Turbo mode settings

Turbo control

Turbo control
Option Description
Off Turbo control is off
Manual

Turbo control uses settings from U64.

Settings CANNOT be altered with registers.

U64 Turbo Registers

Turbo control uses settings from U64.

Settings CAN be altered with registers.

See Turbo Control registers.

TurboEnable Bit

Turbo control uses settings from U64.

Settings CAN be altered with registers.

See Turbo Control registers.

CPU Speed

Turbo cpu speed
Set CPU Speed.

Default C64/U64 speed: 1MHz (1x)
Maximum speed: 48MHz (48x)

Badline Timing

Turbo badline timing
Enabled/disable badline timing.

Turn off badlines to get more CPU cycles.
This can be controlled with registers programmable. See Turbo Control registers.

SuperCPU Detect ($D0BC)

SuperCPU Mode Detect Register

Turbo Control registers

Address Description
53297/$D031

U64 Turbo Control

This register is only available when the Turbo Mode selector is set to ‘U64 Turbo Registers’ or ‘Turbo Enable Bit’. Otherwise it simply reads $FF.

  • bit 0-3: CPU Speed (index)
  • bit 7: Badline timing, 0 = Enabled, 1 = Disabled

CPU Speed (index)

  • 0 = 1 MHz
  • 1 = 2 MHz
  • 2 = 3 MHz
  • 3 = 4 MHz
  • 4 = 5 MHz
  • 5 = 6 MHz
  • 6 = 8 MHz
  • 7 = 10 MHz
  • 8 = 12 MHz
  • 9 = 14 MHz
  • 10 = 16 MHz
  • 11 = 20 MHz
  • 12 = 24 MHz
  • 13 = 32 MHz
  • 14 = 40 MHz
  • 15 = 48 MHz
53296/$D030

Turbo Enable Bit

This register is only available when the Turbo Mode selector is set to ‘Turbo Enable Bit’. Otherwise it simply reads $FF.

  • bit 0 (Write):

    0 = 1 MHz + Badlines

    1 = Use settings from menu

  • bit 0 (Read):

    0 = Turbo Off

    1 = Turbo On

53370/$D07A

SuperCPU compatible enable/disable registers

This register is only available when the Turbo Mode selector is set to ‘U64 Turbo Registers’ or ‘Turbo Enable Bit’. This register is write only

  • Software Speed Select - Normal

More information: https://www.c64-wiki.com/wiki/SuperCPU

53371/$D07B

SuperCPU compatible enable/disable registers

This register is only available when the Turbo Mode selector is set to ‘U64 Turbo Registers’ or ‘Turbo Enable Bit’. This register is write only

  • Software Speed Select - Turbo (20 MHz)($079)

More information: https://www.c64-wiki.com/wiki/SuperCPU

53436/$D0BC

SuperCPU Detect ($D0BC)

  • SuperCPU Mode Detect Register

This register is only available when it is separately enabled. This register is read only

More information: https://www.c64-wiki.com/wiki/SuperCPU

Applies to: Ultimate 64

*) Setting are only available on the Ultimate 64, firmware >= 1.33*