Jupiter-II

Another Jupiter Ace computer clone

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.)

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)