Note: The MECB Backplane is supplied in Kitset form only (assembly required). The base price is for the double-sided silkscreened MECB Backplane PCB ONLY. Option packs are required to make a complete Backplane Kitset. So if you already have the required components, then you can just order the PCB only.

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.

MECB Backplane Design

Backplane Design Parameters:

• 4x 64-pin (Row A&C) DIN 41612 type C straight female backplane connectors, centred across the board width.
• A 5th Right Angle female DIN connector, to facilitate mounting a board horizontally for ease of access during hardware or software debugging and also for prototype board development etc. In addition, the horizontal connector could also allow for a future Backplane extension board.
• Multiple 5V power connector options, including a DC Power Connector, a modern USB-C Power Connector, and a Screw Terminal connector to support any other desired power source.
• A Power Switch to allow switching on/off the power to the backplane connectors.
• Some Backplane filter / smoothing capacitors, of 100uf & 10uf values, leaving the smaller 0.1uf typical bypass values to be located close to the IC’s on each MECB modular card.
• Use only through-hole components, in keeping with the early 8-bit retro MECB theme.

Backplane Design Notes:

• 6x M3 mounting holes are provided for mechanical support (as per the standardised Mechanical Specification).
• A USB-C receptacle module is mounted with pin headers (to facilitate through-hole components only).
• Low profile 100uf capacitors are desired (and supplied in the Components Pack), for a clean and tidy finish.

What You Get

To satisfy everyone's needs, I've split the Backplane Kitset into optional add-on packs.

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

Then you add optional packs to complete the Kitset, depending on your parts requirements.

Optional DIN Connectors + Bolts Pack includes:

• 4x Straight Female DIN41612 364 Keyed Bus Connectors
• 1x Right Angle Female DIN41612 364 Keyed Bus Connector
• 8x M2.5 Stainless Steel Bolt 8mm (2 required per Straight Connector)
• 2x M2.5 Stainless Steel Bolt 10mm (2 required for Right Angle Connector)
• 10x M2.5 Stainless Steel Hexagonal Nut (for above Bolts)

Optional Components Pack includes:

• 6x 12mm Nylon PCB Spacer
• 12x 6mm Nylon Bolt (for Spacer mounting)
• 2x 100ufd Low Profile Electrolytic Capacitors
• 1x 10ufd Capacitor
• 1x LED 5mm Green
• 1x 270 Ohm TH Resistor
• 1x Toggle Switch (for On / Off Backplane Power)
• 1x 2-way 5mm Screw Terminal Block
• 1x DC Power Jack PCB Mount
• 1x 4-pin Header (for USB-C Module mounting)
• 1x USB-C Power Socket Module - Please also see Note: (below) and optional USB-C Power Delivery (PD) compliant Smart Module “Upgrade”.

Note: The USB-C Power Socket Module is great for dumb Power Adpaters, like the Raspberry Pi USB-C Power Adapter (that I use). However, it will not work with smart USB-C PD compliant Power Supplies. For use with a smart USB-C Power Supply you will need to also select the "Upgrade" option below, for a PD (Power Delivery) compliant module.

Optional USB-C PD (Power Delivery) Smart Socket Module “Upgrade” includes:

• 1x USB-C PD3.0 compliant Smart Socket Module pre-configured for 5V operation. This is an "Upgrade" to the Components Pack, replacing the dumb 1x USB-C Power Socket Module (otherwise supplied in that pack). Please also see Note: (above).

MECB Backplane BOM

The following is a full Bill Of Materials (BOM) to allow fully assembling your MECB Backplane.

Note that the PCB is supplied, and all components are available in the optional packs.

Some components are of course optional. For example, the different Power Connection options. Although, I do recommend populating all connectors, as I've found the extra connectors useful for supplying power to other connected devices.

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

Your Backplane 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: Visit the Documentation link (below) for more information on MECB, including a v1.2 Update Video for the MECB Backplane (the video below covers only the original Backplane version), and also details of the various MECB Cards that have been design so far.