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Jupiter-II

Another Jupiter Ace computer clone

Jupiter-II KiCAD 3D view Jupiter-II keyboard KiCAD 3D view

Main differences from the original Jupiter Ace

  • Buffered composite video output
  • Reset button
  • Inversed video jumper selection
  • Two screen pages and two character sets area (selectable at the video expansion connector)
  • Reduced chip count with PLDs replacing several TTL logic
  • Additional signals in expansion connectors

For more information on the original Jupiter Ace computer and an extensive software collection visit The Jupiter Ace Archive

The Jupiter-II Expansion

See the Jupiter-II Expansion project for adding:

  • Video Colour
  • Programmable Sound Generator
  • 128K paged RAM
  • Serial Interface
  • FORTH vocabulary extension (Color, Memory Paging, Sound Generator, etc.)

Jupiter-II color expansion

Jumper Settings

Inverse Video Jumper

  • Jumper installed: Black text on white background (inversed)
  • Jumper removed: White text on black background (default)

ROM image selection Jumper

  • Jumper installed: Original Jupiter Ace 8K ROM image
  • Jumper removed: Boot with the Jupiter-II Expansion

The original Jupiter Ace 8K ROM image can be found at The Jupiter Ace Archive.

Connections

Power Supply

Connect a 7.5Vdc to 9 Vdc x 1A power supply. Center pin is positive.

A/V output

  • pin 1: Audio Output (BEEP)
  • pin 2: Common
  • pin 3: Composite Video Output

The video standard is 60Hz NTSC compatible but converting to 50Hz PAL by recoding the PLDs shall not be too difficult.

Tape I/O

  • pin 1: MIC output (for LOADing)
  • pin 2: Common
  • pin 3: EAR input (for SAVEing)

Expansion

50 pin header connector (2x25 female). Similar layout as the original Jupiter Ace with additional pins "-ROMSL" and "SPEAKER"

  • pin 1:GND , pin 2:GND
  • pin 3:-INT , pin 4:GND
  • pin 5:-NMI , pin 6:+9Vdc
  • pin 7:-HALT , pin 8:+5Vdc
  • pin 9:-MREQ , pin 10:-CLK
  • pin 11:-IORQ , pin 12:A11
  • pin 13:-RD , pin 14:A12
  • pin 15:-WR , pin 16:A13
  • pin 17:-BUSACK , pin 18:A14
  • pin 19:-WAIT , pin 20:A15
  • pin 21:-BUSRQ , pin 22:D4
  • pin 23:-RESET , pin 24:D3
  • pin 25:-M1 , pin 26:D5
  • pin 27:-RFSH , pin 28:A2
  • pin 29:A6 , pin 30:A10
  • pin 31:A5 , pin 32:A9
  • pin 33:A4 , pin 34:A8
  • pin 35:A3 , pin 36:A7
  • pin 37:A1 , pin 38:A0
  • pin 39:D0 , pin 40:D1
  • pin 41:D2 , pin 42:D6
  • pin 43:D7 , pin 44:-WE
  • pin 45:(n.c.) , pin 46:(n.c.)
  • pin 47:-ROMSL , pin 48:SPEAKER
  • pin 49:(n.c.) , pin 50:(n.c.)

(n.c.) means not connected

-ROMSL (in) Disables internal ROM chip when connected to +5V

SPEAKER (out) TTL level Speaker signal (BEEP)

Video Expansion

30 pins header connector (2x15 female). Similar layout as the original Jupiter Ace with some additional pins.

  • pin 1:VA3 , pin 2:VA0
  • pin 3:VA5 , pin 4:VA4
  • pin 5:VD2 , pin 6:VD3
  • pin 7:VD1 , pin 8:VD4
  • pin 9:VA6 , pin 10:VD0
  • pin 11:VA2 , pin 12:VD7
  • pin 13:-VRAMWR , pin 14:VD5
  • pin 15:VA8 , pin 16:VA7
  • pin 17:VA9 , pin 18:VA1
  • pin 19:VD6 , pin 20:-VLOAD
  • pin 21:+5Vdc , pin 22:GND
  • pin 23:-CPAGE , pin 24:-SPAGE
  • pin 25:-SCRRAM , pin 26:-VSYNC
  • pin 27:BORDER , pin 28:-HSYNC
  • pin 29:LUMA , pin 30:BLANK

-VRAMWR (out) Video RAM write enable

-CPAGE (in) Character Generator page selection

-SPAGE (in) Screen page selection

-SCRRAM (out) Screen RAM enabled

-VSYNC (out) Vertical Video Synch

-HSYNC (out) Horizontal Video Synch

LUMA (out) Video Luminance

BLANK (out) Video Blanking (retrace blanking)

Tools used & file formats

  • Designed with Kicad
  • Programmable Logic Devices coded in CUPL language (compiled with WinCupl available for free at Microchip)