

Led board
A small 8086 computer system.
- Size
- 99.8 × 100.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 121
- Nets
- 171
- Pads
- 438
- Tracks, vias
- 1,114, 168
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 2 Sep 2020
- Updated
- 14 Jul 2023
Overview
Led board is an open-source printed circuit board by svpetry, from the svpetry/Mini8086 repository on GitHub. It is a 2-layer board of 99.8 × 100.8 mm with 121 parts on 171 nets, routed with 1,114 tracks and 168 vias.
It is built around the A13, 74HC245D and D12, with the D14 among its other parts. Its parts include 53 resistors, 53 diodes, 7 capacitors, 7 ICs and 1 crystal.
Main components
4A13
TQFP-176(20x20)TQFP-176(20x20) Microcontrollers (MCU/MPU/SOC) ROHSAllwinner TechMicrocontroller Units (MCUs/MPUs/SOCs)74HC245D
SO-20-300mil-40℃~+125℃ 1 160uA 2V~6V 7.8mA 7.8mA 74HC 8 9ns@4.5V,50pF Bidirectional Tri-State SOIC-20-300mil Buffers, Drivers, Receivers, Transceivers ROHSNexperiaBuffers, Drivers, Receivers, TransceiversD12
SOD-123FLSchottky DiodesDIYI Elec TechD14
SOD-123F1A 40V 550mV@1A SOD-123F Schottky Diodes ROHSDIYI Elec TechSchottky Diodes
README
README.mdMini8086
A small, extensible Intel 8086 based computer system.
PCBs
Some boards are made with Eagle but then I switched to KiCad because my Eagle License covers only 2 layer boards and I don't like their new licensing model (it's too expensive for hobbyists). Schematics and layout are contained in the folders Eagle and KiCad.
Backplane (Eagle)
First revision of the system backplane with 6 slots and a power connector.
Backplane (KiCad)
Second revision of the backplane. Has 7 slots and two power connectors (one of them USB-C).
RAM board (Eagle)
RAM board with 512 KB SRAM.
Info board (KiCad)
A 16x2 HD44780 based LCD can be mounted to this board. Also contains some LEDs for important signals.
LED board (KiCad)
Information board with LEDs for the busses and all important signals.
CPU board Rev 1 (KiCad, "main")
First revision of the CPU board, contains socket for an Intel 8086 CPU, ROM and other important system chips:
- Intel 8259 interrupt controller
- Intel 8254 timer
CPU board Rev 2 (KiCad, "mainv2")
Second revision of the CPU board where I replaced most of the logic chips with an Altera CPLD. Also contains 1 MB SRAM so the external RAM board is not needed.
VGA board (KiCad)
Simple graphics card with 128 KB SRAM and VGA output. Supported modes:
- text mode 80x25 characters, 256 colors (resolution 640x400 pixels)
- 320x200, 256 colors
- 320x400, 256 colors
- 640x200, 256 colors
I/O board (KiCad)
- Slots for SD and MicroSD cards. Simple SPI controller implemented in an Altera CPLD.
- PS/2 keyboard connector
- RS232 connector
- I²C controller with a RTC module, BMP sensor module and EEPROM connected.
