Scramble

Estimated reading time: 4 min

Scramble

Scramble, released in 1981, was the worlds first multi level shoot-em-up. Frogger, also released in ’81, is probably one of the most well-known arcade games today, with numerous conversions to other platforms.

Here is a VHDL model of the original hardware so the games can be re-created in modern FPGAs.

The games uses two Z80 processors. I designed a quad Z80 core designed for Xevious which time division multiplexes the majority of the core and is only a little larger than a single Z80. However for simplicity here two Z80s are instantiated, and it still fits easily into the Spartan3 500E on the eval board, the whole design taking about 68%.

The design also includes two AY-3-8910 sounds chips and two 8255 PIA chips. I have attempted to digitally model the filters on the audio board as well.

If anybody has a real board running can they let me know if the stars and audio are correct – we aim for 100% accuracy here….

Currently supported games include:

* Scramble (Stern)
* Armoured Car
* Amidar
* Super Cobra
* Frogger

Experimental INI’s are also provided for:

* The End (Konami)
* The End (Stern)

 

## Controls

### Joystick

Attach joystick to port 1. A second joystick is currently not supported.

### Virtual keyboard

The joystick in port 1 is emulated in parallel using the virtual keyboard:

* Cursor up, down, left, right
* enter -> Fire
* space -> Fire 2 (bomb)
* key 5 -> Coin
* key 1 -> Start 1 Player
* key 2 -> Start 2 Player

## Video output

R1 and V4 both output 640×480 progressive at ~60 Hz on DVI (-A and -D) and HDMI, respectively.


## Acknowledgements

* Original FPGA conversion by Mike Johnson
* T80 core by Daniel Wallner, Mike Johnson

https://opencores.org/projects/t80

Please read the “Readme.md” file for documentation.
This core supports multiple games, INI files for each game and ROM set names are included.

IMPORTANT NOTE :
NO ORIGINAL ROM CONTENTS ARE IN THIS DISTRIBUTION. YOU WILL NEED THE ORIGINAL/ALTERNATIVE ROM FILES TO RUN THE SCRAMBLE GAME

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