Timing: Difference between revisions
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== Clocks == | == Clocks == | ||
The WonderSwan is clocked with a master clock of approximately 12288000 Hz (= 12.288 MHz). | The WonderSwan is clocked with a ''master clock'' of approximately 12288000 Hz (= 12.288 MHz). | ||
This clock is split into four internal memory access quadrants, running at 3072000 Hz (= 3.072 MHz) each. Three of those are used by the console in "mono" mode: | This clock is split into four internal memory access quadrants, running at 3072000 Hz (= 3.072 MHz) each. Three of those are used by the console in "mono" mode: | ||
* [[CPU|NEC V30MZ]] - referred to as the ''CPU clock'', | |||
* [[Display]], | |||
* [[Sound]]. | |||
On the WonderSwan Color, the fourth quadrant is used to handle color palette reads during display drawing. | |||
== Display == | Only the CPU quadrant can access the cartridge bus; this means that [[DMA]] necessarily stalls the CPU. | ||
In addition, a separate 384000 Hz (3072000 / 8) ''cartridge clock'' is provided on one of the cartridge pins. | |||
== Display timing == | |||
By default, a WonderSwan frame consists of 159 lines, 144 of which are visible. Each line consists of 256 clock cycles, of which 224 are used to draw a pixel at a time. This leads to a total duration of 40704 clock cycles per frame, for an effective default refresh rate of approximately 75.472 Hz. | By default, a WonderSwan frame consists of 159 lines, 144 of which are visible. Each line consists of 256 clock cycles, of which 224 are used to draw a pixel at a time. This leads to a total duration of 40704 clock cycles per frame, for an effective default refresh rate of approximately 75.472 Hz. | ||
Vertical blanks are always triggered on line 144; if the display is set to be shorter than 144 lines, vertical blank interrupts will never be triggered. | Vertical blanks are always triggered on line 144; if the display is set to be shorter than 144 lines, vertical blank interrupts will never be triggered. | ||
TODO: back/front porches, etc. | |||
== Frame timing == | |||
The details of per-line and per-frame timing are available in a table on the [[Frame timing]] page. | |||
Latest revision as of 18:20, 22 August 2023
Clocks
The WonderSwan is clocked with a master clock of approximately 12288000 Hz (= 12.288 MHz).
This clock is split into four internal memory access quadrants, running at 3072000 Hz (= 3.072 MHz) each. Three of those are used by the console in "mono" mode:
On the WonderSwan Color, the fourth quadrant is used to handle color palette reads during display drawing.
Only the CPU quadrant can access the cartridge bus; this means that DMA necessarily stalls the CPU.
In addition, a separate 384000 Hz (3072000 / 8) cartridge clock is provided on one of the cartridge pins.
Display timing
By default, a WonderSwan frame consists of 159 lines, 144 of which are visible. Each line consists of 256 clock cycles, of which 224 are used to draw a pixel at a time. This leads to a total duration of 40704 clock cycles per frame, for an effective default refresh rate of approximately 75.472 Hz.
Vertical blanks are always triggered on line 144; if the display is set to be shorter than 144 lines, vertical blank interrupts will never be triggered.
TODO: back/front porches, etc.
Frame timing
The details of per-line and per-frame timing are available in a table on the Frame timing page.
