83Plus:Ports:04 - Revision history

Fghsgh: make it clear that bits 5-7 do not actually signify an interrupt

2020-03-15T16:21:47Z

make it clear that bits 5-7 do not actually signify an interrupt

2014-12-17T06:53:09Z

Not a question anymore.

2013-09-11T06:25:41Z

2013-09-11T06:24:42Z

2013-09-11T06:21:23Z

2013-08-09T01:43:58Z

‎Write Values: fix link

2013-08-09T01:42:25Z

add battery checking information for the TI-84+CSE

2013-03-15T05:08:44Z

Resolved bits 3-5.

2013-03-15T05:07:53Z

Resolved bits 6&7.

2011-09-17T17:37:24Z

‎Write Values

← Older revision		Revision as of 16:21, 15 March 2020
Line 75:		Line 75:

	Interrupt timers may not be independent of the CPU speed for the 83+. However on the 83+SE, 84+ and 84+SE the standard timers are based on the crystal timer. Timer1 fires at 32768/(64+(80*i))hz, where i is bit 1 and 2 set in port 4, making it 0<=i<=3.		Interrupt timers may not be independent of the CPU speed for the 83+. However on the 83+SE, 84+ and 84+SE the standard timers are based on the crystal timer. Timer1 fires at 32768/(64+(80*i))hz, where i is bit 1 and 2 set in port 4, making it 0<=i<=3.
		+
		+	Bits 5-7 will also read 1 if the timer's interrupts are disabled and the timer has expired.

	== Example ==		== Example ==

@@ Line 66: / Line 66: @@
 ** '''83+ Basic''': No function
 ** '''Everything else''': These two bits are used to determine the battery state. They act as a 2-bit number and the higher it is, the higher the voltage cutoff for bit 0 of [[83Plus:Ports:02|Port 2]]. Unless you are trying to determine battery state, these two bits should be zero.
-*** '''TI-83+SE''': Only bit 7 has any effect?
+*** '''TI-83+SE''': Only has one bit, bit 7; the second bit was added for the 84-series.
 *** '''TI-84+/SE''': Numbers 00 and 10 are not currently used. 01 measures if the batteries are removed (0v). 11 measures if the main batteries are present but "low".
 *** '''TI-84+CSE''': Based on the OS battery check routine, these two bits are in reverse order; that is, bit 6 is ''more'' significant than bit 7. (This probably also applies to the B&W models.) The routine always delays between changing these bits and checking bit 0 of [[83Plus:Ports:02|port 2]]. Also, for each check value, it writes 06 (i.e. resets the port) and then writes the value it intends to write. It writes, in order, 06, 86, 46, C6. If bit 0 of port 2 is reset after any of those writes, it returns 0 through 3, respectively; if bit 0 of port 2 remains set after all of those writes, it returns 4. Bit 7 of [[83Plus:Ports:3A|port 3A]] is also related; that bit is normally kept reset, but is set for the duration of the test routine.

@@ Line 5: / Line 5: @@
 '''Function:''' Interrupting Device Identification and Memory Map Control
-''See also: [[83Plus:Interrupts]]''
+''See also: [[83Plus:Interrupts]], [[83Plus:Memory_Mapping]]''
 This port serves two purposes. When read it indicates the device that triggered an interrupt. When written it sets the memory map mode and hardware timer speed. When an interrupt is triggered, it should be cleared by reseting the corresponding bit in [[83Plus:Ports:03|port 3]].  Otherwise, it will continuously call the interrupt code once interrupts are reenabled with ei.

@@ Line 5: / Line 5: @@
 '''Function:''' Interrupting Device Identification and Memory Map Control
-'''See also:''' [[83Plus:Interrupts]]
+''See also: [[83Plus:Interrupts]]''
 This port serves two purposes. When read it indicates the device that triggered an interrupt. When written it sets the memory map mode and hardware timer speed. When an interrupt is triggered, it should be cleared by reseting the corresponding bit in [[83Plus:Ports:03|port 3]].  Otherwise, it will continuously call the interrupt code once interrupts are reenabled with ei.

← Older revision		Revision as of 06:21, 11 September 2013
Line 4:		Line 4:

	'''Function:''' Interrupting Device Identification and Memory Map Control		'''Function:''' Interrupting Device Identification and Memory Map Control
		+
		+	'''See also:''' [[83Plus:Interrupts]]

	This port serves two purposes. When read it indicates the device that triggered an interrupt. When written it sets the memory map mode and hardware timer speed. When an interrupt is triggered, it should be cleared by reseting the corresponding bit in [[83Plus:Ports:03\|port 3]]. Otherwise, it will continuously call the interrupt code once interrupts are reenabled with ei.		This port serves two purposes. When read it indicates the device that triggered an interrupt. When written it sets the memory map mode and hardware timer speed. When an interrupt is triggered, it should be cleared by reseting the corresponding bit in [[83Plus:Ports:03\|port 3]]. Otherwise, it will continuously call the interrupt code once interrupts are reenabled with ei.

@@ Line 61: / Line 61: @@
 |}
 * Bits 3~5: Unused.
-* Bits 6 and 7: On everything but the 83+, these two bits are used to determine the battery state. They act as a 2-bit number and the higher it is, the higher the voltage cutoff for bit 0 of [[83Plus:Ports:02|Port 2]]. Unless you are trying to determine battery state, these two bits should be zero. Numbers 00 and 10 are not currently used. 01 measures if the batteries are removed (0v). 11 measures if the main batteries are present but "low".
+* Bits 6 and 7:
 == 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.
+The calculator uses memory mapping mode 0 for normal operation. If you change the memory map mode be sure to change it back before returning control.
 Also, do not switch from mode 0 to mode 1 inside the 4000h ~ 7FFFh range unless you've changed the RAM Execution Limits with ports [[83Plus:Ports:25|25]] and [[83Plus:Ports:26|26]].  This is because switching modes in this manner will start executing on RAM page 0, which will crash under normal conditions.

@@ Line 60: / Line 60: @@
 |118||107.79||236||215.58||353||323.37
 |}
-* Bits 3~5: No apparent effect
+* Bits 3~5: Unused.
 * Bits 6 and 7: On everything but the 83+, these two bits are used to determine the battery state. They act as a 2-bit number and the higher it is, the higher the voltage cutoff for bit 0 of [[83Plus:Ports:02|Port 2]]. Unless you are trying to determine battery state, these two bits should be zero. Numbers 00 and 10 are not currently used. 01 measures if the batteries are removed (0v). 11 measures if the main batteries are present but "low".