CPU Speed control

Acceleration, or Turbo mode, allows the Next to run at faster clock speeds than a standard Spectrum.

Acceleration is enabled via Peripheral 2 Register ($06) and configured via CPU Speed Register ($07), or via a user control. There are four potential settings:

• Turbo off, or turbo on and $07 set to #00: 3.5 Mhz.
• Turbo on, $07 set to #01: 7 Mhz. (Standard for Pentagon).
• Turbo on, $07 set to #10: 14 Mhz.
• Turbo on, $07 set to #11: 28 Mhz. Some features, such as Layer 2 drawing, are disabled at this speed.