Shared Projects by sergiovl

Desktop SCSI Emulator

SHARP X68000 PicoPSU Power Adapter

The goal of this project is to provide a simple-to-use adapter to power your SHARP 68000 ACE computer with a PicoPSU. The idea is to simply desolder the wire harness from your old (and presumably dead) X68K PSU, connect it to the screw terminals on this board, plug in a PicoPSU, and shove that back into the original PSU case.

Provided are Gerber files so you can make the boards. I use DirtyPCBs and fabricating these as prototype boards seems to do the trick (and inexpensively).

A few notes on the BOM (build of materials) included in the project:

(1) The selected ATX power molex has 2 plastic stand-offs on the bottom. The board does not account for those. Just shave them off with a knife.

(2) The ATX power molex needs a good push to get it through the board.

(3) The board has 2 7-pin header rows for the screw terminals. The last (unlabeled) pin on 1 of the header rows does nothing so the BOM specifies 1 6-pin heaer and 1 7-pin header. You can obviously do 2 7-pin headers if you want.

(4) The BOM includes a socket for the 74HC04 inverter. This is obviously optional. I just like sockets.

This project is provided with a GNU public license. Please copy, modify, and re-distribute. If you have suggestions, please let me know!

This project builds on the original X68K_EZ_Pico_PSU by moving the AC-DC converter inside the original X68000 PSU case, making for a very clean, OEM look.

Introduction

The main board implements standard MSX2* functionality, as described in the specifications below. The main board is designed to be stacked under the keyboard PCB, thus creating a “keyboard computer” form factor typical for 1980’s home computers.

Specifications

• Processor: Zilog Z80 CPU (CMOS version - Z84C00) running at 3.58 MHz
• Memory:
  • RAM: 512 KiB SRAM, expandable to 4 MiB using an optional daugherboard. MSX* compatible memory pager. The RAM is mapped to slot 3-2
  • ROM: 256 KiB or 512 KiB Flash ROM. The ROM is mapped to the slot 0 and sub slots 3-0, 3-1, and 3-3
• Video: Yamaha V9938 or Yamaha V9958 VDP
  • 128 KiB Video RAM
  • Composite, S-Video, and RGB video outputs
• Audio: Yamaha YM2149 or General Instrument AY-3-8910 PSG
• Two MSX* compatible cartridge slots
• Keyboard, joysticks, printer and cassette recorder interfaces
• RTC: Ricoh RP5C01
• Microprocessor Supervisor:
  • Reset generation
  • RTC battery backup
• BIOS: C-BIOS

  Project

  https://github.com/skiselev/omega