Parts
121| Qty | Value | Footprint | References |
|---|---|---|---|
| 53 | 300 | Resistor_SMD:R_1206_3216Metric | R1, R2, R10, R11, R12, R13, R14, R15, R16, R17, R18, R19, R20, R21, R22, R23 +37 |
| 7 | 100n | Capacitor_SMD:C_1206_3216Metric | C1, C2, C3, C4, C5, C6, C7 |
| 7 | 74HC245 | Package_SO:SO-20_12.8x7.5mm_P1.27mm | U1, U2, U3, U4, U5, U6, U7 |
| 1 | A0 | LED_SMD:LED_0603_1608Metric | D22 |
| 1 | A1 | LED_SMD:LED_0603_1608Metric | D19 |
| 1 | A10 | LED_SMD:LED_0603_1608Metric | D17 |
| 1 | A11 | LED_SMD:LED_0603_1608Metric | D14 |
| 1 | A12 | LED_SMD:LED_0603_1608Metric | D11 |
| 1 | A13 | LED_SMD:LED_0603_1608Metric | D8 |
| 1 | A14 | LED_SMD:LED_0603_1608Metric | D5 |
| 1 | A15 | LED_SMD:LED_0603_1608Metric | D2 |
| 1 | A16 | LED_SMD:LED_0603_1608Metric | D24 |
| 1 | A17 | LED_SMD:LED_0603_1608Metric | D21 |
| 1 | A18 | LED_SMD:LED_0603_1608Metric | D18 |
| 1 | A19 | LED_SMD:LED_0603_1608Metric | D15 |
| 1 | A2 | LED_SMD:LED_0603_1608Metric | D16 |
| 1 | A3 | LED_SMD:LED_0603_1608Metric | D13 |
| 1 | A4 | LED_SMD:LED_0603_1608Metric | D10 |
| 1 | A5 | LED_SMD:LED_0603_1608Metric | D7 |
| 1 | A6 | LED_SMD:LED_0603_1608Metric | D4 |
| 1 | A7 | LED_SMD:LED_0603_1608Metric | D1 |
| 1 | A8 | LED_SMD:LED_0603_1608Metric | D23 |
| 1 | A9 | LED_SMD:LED_0603_1608Metric | D20 |
| 1 | D0 | LED_SMD:LED_0603_1608Metric | D39 |
| 1 | D1 | LED_SMD:LED_0603_1608Metric | D37 |
| 1 | D10 | LED_SMD:LED_0603_1608Metric | D36 |
| 1 | D11 | LED_SMD:LED_0603_1608Metric | D34 |
| 1 | D12 | LED_SMD:LED_0603_1608Metric | D32 |
| 1 | D13 | LED_SMD:LED_0603_1608Metric | D30 |
| 1 | D14 | LED_SMD:LED_0603_1608Metric | D28 |
| 1 | D15 | LED_SMD:LED_0603_1608Metric | D26 |
| 1 | D2 | LED_SMD:LED_0603_1608Metric | D35 |
| 1 | D3 | LED_SMD:LED_0603_1608Metric | D33 |
| 1 | D4 | LED_SMD:LED_0603_1608Metric | D31 |
| 1 | D5 | LED_SMD:LED_0603_1608Metric | D29 |
| 1 | D6 | LED_SMD:LED_0603_1608Metric | D27 |
| 1 | D7 | LED_SMD:LED_0603_1608Metric | D25 |
| 1 | D8 | LED_SMD:LED_0603_1608Metric | D40 |
| 1 | D9 | LED_SMD:LED_0603_1608Metric | D38 |
| 1 | Edge72 | Mini8086:BUS_72 | X1 |
| 1 | IRQ1 | LED_SMD:LED_0603_1608Metric | D48 |
| 1 | IRQ3 | LED_SMD:LED_0603_1608Metric | D47 |
| 1 | IRQ4 | LED_SMD:LED_0603_1608Metric | D46 |
| 1 | IRQ5 | LED_SMD:LED_0603_1608Metric | D45 |
| 1 | IRQ6 | LED_SMD:LED_0603_1608Metric | D44 |
| 1 | IRQ7 | LED_SMD:LED_0603_1608Metric | D43 |
| 1 | NMI | LED_SMD:LED_0603_1608Metric | D41 |
| 1 | RESET | LED_SMD:LED_0603_1608Metric | D3 |
| 1 | TMR2 | LED_SMD:LED_0603_1608Metric | D42 |
| 1 | ~BHE | LED_SMD:LED_0603_1608Metric | D53 |
| 1 | ~IO | LED_SMD:LED_0603_1608Metric | D6 |
| 1 | ~MEMRD | LED_SMD:LED_0603_1608Metric | D49 |
| 1 | ~MEMWR | LED_SMD:LED_0603_1608Metric | D50 |
| 1 | ~RD | LED_SMD:LED_0603_1608Metric | D52 |
| 1 | ~VGA_IO | LED_SMD:LED_0603_1608Metric | D9 |
| 1 | ~VGA_MEM | LED_SMD:LED_0603_1608Metric | D12 |
| 1 | ~WR | LED_SMD:LED_0603_1608Metric | D51 |
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Questions
How big is the Led board PCB?
It measures 99.8 × 100.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Led board use?
121 parts, built around the A13, 74HC245D, D12 and D14. 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 Led board KiCad files?
From the svpetry/Mini8086 repository on GitHub, at the commit this page was made from: the board is KiCad/led_board/led_board.kicad_pcb and its schematic KiCad/backplane/backplane.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Led board design in my own project?
Its repository states no licence, so its author keeps all rights: ask svpetry before reusing the design.