SP 0256 Simulation User guide (beta)

About the chip

SP0256 was a speech synthesis/decompression chip originally manufactured by General Instruments in the early 1980s. This particular specimen was used in the Intellivoice console add on and contains general game-related phrases.

Simulation Controls

The control buttons are on the upper-right of the screen. The function as follows:

• Play/Pause simulation

• Reset simulation

• Step Back (a half clock pulse)

• Step Forward (a half clock pulse)

• Advance 10000 steps

To increase the speed of the simulation, disable the redrawing with the "Animate during simulation" check-box (below model)

Visual Model

The visual model shows the chip's wiring and logic states based on a real die photo of the chip. Use x/z keys to zoom, and drag the mouse to pan.

The chip has five layers

• Metal: Grey

• Diffusion: Blue

• Vias: Light Blue (connect metal and diffusion)

• Transistors: Green

You can turn individual layers on/off at any time with the check boxes below the model.

You can click on nodes to highlight them and any transistors connected to them. Transistors that may affect the node's logical state become pink, while transistors controlled by the node become yellow.

Digital Output

Below the control panel is an oscilloscope trace of the sound output. The chip creates an analog waveform using Pulse-Width-Modulation and an external low-pass filter.

Keyboard Controls

P - Step Back

N - Step Forward

Z - Zoom In

X - Zoom Out

Interacting with the chip.

Load addresses or trigger test modes with the toggle checkboxes. Guide is still WIP. Note: stand-by reset and reset much be checked for chip to function.