4 layers100 × 100 mm
Design files
ashlin4010/simple_Z80_computer
Minimally complex Z80 computer while still being usable
48 partsMIT
4 layers100 × 100 mm
CompactFlash
ashlin4010/simple_Z80_computerMinimally complex Z80 computer while still being usable
- Size
- 100 × 100 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 49
- Nets
- 117
- Pads
- 282
- Tracks, vias
- 312, 19
- Pours
- 5
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 15 Dec 2023
- Updated
- 3 Jun 2024
Overview
CompactFlash is an open-source printed circuit board by ashlin4010, from the ashlin4010/simple_Z80_computer repository on GitHub, published under the MIT licence. It is a 4-layer board of 100 × 100 mm with 49 parts on 117 nets, routed with 312 tracks and 19 vias.
It is built around the CH340N. Its parts include 20 resistors, 9 diodes, 9 connectors, 3 ICs and 2 capacitors. It belongs with the Raspberry Pi (Linux) boards of this library.
Main components
1README
README.mdSimple Z80 Computer
The goal of this project was to build a minimally complex Z80 computer capable of running CP/M. While I haven not yet ported CP/M, it should be capable of it.
This system is made of two boards, the upper board has the the CPU, RAM, ROM and UART. The lower board has Composite Video, USB Keyboard, USB to serial converter, Compact Flash and 8 indicator LEDs.
If you want to have a better understanding of how this system works you checkout the schematics or my blog.
Specifications
- 64K Static RAM
- 32K ROM
- Z80 @ 4Mhz
- USB Keyboard via Raspberry Pi Zero
- Composite Video via Raspberry Pi Zero
- HDMI Video via Raspberry Pi Zero
- Support for 27256 or AT28C256 ROM
- Compact Flash
- 8 LED indicators
- Built-in USB to serial converter @ 9600 baud
Raspberry Pi Zero (Optional)
As part of the project I wanted to have a composite video output however, there was not sufficient space to have a native composite video interface. As an alternative I have used a Raspberry Pi Zero running pigfx which acts as a terminal emulator providing a USB keyboard input and composite video output.
Raspberry Pi Installation
To the underside of the PCB solder in the Raspberry Pi using the pins from a 2.54mm header so that the Pi is flat against the PCB. Only the circles and yellow need to be soldered. Back on the top side of the PCB you will see some pads that need to be connected to some test points on the Pi, connect them using some wire cuts offs.
ROM Jumper Configuration
This system supports the W27C257, 27256 and AT28C256 ROM chips. The W27C257 and 27256 are read-only and need to have jumpers set in the topmost position. The AT28C256 is read/write and needs two jumpers in the lower position.
Software Compiler
My assembler of choice for this project has been the Retro Assembler by Peter Tihanyi. There is a VSCode plugin available.
Serial Bootloader
The early version of the monitor includes a utility "sboot" that will fetch data over the UART and store it in the lower 32k and jump to the start of memory.
For the serial bootloader to work you must be running the server utility that will provide the files for sboot to load. You can find it in software/server.
The sboot command can be configured to auto start on boot by setting UART_AUTO_BOOT to True in monitor.z80.asm and re-building.
Memory Address Space
This system has 64K of RAM and 32K of ROM. However, the Z80 can only ever address 64K at a time. When the system starts up the top 32K of memory maps to RAM, and the lower 32K maps to ROM. The system can, when ready, swap the lower 32K of ROM for RAM.
