4 layers152.4 × 114.3 mm
2 layers101.8 × 68.2 mm
Mega68k
stevegg/mega68k168k processor married to an Arduino for diabolical purpose
- Size
- 101.8 × 68.2 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 23
- Nets
- 126
- Pads
- 342
- Tracks, vias
- 2,181, 99
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 21 Jul 2022
- Updated
- 20 Aug 2022
Overview
Mega68k is an open-source printed circuit board by stevegg, from the stevegg/mega68k repository on GitHub. It is a 2-layer board of 101.8 × 68.2 mm with 23 parts on 126 nets, routed with 2,181 tracks and 99 vias.
It is built around the AS6C4008-55PCN and MC68681FN. Its parts include 7 capacitors, 3 ICs, 3 connectors, 2 resistors and 2 switches. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
2README
README.mdSteve's Mega68k
This project was inspired by others. It's the unholy union of an Motorola MC68000 CPU and MC68681 DUART with an Arduino Mega along with an AdaFruit SD Card breakout. This is my attempt to bootstrap building a single board CPU with appropriate software to make it interesting. My goals are to get the software to a point where it can run both CP/M 68k and a scaled down version of Linux.
Right now there are 2 software projects:
- Mega68k freerun - implementing a simple freerun mode
- Mega68k simpleLopp - implementing a simple loop and using the arduino as ROM.
Both of these are in the software sub-directory. The hardware sub-directory contains the KiKad 6.0 project along with the required symbol and footprint libraries and the gerbers.
For Arduino software development I'm using VSCode and the platformio plugin. This provides a pleasant and smooth development experience.
For assembler I'm using Easy68k...this provides a less smooth and pleasant development experience but it does work and the simulation is quite useful.
Parts
23| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | .1uF | Capacitor_SMD:C_0603_1608Metric | C2, C3, C6, C7 |
| 2 | 12pf | Capacitor_SMD:C_0603_1608Metric | C4, C5 |
| 1 | 100uF | Capacitor_SMD:CP_Elec_4x5.4 | C1 |
| 1 | 10k | Resistor_SMD:R_0603_1608Metric | R6 |
| 1 | 220 | Resistor_SMD:R_0603_1608Metric | R1 |
| 1 | 3.6864 | Crystal:Crystal_HC49-U_Vertical | Y1 |
| 1 | ARD RESET | Button_Switch_THT:SW_PUSH_6mm | SW1 |
| 1 | AS6C4008-55PCN | Package_SO:SSOP-32_11.305x20.495mm_P1.27mm | U1 |
| 1 | Arduino_Mega2560_Shield | Arduino:Arduino_Mega2560_Shield | XA1 |
| 1 | CPU_RESET | Button_Switch_THT:SW_PUSH_6mm | SW2 |
| 1 | CXO_DIP8 | Oscillator:Oscillator_DIP-8 | X1 |
| 1 | Debug | Connector_PinHeader_2.54mm:PinHeader_2x34_P2.54mm_Vertical | J4 |
| 1 | KiCad-Logo2_8mm_SilkScreen | Symbol:KiCad-Logo2_8mm_SilkScreen | Logo1 |
| 1 | MC68008FN8 | Package_LCC:PLCC-52_THT-Socket | IC1 |
| 1 | MC68681FN | Package_LCC:PLCC-44_THT-Socket | U2 |
| 1 | OSHW-Logo2_9.8x8mm_SilkScreen | Symbol:OSHW-Logo2_9.8x8mm_SilkScreen | Logo2 |
| 1 | PWR | LED_SMD:LED_1206_3216Metric | D1 |
| 1 | SD Card | Connector_PinSocket_2.54mm:PinSocket_1x08_P2.54mm_Vertical | J3 |
| 1 | Serial 1 | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J5 |
Questions
How big is the Mega68k PCB?
It measures 101.8 × 68.2 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Mega68k use?
23 parts, built around the AS6C4008-55PCN and MC68681FN. 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 Mega68k KiCad files?
From the stevegg/mega68k repository on GitHub, at the commit this page was made from: the board is hardware/Mega68k.kicad_pcb and its schematic hardware/Mega68k.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Mega68k design in my own project?
Its repository states no licence, so its author keeps all rights: ask stevegg before reusing the design.
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