the N8



The N8 is intended to be a “home brew” style computer in the style of early 1980's all-in-one home computers with a usable set of features such as color graphics, audio, an assortment of mass storage options, a variety of ports, etc. Although a bus expansion is supported no additional boards are required.

The N8 is designed so builders can assemble it themselves using common tools such as basic soldering iron, VOM, etc. It is a simple two-layer board construction using all commonly available plated-through-hole (DIP and PLCC) components without requiring any SMT skills, programmable logic devices, etc.

A quick summary of the N8 features:

ProcessorZ8S180 CPU (Z80 compatible, 33MHz max)
Memory1MB SRAM and 512K Flash boot ROM (in-circuit reprogrammable)
VideoTMS9918 Composite Color Video
SoundAY-3-8910 Sound Generator
Keyboard/MousePS/2 Keyboard and Mouse
Mass StorageIDE drives (including CF adapter) port, Floppy drives port (3.5“ @ 1.44M/720K, 5.25” @ 1.2M/360K), and SD socket
Expansion I/OTwo Serial ports, Parallel Printer port, Two MSX compatible Joystick ports, RTC w/NVRAM (configuration data), RS-485 networking port
OtherVarious diagnostic LEDs, “front panel” status indicators, buttons, with optional debugging hex display and keyboard (DSKY)

ROM Support included in

  • C-BIOS MSX Compatible BIOS
    • Various MSX Game Cartridges supported by C-BIOS


  • On release 2312 of the PCB the SD circuit was changed, so the MSX CBIOS needs to be recompiled with different settings to work with older boards
  • There have been reports of fragile/missing traces on the 4314 boards (U11-17 to U8-1) and on the 2312 boards (U58-13 to U24-2) both in the SD card circuit
  • The version of the MSX CBIOS has been tested on the 4314, 2312 and 2511 versions of the board.
  • Board versioning scheme is WWYY where WW is the week number and YY is the year number. So, 2312 means week 23 of year 2012.





Changes and Errata

Successful serial communication with the ZS180 requires the DCD to be low. On the N8 board DCD is pin 47 of the ZS180. This line is tied to ground via resistor R42 (2K2). This resistor value may be too high. If you are unable to see serial output then try bridging this resistor so pin 47 is connected to ground.

N8-2511 Jumper Settings Listing of the various Jumper Settings
N8-2511 BOM BOM for release 2511
N8-2511 Schematc Schematic
N8-2511 Board board
N8-2312 Schematic Schematic 2312 version
N8-2312 Board Board 2312 version
N8-4314 Board and Schematic ZIP Archive with build files for the 4314 version
MSX BIOS MSX BIOS Software (SD card now works with all versions of board, ROM is compiled for 2312 or newer)
YMPlayer YPlayer software
AVTest AVTest Software
N8 Laser Cut Acrylic Case Design N8 laser cut acrylic case SVG files and assembly pictures

boards/sbc/n8/n8.txt · Last modified: 2019/08/07 19:22 by jordi.solis
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