Note: The MECB Motorola 68008 CPU Card is supplied in Kitset form only (assembly required). The base price is for the double-sided silkscreened 68008 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 68008 CPU Card

The "68008 CPU Card" expands on the existing Motorola 6809 based CPU Cards, introducing the relatively powerful 16/32bit internal Motorola 68008 processor, together with up to 2MB of linear addressed onboard memory, as well as compatibility with the MECB bus.

This allows utilising existing MECB peripheral cards, and also allows further expansion of the memory via MECB (if required).

This CPU Card is likely to be the most powerful CPU Card designed for the 8-bit MECB platform. Effectively shoe-horning a 16/32 bit processor onto an 8-bit bus.

But, more importantly, this CPU card provides the means to experiment with the Motorola 68K ISA (Instruction Set Architecture), on our MECB platform.

The Programmed SST39SF040 PLCC32 FLASH ROM Pack provides the Motorola TUTOR 1.3 Monitor / Debug firmware, together with an Enhanced BASIC Interpreter (accessed via the added BA TUTOR command).

The TUTOR Monitor provides everything you need to get started with debugging and running your M68K programs.

What You Get

To satisfy everyone's differing needs, I've split the 68008 CPU Card Kitset into Optional add-on Packs.

Firstly, note that the base price is for the double-sided silkscreened 68008 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)
• 1x JTAG IDC Connector 2x5pin PCB Straight (J2)
• 1x 2-pin PCB Header (JP1)
• 1x 3-pin PCB Header (JP2)
• 1x 2-pin Jumper Cap
• 1x Tactile Switch 6mm (SW1)
• 1x Heatsink 14x14x6mm w/Thermal Tape (for U2)

Optional Discrete Components Pack includes:

• 1x Resistor Network 4K7 SIP9 (RN1)
• 7x 0.1µf Capacitor 5mm (C1,C2,C3,C4,C5,C6,C7)
• Crystal Oscillator 10MHz 5V DIP8 (X1)

Optional Programmed ATF1502 CPLD Pack includes:

• 1x ATF1502AS CPLD PLCC44 (U1) - pre-Programmmed and Tested for the required glue-logic.

Optional Blank SST39SF040 PLCC32 FLASH ROM Pack includes:

• 1x SST39SF040 512KB FLASH ROM PLCC32 (U6) - pre-Programmed with TUTOR 1.3 Monitor / Debug firmware, together with an Enhanced BASIC Interpreter.

Optional Blank SST39SF040 PLCC32 FLASH ROM Pack includes:

• 1x pre-Tested SST39SF040 PLCC32 packaged 512KB FLASH ROM, ready for you to program with your desired content, either for the ROM0 or ROM1 socket.

Optional Semiconductor Pack includes:

• 1x pre-Tested / Verified operational MC68008FN10 (10MHz) CPU PLCC52 (U2)
• 1x TC1232CPA DIP8 (U3)
• 1x AS6C4008 512KB SRAM DIP32 (U4)

Optional 2nd AS6C4008 512KB RAM Pack includes:

• 1x AS6C4008 512KB SRAM DIP32 (U5), intended for the RAM1 socket (to expand to full 1MB RAM capacity on-board).

Optional IC Socket Pack includes:

• 1x PLCC44 Through-Hole IC Socket (for U1)
• 1x PLCC52 Through-Hole IC Socket (for U2)
• 2x PLCC32 Through-Hole IC Socket (for U6,U7)
• 2x DIP32 IC Socket (for U4,U5)
• 2x DIP8 IC Socket (for U3,X1)

68008 CPU Card BOM

The following is the full Bill Of Materials (BOM) to allow fully assembling your 68008 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 68008 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). 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.