N8VEM

N8VEM is a homebrew computing project. It features a variety of free and open hardware and software. N8VEM builders make their own homebrew computer systems for themselves and share their experiences with other homebrew computer hobbyists. N8VEM homebrew computer components are made in the style of vintage computers of the mid to late 1970s and early 1980s using a mix of classic and modern technologies. They are designed with ease of amateur assembly in mind.

There are several N8VEM designs starting with a single-board computer carrying a Z80 microprocessor designed to run CP/M and similar operating systems. It was created in 2008 by Andrew Lynch. Contrasted with the P112, which has some surface-mount components, the N8VEM SBC uses only through-hole components.

The N8VEM boards are designed with the free KiCad Electronic design automation (EDA) toolset. Printed Circuit Board routing provided by FreeRouting.net Software is developed in Z80/8085 assembly language using the following toolset for MSDOS called Telemark Cross Assembler (a.k.a. TASM) A major design goal is to use freely available tools to the maximum extent possible. The Printed Circuit Board design is supplemented using component libraries available here KiCad Libraries, specifically the Zilog Z80 CPU and Intel 8255 PPI chips.

Encourages low cost development and assembly by hobbyist amateurs using common tools such as 25 watt soldering iron, multimeter, logic probe (optional), and common hand tools. An oscilloscope is recommended but not required. Some basic electronic skills are helpful although the Printed Circuit Board is designed for relative beginners.

There are numerous N8VEM components available including an ECB backplane board is available to allow expansion boards to be used. Other components include video boards, disk controllers, peripheral expansion, and prototyping. The N8VEM homebrew computing project started producing several S-100 bus boards in collaboration with S100Computers.com

• N8VEM Single Board Computers

1. SBC V2 (Z80, UART, PPI, RAM with battery backup, ROM, RTC)
2. SBC-188 (80C188 10-25Mhz, UART, PPI, RAM with battery backup, ROM, RTC, FDC)
3. Z8S180 Home Computer (Z8S180 33mhz, UART, ROM, RTC, Dual Interrupt controllers, Floppy, SD Card, 1Mb RAM, AY-3-8910 sound, TMS9918A video)
4. Z80 S-100
5. m68k S-100 (In Progress)
6. 8086 S-100 (In progress)
7. 6502/6809 ECB + carrier boards for other cpu's (?)

• N8VEM ECB Expansion Peripherals

ECB Backplane (compact stand alone with 8 DIN 41612 slots)

ECB Bus Monitor (single step, address trap, bus status)

Disk IO (FDC & IDE drive expansion)

Zilog Peripherals (CTC, DART, dual PIOs)

Video Display Unit (80x25 character mode video)

Prototyping board with IO decode (buffered with labeled signal connectors)

ECB Extended backplane (12 slot with 3U mounting features)

DSKY (monitor/boot loader Hex LED display and keypad)

Sprites, Color Graphics, & Sound (TMS9918, AY-3-8910, joystick/paddle interface)

Prop IO (VGA, PS/2 keyboard, PS/2 mouse, micro SD, prototyping area)

Cassette Interface (KCS audio cassettes)

4MEM (4MB SRAM expansion for SBC-188)

PPIDE (SBC parallel expansion port IDE interface)

Juha SD (SBC SD card for mass storage)

MSX Cartridge reader (load contents of MSX cartridges)

MSX Cartridge (8K, 16K, & 32K EPROMs)

uPD7220 V2 prototype (16 color video display)

RAM-Floppy (4MB SRAM floppy drive replacement)

4PIO (64 GPIO input/output board)

ECB to Z80 socket adapter (connect ECB boards directly to Z80 CPU)

6x0x host processor (6809/6802/6502 CPU with ECB interface)

6x0x IO mezzanine (ACIA, dual PIA, PTC, power, and expansion bus interface)

6x0x ECB backplane (use ECB peripherals with stand alone 6x0x system)

As of April 2011, boards are available for purchase. There is an active community development forum (N8VEM Google Discussion Group) from which additional board designs have been developed. There is active development of new boards underway.

External links

• The N8VEM Homepage
• N8VEM Google Discussion Group

Sources

• N8VEM single board Z80 computer