2 layers130 × 156 mm
4 layers96 × 96.3 mm
Mstd
xvrxvr/mstdBoth machines are based on the K1801 series CPUs, which are compatible with the DEC PDP-11 instruction set and use a simplified version of the DEC UNIBUS-like MPI system bus.\ Wiki MPI BUS (In Russian)
- Size
- 96 × 96.3 mm
- Copper layers
- 4
- Thickness
- 1.61 mm
- Parts
- 94
- Nets
- 149
- Pads
- 507
- Tracks, vias
- 1,686, 287
- Pours
- 3
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 7 Jun 2025
- Updated
- 7 Feb 2026
Overview
Mstd is an open-source printed circuit board by xvrxvr, from the xvrxvr/mstd repository on GitHub, published under the MIT licence. It is a 4-layer board of 96 × 96.3 mm with 94 parts on 149 nets, routed with 1,686 tracks and 287 vias.
It is built around the ICE40UP5K-SG48ITR50, ESP32-WROOM-32E-N16 and 74HCT05, with the 74LVX3245MTCX, 74HCT4066D and APX803S-31SA among its other parts. Its parts include 39 resistors, 24 capacitors, 11 ICs, 2 crystals and 1 diode. It belongs with the ESP32 and FPGA and CPLD boards of this library.
Main components
11
ICE40UP5K-SG48ITR50
QFN-48QFN-48 Programmable Logic Device (CPLDs/FPGAs) ROHSLatticeProgrammable Logic Device (CPLDs/FPGAs)
ESP32-WROOM-32E-N16
WIFI-SMD-40℃~+85℃ -98dBm 112mA 2.4GHz 20dBm 239mA 3V~3.6V Bluetooth4.2 ESP32-DOWD-V3 On-board PCB Antenna UART、SDIO、SPI、I2C、GPIO、ADC、DAC、Ethernet、TWAI SMD,25.5x18mm WiFi Modules ROHSEspressif SystemsWiFi Modules74HCT05
--55℃~+125℃ 2 20ns@6V,50pF 2V~6V 2uA 5.2mA 5.2mA 74HCT Series NOR Gate - Logic Gates ROHSonsemiLogic Gates
74LVX3245MTCX
TSSOP-24-40℃~+85℃ 1 2.7V~3.6V 24mA 24mA 4.5V~5.5V 8 Bidirectional Level translator Output enable high-impedance TTL Tri-State TSSOP-24 Translators, Level Shifters ROHSonsemiTranslators, Level Shifters
74HCT4066D
SOIC-14-40℃~+125℃ 15ns 180MHz 1:1 30ns 4.5V~5.5V 44ns 54Ω 8pF SOIC-14 Analog Switches, Multiplexers ROHSNexperiaAnalog Switches, Multiplexers
APX803S-31SA
SOT-23-40℃~+85℃ 1 10uA 1V~5.5V 240ms 3.08V Active Low No No Open Drain Voltage Monitor SOT-23 Supervisor and Reset ICs ROHSDiodes IncorporatedSupervisor And Reset ICs
TLV70212DBVR(MS)
SOT-23-5-40℃~+85℃@(Ta) 1 1.2V 2uA 300mA 450mV@(300mA) 5.5V 80dB@(100Hz) 80uVrms Fixed Over Current Protection、Over Temperature Protection、Enable Positive SOT-23-5 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSMSKSEMIVoltage Regulators - Linear, Low Drop Out (LDO) RegulatorsTMI6050-33
SOT-23-5-40℃~+125℃@(Tj) 1 3.3V 5.5V 600mA 600mV@(600mA) 60dB@(1kHz) 75uA Fixed Over Current Protection、Over Temperature Protection、Enable、Short Circuit Protection Positive SOT-23-5 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSTMIVoltage Regulators - Linear, Low Drop Out (LDO) RegulatorsBAT54C
SOT-231 Pair Common Cathode 200mA 2uA@25V 30V 600mA 800mV@100mA SOT-23 Schottky Diodes ROHSNexperiaSchottky Diodes
TSX101G100-250
插件-6P,10x10mm插件-6P,10x10mm Multi-Directional Switches ROHSBRIGHTMulti-Directional Switches
TYPEC-306DDW-ARP16
弯插-45℃~+85℃ 1 10000 times 16P 5A 8.97mm Black Female Right Angle Type-C USB 3.1 弯插 USB Connectors ROHSXUNPUUSB Connectors
README
README.mdUKNC-BK MSTD+
UKNC-BK MSTD+ is a universal external mass storage device designed to work simultaneously with two Soviet-era 16-bit computers from the 1980s: the Elektronika BK0010/0011 and the Elektronika MS0511 (UKNC).
https://en.wikipedia.org/wiki/Electronika_BK
https://en.wikipedia.org/wiki/UKNC
Both machines are based on the K1801 series CPUs, which are compatible with the DEC PDP-11 instruction set and use a simplified version of the DEC UNIBUS-like MPI system bus.
