Table of Contents

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Table of Contents

Z80 Rev0 Mezzanine Board for EPM240 Dev Board

Introduction

Features

Theory of Operation

Design Files

Software

Z80 Rev0 Mezzanine Board for EPM240 Dev Board

Note, Rev0 of Z80 Mezzanine board is superceded by rev1.1 of 3V Z80 Mezzanine board

Introduction

While Z80 is specified for 5V operation, selected CMOS Z80 are capable of running at 3.3V. This mezzanine board hosts such Z80 plus a 512K RAM and plugs on top of the EPM240 development board. The two-board Z80 computer can run RomWBW.

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Features

CMOS Z80 selected for 3.3V operation

512K RAM

512 byte flash embedded in EPM240 can boot RomWBW

ACIA emulation in EPM240

SD card interface

RTC module based on DS1302

I2C interface

RomWBW capable

www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_epm240dev_3vz80_3vz80_romwbw_annotated.jpg

Theory of Operation

Boot from embedded 512-byte flash, etc, etc…place holder.

www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_epm240dev_3vz80_bootsd_romwbw.jpg

Design Files

Schematic

Gerber photoplot files

EPM240 design files

RomWBW SD bootstrap code resided in EP240's embedded flash

EPM240 design files with fast SD bootstrap (6 seconds), but no RAM disk at drive A

Bill of Materials

Software

RomWBW image for 3VZ80. The RomWBW will be booted at power up. It takes 23 seconds to load and boot RomWBW from reset.