NABU Computer Specifications

Here are the NABU Zilog Z80 Personal Computer and Keyboard specifications. Please note: Any integrated circuit or monolithic integrated circuit chips marked with a * are in sockets on the motherboard.

Zilog Z80A Microprocessor*
The Zilog Z80 is a software-compatible extension and enhancement of the Intel 8080. The Z80 also became one of the most widely used CPUs in desktop computers and home computers from the 1970s to the mid-1980s.

  • Running at 3.58MHz
  • Interrupts: eight levels, maskable, mode 2 vectored
  • 64K DRAM – (System RAM) eight HM4864P-2
  • 4/8K EPROM – jumper select 4K or 8K
  • Comes with 4K EPROM standard

TMS9918 Video Display*
The TMS9918 is a video display controller (VDC) manufactured by Texas Instruments, in manuals referenced as “Video Display Processor” (VDP) and introduced in 1979.

  • Composite Color Video (NTSC Compatible)
  • TV RF Modulator (Ch 3 or Ch 4)
  • 16K DRAM – (Video RAM) eight TMS4116-15NL
  • 256 x 192 Resolution (Graphics)
  • 40 x 24 Text (TV Screen Readable)
  • 32 Sprite Planes (Animation Patterns)
  • 15 Colors (Plus Transparent)

AY-3-8910 Sound Generator*
The AY-3-8910 is a 3-voice programmable sound generator (PSG) designed by General Instrument in 1978, initially for use with their 16-bit CP1610 or one of the PIC1650 series of 8-bit microcomputers.

  • 3 Channels of Sound
  • Sound Effects, Music Synthesis, Alarms
  • TV Set Output (RF Modulator)
  • External Amplifier Output (Line level)

TR1863 High Speed UART*
Western Digital Universal Asynchronous Receiver/Transmitter (UART).

  • EIA RS-422 protocol
  • Full Duplex, 111 Kbits/sec
  • Network Serial Interface
  • 5-pin DIN connector
  • Can be modified for standard BAUD rates
  • Can be modified for RS-232/RS-485 protocols

D8251AC USART
NEC Corporation D8251AC Interface IC, UART.

  • EIA RS-422
  • Keyboard Serial Interface
  • 6-pin DIN connector

SN74LS Series Logic Chips
The original 7400-series integrated circuits were introduced by Texas Instruments with the prefix “SN” to create the name SN74xx. Due to the popularity of these parts, other manufacturers released pin-to-pin compatible logic devices and kept the 7400 sequence number as an aid to identification of compatible parts.

  • 32 Low Power Schottky Logic Chips

Keyboard (17″x7″x2.5″)

  • Charcoal gray, black keys
  • Durable plastic, full stroke keyboard with Alps switches
  • 2-key rollover, auto repeat
  • 2 DB-9 joystick connector ports

Computer I/O

  • 4 Card Slots
  • 30 pin 0.1″ SIP male header
  • For user I/O Circuits or Cards
  • Contains bi-directional data lines
  • Contains 16 decoded addresses each
  • Other signals: control, clocks, power

Audio Output

  • RCA phono connector
  • 10 KOhm output impedance
  • 1.5V p-p signal

Video Output

  • RCA phono connector
  • 75 Ohm 1V p-p, +/-6dB negative sync
  • Composite Video (NTSC Compatible)

External RF Input

  • Type-F connector
  • 75 Ohm CATV cable input
  • Input signal for normal TV viewing

TV RF Output

  • Type-F connector
  • ASTEC UM 1285-8 Modulator
  • 75 Ohm cable output
  • Video and Audio are RF modulated
  • Ch 3 or Ch 4 modulator switch
  • Software switchable output (TV/Computer)

Network Serial Interface

  • 5-pin DIN connector
  • RS-422 protocol, Full Duplex, 111 Kbits/sec

Keyboard Serial Interface

  • 6-pin DIN connector
  • Serial RS-422 protocol

Printer Interface

  • DB-15 connector
  • 8-bit parallel printer port with handshaking

Power Supply

  • 40 Watts AC/DC Switching Supply & Fan
  • +5V@2.5A/+12V@2.0A/-12V@0.1A
  • Sealed and separate from motherboard
  • Quiet cooling fan

Enclosure (18.5″x11″x4″)

  • Charcoal gray, with plastic front panel
  • Contains power supply & motherboard
  • 4-screw, easy open, easy access cover
  • Front: ON/OFF & reset switches
  • Front: 4 LEDs, 3 are programmable
  • Back: 7 connectors & 4 I/O panels
  • All metal case, effective RF shielding

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