IO Address Space
| Address | Device | R/W | Description |
|---|---|---|---|
| 0x10 | SIO | R/W | UART A Data Register |
| 0x11 | SIO | R | UART A Status Register |
| 0x12 | SIO | R/W | UART B Data Register |
| 0x13 | SIO | R | UART B Status Register |
| 0x20 | 8-bit Latch | W | LED Output |
| 0x30-37 | Compact Flash | R/W | Compact Flash Registers |
| 0x70 | Flip-flop | W | RAM/ROM Page |
Schematics
Z80 Main Board Schematics - PDF
Compact Flash & Raspberry Pi Board - PDF
BOM
Z80 Board
| Id | Designator | Footprint | Quantity | Designation | Supplier and ref | ||
|---|---|---|---|---|---|---|---|
| 1 | J2 | PinHeader_1x04_P2.54mm_Vertical | 1 | Conn_01x04_Male | |||
| 2 | C3,C2,C4,C5,C17,C12,C14,C6,C7,C16,C9,C13,C8,C10,C11,C15 | C_Disc_D3.0mm_W1.6mm_P2.50mm | 16 | 0.1uf | https://www.digikey.co.nz/en/products/detail/kemet/C320C104K5R5TA7303/3726160 | ||
| 3 | R2,R1,R3,R4 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | 4 | 2k7 | |||
| 4 | R5 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | 1 | 1k | |||
| 5 | C1 | C_Disc_D3.0mm_W1.6mm_P2.50mm | 1 | 150pF | https://www.digikey.co.nz/en/products/detail/vishay-beyschlag-draloric-bc-components/K151J15C0GF5TL2/286469 | ||
| 6 | U1 | DIP-40_W15.24mm_Socket | 1 | Z80CPU | |||
| 7 | U7 | DIP-40_W15.24mm | 1 | Z8440 | |||
| 8 | U14, U2 | DIP-28_W15.24mm | 1 | KM62256CLP | |||
| 9 | U13 | DIP-20_W7.62mm_Socket | 1 | 74LS374 | |||
| 10 | U5 | DIP-14_W7.62mm_Socket | 1 | 74LS04 | |||
| 11 | U9 | DIP-16_W7.62mm_Socket | 1 | 74LS161 | |||
| 12 | U3 | DIP_Socket-28_W11.9_W12.7_W15.24_W17.78_W18.5_3M_228-1277-00-0602J | 1 | 27256 | |||
| 13 | X1 | Oscillator_DIP-8 | 1 | CXO_DIP8 | https://www.digikey.co.nz/en/products/detail/abracon-llc/ACH-8-000MHZ-EK/675379 | ||
| 14 | U15 | TO-92 | 1 | DS1233 | https://www.digikey.co.nz/en/products/detail/analog-devices-inc-maxim-integrated/DS1233-5-T-R/1017808 | ||
| 15 | D2 | LED_D3.0mm | 1 | LED | |||
| 16 | U11,U8 | DIP-14_W7.62mm_Socket | 2 | 74LS74 | |||
| 17 | SW2 | SW_THT_SK-12F17-G_7-0 | 1 | SW_SPDT | https://www.digikey.co.nz/en/products/detail/c-k/SK-12F17-G-7/2747163 | ||
| 18 | U4 | DIP-14_W7.62mm_Socket | 1 | 74LS00 | |||
| 19 | SW1 | SW_PUSH_6mm_H4.3mm | 1 | SW_Push | https://www.digikey.co.nz/en/products/detail/cui-devices/TS02-66-70-BK-160-LCR-D/15634243 | ||
| 20 | U6 | DIP-16_W7.62mm_Socket | 1 | 74LS138 | |||
| 21 | J1 | PinSocket_2x16_P2.54mm_Vertical | 1 | Conn_01x32_Pin | |||
| 22 | J4 | BarrelJack_CUI_PJ-037A | 1 | Jack-DC | https://www.digikey.co.nz/en/products/detail/cui-devices/PJ-037A/1644545 | ||
| 23 | U12 | DIP-14_W7.62mm_Socket | 1 | 74LS32 | |||
| 24 | J7 | PinSocket_2x06_P2.54mm_Vertical | 1 | Conn_01x12_Male | |||
| 25 | J3 | PinHeader_2x03_P2.54mm_Vertical | 1 | Conn_02x03_Odd_Even |
CompactFlash
| Id | Designator | Footprint | Quantity | Designation | Supplier and ref | ||
|---|---|---|---|---|---|---|---|
| 1 | R2 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | 1 | 100R | |||
| 2 | J2 | PinHeader_2x06_P2.54mm_Vertical | 1 | Conn_01x12_Male | |||
| 3 | J7,J8 | SolderWirePad_1x01_SMD_1x2mm | 2 | Conn_01x01_Pin | |||
| 4 | R8,R9,R7,R10 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | 4 | 10k | |||
| 5 | J5 | SWITCHCRAFT_PJRAN1X1U04X | 1 | RCA_Video | https://www.digikey.co.nz/en/products/detail/switchcraft-inc/PJRAN1X1U04X/969899 | ||
| 6 | U1 | CF-Card_101D-TAAB-R01 | 1 | Compact_Flash | https://www.digikey.co.nz/en/products/detail/attend-technology/101D-TAAB-R01/17633884 | ||
| 7 | U2 | DIP-20_W7.62mm | 1 | 74LS541 | |||
| 8 | Q2,Q1 | TO-92_Inline | 2 | 2N7000 | https://www.digikey.co.nz/en/products/detail/diotec-semiconductor/2N7000/13164314 | ||
| 9 | D2,D8,D6,D1,D4,D7,D5,D9,D3 | LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | 9 | LED | |||
| 10 | R1,R5,R6,R3,R4 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | 5 | 1K | |||
