/* Imported from Wayback Machine
   Original URL : https://www.retrobrewcomputers.org/doku.php?id=builderpages%3Aplasmo%3Amb020
   Snapshot date: 2026-04-06
   Generator    : wayback-archiver
*/

==== Table of Contents ====

[[#mb020_a_68020-based_motherboard|MB020, A 68020-based Motherboard]]

[[#introduction|Introduction]]

[[#features|Features]]

[[#functions|Functions]]

[[#design_info|Design Info]]

[[#software_tools|Software Tools]]

[[#example_configurations|Example Configurations]]

[[#section|]]

====== MB020, A 68020-based Motherboard ======

===== Introduction =====

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.

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=8ab640&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/mb020/dsc_56340214.jpg|{{https://www.retrobrewcomputers.org/lib/exe/fetch.php?w=600&h=560&tok=242639&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fbuilderpages%2Fplasmo%2Fmb020%2Fdsc_56340214.jpg?600x560|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_mb020_dsc_56340214.jpg}}]]

===== Features =====

MC68020

4/16 meg 72-pin SIMM DRAM

66.67Hz (14.7456MHz clock) level 1 autovector interrupt

Three RC2014 expansion slots

===== Functions =====

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.

===== Design Info =====

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:mb020:mb020_scm_rev0.pdf|Schematic]]

Gerber [[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:mb020:mb020_rev1.zip|photoplots, 4-layer pc board]]

<del>Gerber [[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:mb020:mb020_r0.zip|photoplots]]</del> [[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:mb020:mb020_rev1.zip|mb020_r1.zip]] ← 2-layer PCB is unreliable, replaced by 4-layer pc board.

Bill of Materials

[[builderpages:plasmo:mb020:ec_mb020_rev1|Engineering change]]. An enginnering change is required to connect CPLD's reset to 68020 reset.

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:mb020:mb020_r0_cpld_release.zip|CPLD]] design files

[[builderpages:plasmo:mb020:mem_map|Memory map]]

===== Software Tools =====

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:mb020:ide68k_v3_3.zip|IDE68K ver 3.3]]

===== Example Configurations =====

Karlab's [[builderpages:plasmo:mb020:configuration_a:cofiga_home|8K ROM, ACIA, and CF]].

[[builderpages:plasmo:frr512k:rev0:mb020combo|FRR512K modified]] as a combination board of ROM/ACIA/CF for MB020