CPU Speed control: Difference between revisions
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''Acceleration'', or ''Turbo mode'', allows the Next to run at faster clock speeds than a standard Spectrum. | ''Acceleration'', or ''Turbo mode'', allows the Next to run at faster clock speeds than a standard Spectrum. | ||
Acceleration is enabled via {{NextRegNo|$06}} and configured via {{NextRegNo|$07}}, or via a user control. There are | Acceleration is enabled via {{NextRegNo|$06}} and configured via {{NextRegNo|$07}}, or via a user control. There are three (0..2) potential settings: | ||
* Turbo off, or turbo on and $07 set to #00: 3.5 Mhz (standard clock). | * Turbo off, or turbo on and $07 set to #00: 3.5 Mhz (standard clock). | ||
* Turbo on, $07 set to #01: 7 Mhz (x2). (Standard for [[Reference machines|Pentagon]]). | * Turbo on, $07 set to #01: 7 Mhz (x2). (Standard for [[Reference machines|Pentagon]]). | ||
* Turbo on, $07 set to #10: 14 Mhz. (x4) | * Turbo on, $07 set to #10: 14 Mhz. (x4) Some features, such as [[Layer 2]] (vertically visible pixel area) and shadow-VRAM of ZX128 (whole pixel area), will automatically throttle down to 7MHz while specified areas of display are sent to the video signal. | ||
* Turbo on, $07 set to #11: 28 Mhz. (x8) | * Turbo on, $07 set to #11: 28 Mhz. (x8) - this mode is removed for the moment, due to HW limitations (the system was not stable enough at 28MHz). | ||
Revision as of 11:08, 27 January 2019
Acceleration, or Turbo mode, allows the Next to run at faster clock speeds than a standard Spectrum.
Acceleration is enabled via {{#ask: TBRegisterNumber::$06 }} ($06) and configured via {{#ask: TBRegisterNumber::$07 }} ($07), or via a user control. There are three (0..2) potential settings:
- Turbo off, or turbo on and $07 set to #00: 3.5 Mhz (standard clock).
- Turbo on, $07 set to #01: 7 Mhz (x2). (Standard for Pentagon).
- Turbo on, $07 set to #10: 14 Mhz. (x4) Some features, such as Layer 2 (vertically visible pixel area) and shadow-VRAM of ZX128 (whole pixel area), will automatically throttle down to 7MHz while specified areas of display are sent to the video signal.
- Turbo on, $07 set to #11: 28 Mhz. (x8) - this mode is removed for the moment, due to HW limitations (the system was not stable enough at 28MHz).