Note: The MECB Motorola 6802 CPU Card is supplied in Kitset form only (assembly required). The base price is for the double-sided silkscreened 6802 CPU Card PCB ONLY. The Optional Packs provide all of the components for a full 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 boards 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 KiCAD Templates, 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.

Motorola 6802 (6800) CPU Card

The "6802 CPU Card" expands on the various existing Motorola based MECB CPU Cards, by introducing the original Motorola MC6800 8-bit processor in it's 1977 released MC6802 variant which includes the dual-phase clock, on-chip.

The MC6802 took the original MC6800 and added a dual-phase clock generator, on-chip. The original MC6800 needed a MC6875 external DIP16 clock generator, which is also now becoming harder to find.

The MC6802 also added an on-chip 128 bytes of RAM. As this CPU Card has no need for the on-chip 128 bytes of RAM, it is disabled via the RE (RAM Enable) pin.

As a result, this CPU Card can also use the MC6808 variant, which is simply a MC6802 without the on-chip 128 bytes of RAM.

Either way, you effectively have an original MC6800 8-bit processor, for experimenting with the original Motorola 8-bit CPU from the 1970's.

Also, just like the original MC6800, the MC6802 is available in 3 speed variants. First the original MC6802, which is rated for 1MHz clock, then the MC68A02 which is 1.5MHz rated, and finally the MC68B02 which is 2MHz rated.

For the Optional Semiconductor Pack I've included the fastest MC68B02 version (2MHz).

The Programmed AT28C256 EEPROM Pack provides a DigiBug monitor, which was based combining and further developing a number of significant advancements from the original Motorola MIKBUG Monitor firmware.

The DigiBug Monitor provides everything you need to get started with loading and running your own 6800 programs.

In summary, this CPU Card enables exploring the original 6800 CPU, with a fully loaded 64K memory space!

What You Get

To satisfy everyone's differing needs, I've split the 6802 CPU Card Kitset into Optional add-on Packs.

Firstly, note that the base price is for the double-sided silkscreened 6802 CPU Card PCB Only.

Then, you add Optional Packs to complete your Kitset, depending on your parts requirements.

Adding all of the Optional Packs provides all of the components for a full Kitset.

Please view the second photo, for a visual representation of the available Optional Packs.

Optional Hardware Pack includes:

• 1x Right-Angle Male DIN41612 364 Keyed Bus Connector (J1)
• 2x M2.5 Stainless Steel Bolt 10mm (2 required for Right Angle Connector)
• 2x M2.5 Stainless Steel Hexagonal Nut (for above Bolts)
• 4x M3 Nylon PCB Spacer 12mm
• 8x M3 Nylon Bolt 6mm (for Spacer mounting)
• 2x 2-pin PCB Header (JP2,JP3)
• 1x 3-pin PCB Header (JP1)
• 1x 2-pin Jumper Cap (for JP1)
• 2x Tactile Switch 6mm (SW1,SW2)
• 1x 8-way DIP Switch DIP16 (SW3)

Optional Discrete Components Pack includes:

• 2x Resistor Network 4K7 SIP9 (RN1,RN2)
• 1x 0.22µf Capacitor 5mm (C1)
• 6x 0.1µf Capacitor 5mm (C2,C3,C4,C5,C6,C7)
• 1x Crystal Oscillator 8MHz 5V DIP8 (X1)

Optional Programmed ATF16V8 PLD Pack includes:

• 1x ATF16V8 PLD DIP20 (U1) - pre-Programmmed and Tested for the required glue-logic.

Optional Programmed AT28C256 EEPROM Pack includes:

• 1x AT28C256 32KB EEPROM DIP28 (U4) - pre-Programmed with DigiBug Monitor firmware.

Optional Semiconductor Pack includes:

• 1x pre-Tested / Verified operational Motorola MC68B02 2MHz CPU DIP40 (U3)
• 1x 74HCT688 DIP20 (U2)
• 1x W24512K 64KB SRAM SDIP32 (U5)
• 2x TC1232CPA DIP8 (U6,U7)

Optional IC Socket Pack includes:

• 1x DIP40 IC Socket (for U3)
• 1x DIP28 IC Socket (for U4)
• 2x DIP20 IC Socket (for U1,U2)
• 1x DIP28 Narrow IC Socket (for U5)
• 1x DIP4 IC Socket (for U5)
• 3x DIP8 IC Socket (for U6,U7,X1)

6802 CPU Card BOM

The following is the full Bill Of Materials (BOM) to allow fully assembling your 6802 CPU Card Card.

Note that the PCB is supplied, and all components required are available in the Optional Packs.

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

Via the Documentation link (below) you'll also find more information on the MECB system and other available Cards, as well as videos presenting different components of the MECB retro 8-bit computing project.

Default (PCB Only)

Optional Packs

Your 6802 CPU Card Kitset order is shipped in a robust cardboard carton with packing, for safe delivery via New Zealand International Tracked Air Parcel (see example shipping photo). I'll also email to you, photos of both your order content and your shipped parcel, with my shipping notification.

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.

We pride ourselves with our "Next Business Day" Shipping Policy, and robust carton packaging. We also build to order, so if you order items with an "Assemble it for me" option selected, it may slightly delay shipping (while we build it for you).