MB020, A 68020-based Motherboard

MB020 is a 4“x4” 68020-based motherboard with 3 RC2014 expansion slots. It allows RC2014 users to reuse their existing hardware to explore the 68020 processor.

• MC68020
• 4/16 meg 72-pin SIMM DRAM
• 66.67Hz (14.7456MHz clock) level 1 autovector interrupt
• Three RC2014 expansion slots

MB020 consists of a 4“x4” motherboard populated with 68020, EPM7128S, SIMM72 socket and 3 RC2014 expansion slots. The purpose is to reuse the existing RC2014 boards to explore MC68020. To that end, the boot ROM, I/O, mass storage will be the existing RC2014 boards. A 68020 monitor will be developed for the boot ROM so it can load files, display & modify memory and registers, and run applications. The I/O can be RC2014 SIO2 or 68B50 boards and a RC2014 CF board can be added to run CP/M68K.

Schematic

Gerber photoplots, 4-layer pc board

Gerber photoplots mb020_r1.zip ← 2-layer PCB is unreliable, replaced by 4-layer pc board.

Bill of Materials

Engineering change. An enginnering change is required to connect CPLD's reset to 68020 reset.

CPLD design files

Memory map

IDE68K ver 3.3

Karlab's 8K ROM, ACIA, and CF.

FRR512K modified as a combination board of ROM/ACIA/CF for MB020