The NABU PC is a computer that was designed to work with the NABU network. The PC is based on the Z80 architecture and has the Yamaha AY-3-8910 Programmable Sound Generator as well as the TMS9918 Video Display Processor, all components also found in the popular MSX range of computers.

The NABU network was designed by an Ottawa-based company called NABU Manufacturing. The idea was to develop a network to link home computers to cable television network that would supply a continuous, high speed stream of computer programs and information to the connected PCs. NABU thought that cable telivision was the ideal technology to deliver digital information services to homes and educational institutions because of the high bandwidth and the coverage in North America.

The NABU network was officially launched on Ottawa Cablevision in 1983, followed by Ottawa's Skyline Cablevision in 1984 and in 1985 by Sowa in Japan. The last was the result of the collaboration between NABU and the ASCII Corporation. NABU Network subscribers could rent or buy a NABU personal computer and a dedicated network adaptor. An ordinary TV would be the display monitor. THe user could choose from various applications and services including entertainment, information and guides, education, professional programs and games. There were also dedicated NABU magazines, newsletters, programming guides and user groups that would supply useful information.

Due to financial difficulties and low adoption rates, the NABU Network Corporation closed down its operations in 1983, only three years after the launch.

The NABU Network Adaptor is the interface between the NABU Personal Computer and the cable television network that enables software applications and other digital data to be downloaded from NABU’s back-end systems. The NABU Preservation Project has released an Internet Adaptor which emulates the NABU Network Adaptor. This allows the NABU PC to download applications and data via the Internet. This section describes how to create an adaptor cable that allows a NABU PC to be connected via RS-422 to a system running the Internet Adaptor software.

The ADAPTOR port on the back of the NABU Personal Computer implements a full-duplex RS-422 interface, which requires 4 wires for communication between devices. Because of the high transmission (baud) rates involved, a twisted-pair shielded cable is highly recommended. Category 5 cable (as used in Ethernet cabling) is available both as shielded twisted pair and as unshielded twisted pair and generally exceeds the recommendations for RS-422, making it an excellent choice. When using shielded cable, the shielding must only be connected to one of the connectors to avoid a ground loop.

There are several USB to RS-422 devices available, this section uses a DSD Tech SH-U11H Isolated USB to RS422 adapter. The shielding on this device is excellent, and it has screw terminals that allow for an easy DIN cable connectin without having another connector in between (some USB to RS-422 use a DB-9 connector). I have used a midi cable that I cut one of the ends off, and then connected the exposed wires to the screw-terminals. Just make sure you connect the wires properly. If you can't make out which pin goes to which wire, use a multi-meter in the "test" mode to find out.

After you complete the cable, download the Internet Adapter Here and you can download software, run Cloud CP/M and more.

The TMS9918 is a series of video display controllers (VDC) manufactured in 1979 by Texas Instruments, also refered to as 'Video Display Processor' (VDP). The TMS9918 and its variants were used in the ColecoVision, CreatiVision, Memotech MTX, MSX, NABU Personal Computer, SG-1000/SC-3000, Spectravideo SV-318, Spectravideo SV-328, Sord M5, Tatung Einstein, Texas Instruments TI-99/4, Casio PV-2000, Coleco Adam, Hanimex Pencil II, and Tomy Tutor.

Key Features:

• 256x192 pattern based color pixels per screen
• 16 different colors
• 8-bit memory mapped CPU interface
• No need for DMA, CPU can access VRAM
• 32 single color Sprites per screen (4 per scanline)

Variants:

• TMS9918A - 60Hz output, NTSC video
• TMS9928A - 60Hz output, YPbPr video
• TMS9929A - 50Hz output, YPbPr video
• TMS9118 - Different RAM than TMS9918A, otherwise identical
• TMS9128 - Different RAM than TMS9928A, otherwise identical
• TMS9129 - Different RAM than TMS9929A, otherwise identical

The AY-3-8910 is a 3-voice Programmable Sound Generator, or PSG. It was designed by General Instrumet in 1978 for use with their own 8-bit PIC1650 and their 16-bit CP1610 computers.

