In order to run code on the Ultimate64 using the 48 Mhz mode a set of requirements must be met, see Turbo Mode control registers documentation
Ultimate64
- Firmware version 1.33 or higher
- Turbo Mode set to
Turbo Enable Bit
https://github.com/markusC64/1541ultimate2/releases/tag/tools-v1.2.1
The turbo mode can be controlled by setting values at specific addresses.
This register is only available when the Turbo Mode selector is set to ‘Turbo Enable Bit’. Otherwise it simply reads $FF.
| Value | Details |
|---|---|
| bit 0 (Write): | 0 = 1 MHz + Badlines 1 = Use settings from menu |
| bit 0 (Read): | 0 = Turbo Off 1 = Turbo On |
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.
| Value | Details |
|---|---|
| bit 0-3: | 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 |
| bit 7: | Badline timing 0 = Enabled, 1 = Disabled |
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
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)
- SuperCPU Mode Detect Register
This register is only available when it is separately enabled. This register is read only.