Note: The 6809 CPU Card is supplied in Kitset form only (assembly required). The base price is for the double-sided silkscreened 6809 CPU Card PCB ONLY. The optional packs provide some key components only. Other components are also required to make a complete 6809 CPU Card Kitset. See BOM below (and photo).

What is Minimalist Europe Card Bus

Europe Card Bus (ECB) is a Retro CPU Bus standard from the late 1970’s / early 1980’s.

The “Minimalist Europe Card Bus” (as I’ve called it), is a Retro 8-bit CPU Bus and PCB design standard that I decided to define & document. The purpose of which is to provide a modular platform for me to re-experience the fun of experimenting with the different 8-bit CPU’s, and the various video and peripheral devices, that I grew up with in the late 1970’s and early 1980’s.

My goal is that of a robust and modular design platform which allows me to create interchangeable PCB cards, based on time proven reliable bus connectors and modern low-cost prototype PCB manufacturing.

i.e. A robust, flexible, and low cost way for me to re-create some of the early microprocessor circuits, that I’d originally built using Wire-Wrap methods back in the day.

As evident from the name, the Bus itself is based on a Minimalist implementation of the original Europe Card Bus (ECB) standard.

Standardised Mechanical Specification for a Minimalist ECB “MECB” Board

MECB Standardised Board Design Parameters:

• Satisfy the 100mm square maximum board size, for low-cost prototype PCB manufacturing.
• Utilise the lower cost 64-pin (Row A&C) DIN 41612 type C connectors, for cost saving.
• Ensure the DIN 41612 connector(s) can be easily centred across the board width, grid aligned.
• Provide two standardised corner holes, on the edge opposing the right-angle DIN connector, to allow for attachment of card handles (to ease board insertion & extraction), or for board mounting – refer next point.
• Provide an additional two standardised corner mounting holes on the edge with the right-angle DIN connector, to provide a full set of four corner holes (to allow for stand-alone board mounting).
• Standardise PCB corner rounding, for sharp corner removal consistency across all boards & visual tidiness.

MECB Standardised Board Design Notes:

• PCB layout is designed utilising 0.127mm (5.0 mils) grid setting.
• Board size is 99.822mm, which represents the greatest even multiple of 0.127mm (i.e. multiple of 0.254mm – 10.0 mils), that will fit within the desired maximum 100mm board dimension.
• Standard M3 sized mounting holes were chosen. An additional two mid-edge located mounting holes are specified for the Backplane board only (to provide additional mechanical support).
• For reference, DIN 41612 connectors can utilise standard M2.5 mounting bolts (8mm length for the straight connectors, 10mm length for right angle connectors).
• Implemented as a KiCAD Template, to assist with simplifying the creation of each new MECB board design.

Please refer to the attached photo outlining all dimensions for the MECB Standardised Board Mechanical Specifications.

6809 CPU Card

The 6809 CPU Card has been tested with Motorola MC6809 (internal clock) and MC6809E (external clock), as well as Hitachi HD6309 and HD6309E processors. In addition, my videos demonstrate me successfully testing the system running at 4Mhz, with a Motorola MC68B09E processor (2Mhz rated), and a HD63C09E processor (3Mhz rated). Of course, over-clocking is not recommended, so if you want to replicate this please remember you do risk damage by exceeding manufacturer ratings.

What You Get

To satisfy different people's needs, I've split the 6809 CPU Card Kitset into optional add-on packs.

Firstly, note that the base price is for the double-sided silkscreened 6809 CPU Card PCB Only.

Then, you can add the optional Packs that might be helpful to you. Then, to complete the Kitset, you'll need to source the remaining parts to complete the BOM below.

Optional Hardware Pack includes:

• 1x Right-Angle Male DIN41612 364 Keyed Bus Connector
• 2x M2.5 Stainless Steel Bolt 10mm (2 required for Right Angle Connector)
• 2x M2.5 Stainless Steel Hexagonal Nut (for above Bolts)
• 4x 12mm Nylon PCB Spacer
• 8x 6mm Nylon Bolt (for Spacer mounting)

Optional Programmed ATF16V8 PLD Pack includes:

Either:

• An ATF16V8 PLD Chip Tested and Programmed for the 56K RAM + 8K ROM memory map (as used with the on-board AT28C256 ASSIST09 monitor example).

Or:

• An ATF16V8 PLD Chip Tested and Programmed for the 48K RAM + 16K ROM memory map (as used with the ROM Expansion Card usage example).

Optional Programmed AT28C256 EEPROM Pack includes:

• An AT28C256 EEPROM Chip Tested and Programmed with the ASSIST09 monitor.

6809 CPU Card BOM

The following is a full Bill Of Materials (BOM) to allow fully assembling your 6809 CPU Card.

Note that the PCB is supplied, and some select components are available in the three option packs. The rest of the components will need to be sourced by yourself.

Some components are of course optional. For example the IC Sockets, although I do highly recommend IC Sockets are used.

I have also included an indication of where I sourced my parts from, if this is of assistance.

The Video linked below provides a presentation of the v2.2 6809 CPU Card, as well as demonstrating the steps I took for assembly. An additional video can also be found detailing the current v2.3 CPU Card updates.

Via the Documentation link (below) you'll also find earlier 6809 CPU card development progress videos, and other videos presenting different components of the MECB retro 8-bit computing project.

Your 6809 CPU Card Kitset order is shipped in a robust cardboard carton with packing, for safe delivery via New Zealand International Air Parcel (see example shipping photo).

Note: Please visit the Documentation link (below) for more information on MECB, and for details of the various MECB Cards that have been design so far.