WikiTI - User contributions [en]

83:Ports:15

2005-04-03T08:25:31Z

195.56.94.233:

== Synopsis ==
'''Port Number:''' 15h

'''Function:''' Unknown

=== Read Values ===
Always 254.

=== Write Values ===
This port doesn't seem to do anything.

[[Category:83:Ports:By Address|15 - Unknown port]]
[[Category:83:Ports:By Name|Unknown port]]

83:Ports:03

2005-04-03T08:18:17Z

195.56.94.233: if interrupts are disabled, any value between 0 and 15 can be read

[[Category:83:Ports:By_Address|03 - Interrupt Control]] [[Category:83:Ports:By_Name|Interrupt Control]]
== Synopsis ==
'''Port Number:''' 03h

'''Function:''' Interrupt Control Port

This port controls all devices that can generate interrupts.

=== Read Values ===
* Bit 0: Set if the ON key generated an interrupt.
* Bit 1: Set if the first hardware timer generated an interrupt.
* Bit 2: Set if the second hardware timer generated an interrupt.
* Bit 3: Reset if the ON key is being pressed; set otherwise.
* Bit 4-7: Unused.

=== Write Values ===
* Bit 0: Set 0 to disable ON key interrupts and to acknowledge an ON key interrupt. Set 1 to enable ON key interrupts.
* Bit 1: Set 0 to disable interrupts from the first timer and to acknowledge an interrupt from the first timer. Set 1 to enable interrupts from the first timer.
* Bit 2: Set 0 to disable interrupts from the second timer and to acknowledge an interrupt from the second timer. Set 1 to enable interrupts from the second timer.
* Bit 3: Set 0 to turn off the LCD. Set 1 to enable the LCD.
* Bit 4-7: Unused.

== Comments ==
* You need to acknowledge interrupts. Otherwise a new interrupt will be generated directly after you enable interrupts again with EI. Because that disables that particular interrupt at the same time, you may have to write a second value to this port to reenable it.

83:Ports:04

2005-04-03T08:14:44Z

195.56.94.233:

[[Category:83:Ports:By_Address|04 - Timer Interrupt Frequency / Memory Map]] [[Category:83:Ports:By_Name|Timer Interrupt Frequency / Memory Map]]
== Synopsis ==
'''Port Number:''' 04h

'''Function:''' Timer Interrupt Frequency and Memory Map Control

This port controls the frequency of the hardware timer and the memory map mode.

=== Read Values ===
This is a mirror of the link port.

=== Write Values ===
* Bit 0 reset to select memory map mode 0. In mode 0 the RAM and ROM is mapped to CPU memory as follows:
** Address 0000h ~ 3FFFh: ROM Page 0
** Address 4000h ~ 7FFFh: Swappable (Page selected in [[83:Ports:00]]/[[83:Ports:02]])
** Address 8000h ~ BFFFh: RAM Page 1
** Address C000h ~ FFFFh: RAM Page 0
* Bit 0 set to select memory map mode 1. In mode 1 the RAM and ROM is mapped to CPU memory as follows:
** Address 0000h ~ 3FFFh: ROM Page 0
** Address 4000h ~ 7FFFh: RAM Page 0
** Address 8000h ~ BFFFh: Swappable (Page selected in [[83:Ports:00]]/[[83:Ports:02]])
** Address C000h ~ FFFFh: RAM Page 1
* Bits 1 and 2 control the hardware timer frequency. Setting both 0 sets the timer to the fastest speed, and both 1 is the slowest speed. The normal speed is with both bits 1.
* Bit 3: Unused? Always 0.
* Bit 4: Timer frequency multiplier; when this bit is set, all the times are multiplied by 90% (i. e. it's 11.1% faster) compared to when it's reset.
* Bit 5-7: Unknown, but definitely used.

== Comments ==
The calculator uses mode 0 for normal operation. If you change the memory map mode be sure to change it back before returning control.

To calculate the resulting timer frequency you can use the following formula:

freq = 1800 * ((out_value & 0x10) ? 1.0 : 0.9) / (3 + ((out_value & 0x06) << 1))

83:Ports:04

2005-04-03T08:12:26Z

195.56.94.233:

83:Ports:04

2005-04-03T08:12:05Z

195.56.94.233:

[[Category:83:Ports:By_Address|04 - Timer Interrupt Frequency / Memory Map]] [[Category:83:Ports:By_Name|Timer Interrupt Frequency / Memory Map]]
== Synopsis ==
'''Port Number:''' 04h

'''Function:''' Timer Interrupt Frequency and Memory Map Control

This port controls the frequency of the hardware timer and the memory map mode.

=== Read Values ===
This is a mirror of the link port.

=== Write Values ===
* Bit 0 reset to select memory map mode 0. In mode 0 the RAM and ROM is mapped to CPU memory as follows:
** Address 0000h ~ 3FFFh: ROM Page 0
** Address 4000h ~ 7FFFh: Swappable (Page selected in [[83:Ports:00]]/[[83:Ports:02]])
** Address 8000h ~ BFFFh: RAM Page 1
** Address C000h ~ FFFFh: RAM Page 0
* Bit 0 set to select memory map mode 1. In mode 1 the RAM and ROM is mapped to CPU memory as follows:
** Address 0000h ~ 3FFFh: ROM Page 0
** Address 4000h ~ 7FFFh: RAM Page 0
** Address 8000h ~ BFFFh: Swappable (Page selected in [[83:Ports:00]]/[[83:Ports:02]])
** Address C000h ~ FFFFh: RAM Page 1
* Bits 1 and 2 control the hardware timer frequency. Setting both 0 sets the timer to the fastest speed, and both 1 is the slowest speed. The normal speed is with both bits 1.
* Bit 3: Unused? Always 0.
* Bit 4: Timer frequency multiplier; when this bit is set, all the times are multiplied by 90% (i. e. it's 11.1% faster) compared to when it's reset.
* Bit 5-7: Unknown, but definitely used.

== Comments ==
The calculator uses mode 0 for normal operation. If you change the memory map mode be sure to change it back before returning control.

To calculate resulting timer frequency you can use the following formula:

freq = 1800 * ((out_value & 0x10) ? 1.0 : 0.9) / (3 + ((out_value & 0x06) << 1)) / 6000000