Wiki MPI BUS (In Russian)
While the physical connectors differ between the two systems (UKNC using an extended version), they are logically compatible.
To accommodate both, the board features two separate bus connectors—one for each computer.
Key Features
- Hardware: Built on an ICE40UP5K FPGA and an ESP32 microcontroller.
- Display: Includes a small OLED screen for disk image selection and device configuration.
- Storage: Does not use SD cards. Disk images are uploaded via Wi-Fi and stored in the device’s internal Flash memory.
- Power: USB-C connector is used only for additional power supply.
- Compatibility: Works with both BK0010/BK0011 and UKNC (MS0511) computers.
Current Status (July 2027)
- Custom PCB designed in KiCad
- Hardware assembly and testing in progress
Additional Resources
📺 Elektronika MS0511 (UKNC) Review
The Clueless Engineer
📚 DEC PDP-11 Instruction Set Reference
Official DEC documentation archive
🖥️ UKNC Emulator
Cross-platform emulator for Elektronika MS0511
Parts
94| Qty | Value | Footprint | References |
|---|---|---|---|
| 20 | 1.0 | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2, C10, C11, C12, C13, C14, C15, C16, C17, C19, C22, C23, C24, C25, C26 +4 |
| 13 | 100K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R14, R15, R16, R18, R19, R23, R24, R27, R28, R32, R35, R36, R37 |
| 9 | 10K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R2, R5, R6, R7, R8, R9, R13, R20, R22 |
| 8 | 1K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R10, R11, R12, R17, R21, R25, R26, R38 |
| 7 | TestPoint | TestPoint:TestPoint_THTPad_D1.0mm_Drill0.5mm | TP1, TP2, TP3, TP4, TP5, TP6, TP7 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3_ISO14580 | H1, H2, H3, H4 |
| 3 | R | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R29, R30, R31 |
| 2 | 10x16V | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C6, C7 |
| 2 | 2K2 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R3, R4 |
| 2 | 5K1 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R40, R41 |
| 2 | 74HCT05 | Package_SO:SO-14_3.9x8.65mm_P1.27mm | U8, U10 |
| 2 | 74LVX3245MTCX | Package_SO:SOP-24_7.5x15.4mm_P1.27mm | U5, U6 |
| 2 | SolderJumper_3_Bridged12 | Jumper:SolderJumper-3_P1.3mm_Bridged12_RoundedPad1.0x1.5mm | JP1, JP2 |
| 1 | 100 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1 |
| 1 | 100x16V | Capacitor_THT:CP_Radial_D6.3mm_P2.50mm | C8 |
| 1 | 200 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R39 |
| 1 | 20x16V | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C5 |
| 1 | 2N7002 | Package_TO_SOT_SMD:SOT-23 | Q2 |
| 1 | 74HCT4066 | Package_SO:SO-14_3.9x8.65mm_P1.27mm | U12 |
| 1 | APX803S-31SA | Package_TO_SOT_SMD:SOT-23-3 | U9 |
| 1 | BAT54C | Package_TO_SOT_SMD:SOT-23 | D4 |
| 1 | ESP32-WROOM-32E-N16 | local:ESP32-WROOM-32E-N8 | U4 |
| 1 | ICE40UP5K-SG48ITR | Package_DFN_QFN:QFN-48-1EP_7x7mm_P0.5mm_EP5.6x5.6mm | U1 |
| 1 | PROG | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J1 |
| 1 | SSD1306 OLED | local:SDD1306-1 | U7 |
| 1 | TLV70212DBVR | easyeda2kicad:SOT-23-5_L3.0-W1.7-P0.95-LS2.8-BL | U2 |
| 1 | TMI6050-33 | easyeda2kicad:SOT-23-5_L2.9-W1.6-P0.95-LS2.8-BR | U3 |
| 1 | TSX101G100-250 | easyeda2kicad:SW-TH_TSX101G100-250 | SW1 |
| 1 | TYPEC-306DDW-ARP16 | easyeda2kicad:USB-C-TH_TYPEC-306DDW-ARP16 | USB1 |
| 1 | ~ | local:09722642801-1 | X3 |
| 1 | ~ | local:snp15 | X4 |
Questions
How big is the Mstd PCB?
It measures 96 × 96.3 mm and has 4 copper layers, 1.61 mm thick.
What parts does the Mstd use?
94 parts, built around the ICE40UP5K-SG48ITR50, ESP32-WROOM-32E-N16, 74HCT05 and 74LVX3245MTCX. 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 Mstd KiCad files?
From the xvrxvr/mstd repository on GitHub, at the commit this page was made from: the board is mstd/mstd.kicad_pcb and its schematic mstd/cpu.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Mstd 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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