The PSG is widely used in many arcade cabinets, pinball machines, and many micro-computers. Here is a list of some of the major brands of computer that used the AY-3-8910:

• Intellivision
• Vectrex
• Amstrad CPC range
• Oric-1
• Color Genie
• Elektor TV Games Computer
• All MSX-1 and MSX-2 computers
• ZX Spectrum home computers

General Instrument spun of MicroChip Technology in 1987 and the chip was sold under the MicroChip brand, and licensed to Yamaha as the YM2149F which the Atari ST range of computers use. Functionally the PSG is very similar to the Texas Instruments SN76489.

Variants:

• AY-3-8910
  Comes with 2 general purpose 8-bit parallel I/O ports, used for Keyboard and Joystick in for instance MSX.
• AY-3-8912
  Same chip, but in a 28-pin package. Parallel port B is not connected to save cost and space.
• AY-3-8913
  Same chip, but in a 24-pin package. Both parallel ports are not connected.
• AY-3-8914
  The AY-3-8914 has the same pinout and is in the same 40-pin package as the AY-3-8910, except the control registers on the chip are shuffled around, and the 'expected input' on the A9 pin may be different. It was used in Mattel's Intellivision console and Aquarius computer.
• AY-3-8930
  Backwards compatible but BC2 pin is ignored
YM2149F
Yamaha Produced chip, same pin-out as the AY-3-8910, but pin 26 could halve the master clock. Can be used to replace the AY-3-8910 if pin 26 is left disconnected.
• YM3439-D
  CMOS version of the Y2149 in 40-pin DIP
• YM3439-F
  CMOS version of the Y2149 in 44-pin QFP
• YMZ294
  Variant of the YM3249 in an 18-pin package. Parallel ports not connected, and all sound channels mixed on 1 port.
• T7766A
  Toshiba variant of the AY-3-8910, fully compatible. Used in some MSX models.
• Winbond WF19054, JFC95101, and File KC89C72: Fully compatible versions of the AY-3-8910 produced for slot machines.

The Z80 quickly became popular in the personal computer market, with many early personal computers, such as the TRS-80 and Sinclair ZX80, using the Z80 as their central processing unit (CPU). It was also widely used in home computers, such as the MSX range, SORD, and the Amstrad CPC, as well as in many arcade games. Additionally, it was also used in other applications such as industrial control systems, and embedded systems. The Z80 was widely used until the mid-1980s, when it was gradually replaced by newer microprocessors such as the Intel 80286 and the Motorola 68000.

The Z80 microprocessor was developed by Zilog, a company founded by Federico Faggin in 1974. The Z80 was released in July 1976, as a successor to the Intel 8080. It was designed to be fully compatible with the 8080, but also included new features such as an improved instruction set, more powerful interrupts, and a more sophisticated memory management system.

The Z80 quickly became popular in the personal computer market, with many early personal computers, such as the TRS-80 and Sinclair ZX80, using the Z80 as their central processing unit (CPU). It was also widely used in home computers, such as the MSX range, SORD, and the Amstrad CPC, as well as in many arcade games. Additionally, it was also used in other applications such as industrial control systems, and embedded systems. The Z80 was widely used until the mid-1980s, when it was gradually replaced by newer microprocessors such as the Intel 80286 and the Motorola 68000. The design was licensed to Synertek and Mostek as well as the European SGS.

The Z80s instruction set is binary compatible with the Intel 8080, so that 8080 code such as the CP/M Operating System and Intel's PL/M compiler for the 8080 can run unmodified on the Z80. The Z80 had many enhancements over the 8080 such as 16-bit data movement instructions, block copy and block I/O instructions, single bit addressing of all registers, IX/IY offset registers, better interrupt system and a complete duplicate register file for context switching during an interrupt.