| 11 | U3 | SOP-8_3.9x4.9mm_P1.27mm | 1 | CH340N | https://vi.aliexpress.com/item/1005004980156804.html | ||
| 12 | R19,R20 | R_0805_2012Metric | 2 | 1k | https://www.digikey.co.nz/en/products/detail/stackpole-electronics-inc/RNCP0805FTD1K00/2240229 | ||
| 13 | R14,R15,R18,R11,R13,R16,R17,R12 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | 8 | 1k | |||
| 14 | J1 | Raspberry_Pi_Zero_Socketed_THT_FaceDown_MountingHoles | 1 | Raspberry_Pi_Zero | |||
| 15 | J4 | PinSocket_2x16_P2.54mm_Vertical | 1 | Conn_01x32_Pin | |||
| 16 | J6 | USB_Mini-B_Wuerth_65100516121_Horizontal | 1 | USB_B_Micro | https://www.digikey.co.nz/en/products/detail/amphenol-cs-commercial-products/GMSB0532112YEU/13683104 | ||
| 17 | J3 | 629104190121 | 1 | USB_A | https://www.digikey.co.nz/en/products/detail/w%C3%BCrth-elektronik/629104190121/6644275 | ||
| 18 | J10 | PinSocket_1x04_P2.54mm_Vertical | 1 | Conn_01x04_Pin | |||
| 19 | C1 | C_Disc_D3.0mm_W1.6mm_P2.50mm | 1 | 100pF | |||
| 20 | C2 | C_0805_2012Metric | 1 | 100nF | https://www.digikey.co.nz/en/products/detail/samsung-electro-mechanics/CL21B104KBCNNNC/3886661 |
Parts
49| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 1k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R11, R12, R13, R14, R15, R16, R17, R18 |
| 5 | 1K | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R1, R3, R4, R5, R6 |
| 4 | 10k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R7, R8, R9, R10 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3, H4 |
| 2 | 1k | Resistor_SMD:R_0805_2012Metric | R19, R20 |
| 2 | 2N7000 | Package_TO_SOT_THT:TO-92_Inline | Q1, Q2 |
| 2 | Conn_01x01_Pin | Connector_Wire:SolderWirePad_1x01_SMD_1x2mm | J7, J8 |
| 1 | 100R | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R2 |
| 1 | 100nF | Capacitor_SMD:C_0805_2012Metric | C2 |
| 1 | 100pF | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C1 |
| 1 | 74LS541 | Package_DIP:DIP-20_W7.62mm | U2 |
| 1 | CH340N | Package_SO:SOP-8_3.9x4.9mm_P1.27mm | U3 |
| 1 | Compact_Flash | Z80:CF-Card_101D-TAAB-R01 | U1 |
| 1 | Conn_01x04_Pin | Connector_PinSocket_2.54mm:PinSocket_1x04_P2.54mm_Vertical | J10 |
| 1 | Conn_01x12_Male | Connector_PinHeader_2.54mm:PinHeader_2x06_P2.54mm_Vertical | J2 |
| 1 | Conn_01x32_Pin | Connector_PinSocket_2.54mm:PinSocket_2x16_P2.54mm_Vertical | J4 |
| 1 | D0 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D2 |
| 1 | D1 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D3 |
| 1 | D2 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D4 |
| 1 | D3 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D5 |
| 1 | D4 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D6 |
| 1 | D5 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D7 |
| 1 | D6 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D8 |
| 1 | D7 | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D9 |
| 1 | LED | LED_THT:LED_D3.0mm_Horizontal_O1.27mm_Z2.0mm | D1 |
| 1 | RCA_Video | Z80:SWITCHCRAFT_PJRAN1X1U04X | J5 |
| 1 | Raspberry_Pi_Zero | Z80:Raspberry_Pi_Zero_Socketed_THT_FaceDown_MountingHoles | J1 |
| 1 | USB_A | Z80:629104190121 | J3 |
| 1 | USB_B_Micro | Connector_USB:USB_Mini-B_Wuerth_65100516121_Horizontal | J6 |
Questions
How big is the CompactFlash PCB?
It measures 100 × 100 mm and has 4 copper layers, 1.6 mm thick.
What parts does the CompactFlash use?
49 parts, built around the CH340N. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the CompactFlash KiCad files?
From the ashlin4010/simple_Z80_computer repository on GitHub, at the commit this page was made from: the board is design_files/CompactFlash/CompactFlash.kicad_pcb and its schematic design_files/CompactFlash/CompactFlash.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the CompactFlash design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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