zx50 Bus Probe RevB PCB?

The Zx50 Bus Probe RevB measures 145.9 × 147.3 mm, has 4 copper layers and is 1.6 mm thick.

How many components are on the Zx50 Bus Probe RevB?

80 components, from 43 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the Zx50 Bus Probe RevB design files?

From the mmosko/Zx50 repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the Zx50 Bus Probe RevB design in my own project?

The repository has no license, so all rights stay with mmosko. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the Zx50 Bus Probe RevB without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug RP2040/RP2350 firmware against it before you order a PCB.

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