WikiTI - User contributions [en]

83Plus:Ports:00

2005-03-27T12:13:05Z

81.69.25.24: /* Data transfer */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
* [http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
* [http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a,0 ; Set both lines high
out (0),a

ld a,2 ; Set tip high, ring low
out (0),a

ld a,1 ; Set tip low, ring high
out (0),a

ld a,3 ; Set both low
out (0),a</pre>

=== Receiving/Reading ===
<pre>in a,(0) ; Get the link port value

bit 0,a ; Check tip
jr z,tip_low
jr nz,tip_high

bit 1,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

83Plus:Ports:00

2005-03-27T12:12:15Z

81.69.25.24: /* Receiving/Reading */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a,0 ; Set both lines high
out (0),a

ld a,2 ; Set tip high, ring low
out (0),a

ld a,1 ; Set tip low, ring high
out (0),a

ld a,3 ; Set both low
out (0),a</pre>

=== Receiving/Reading ===
<pre>in a,(0) ; Get the link port value

bit 0,a ; Check tip
jr z,tip_low
jr nz,tip_high

bit 1,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

83Plus:Ports:00

2005-03-27T12:11:54Z

81.69.25.24: /* Receiving/Reading */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a,0 ; Set both lines high
out (0),a

ld a,2 ; Set tip high, ring low
out (0),a

ld a,1 ; Set tip low, ring high
out (0),a

ld a,3 ; Set both low
out (0),a</pre>

=== Receiving/Reading ===
<pre>in a,(0) ; Get the link port value
bit 0,a ; Check tip
jr z,tip_low
jr nz,tip_high
bit 1,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

83Plus:Ports:00

2005-03-27T12:11:30Z

81.69.25.24: /* Sending/Setting */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a,0 ; Set both lines high
out (0),a

ld a,2 ; Set tip high, ring low
out (0),a

ld a,1 ; Set tip low, ring high
out (0),a

ld a,3 ; Set both low
out (0),a</pre>

=== Receiving/Reading ===
<pre>in a,(0) ; Get the link port value
bit 0,a ; Check tip
jr z,tip_low
jr nz,tip_high
bit 1,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

83Plus:Ports:00

2005-03-27T12:10:52Z

81.69.25.24: /* Sending/Setting */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a, 0 ; Set both lines high
out (0), a

ld a, 2 ; Set tip high, ring low
out (0), a

ld a, 1 ; Set tip low, ring high
out (0), a

ld a, 3 ; Set both low
out (0), a</pre>

=== Receiving/Reading ===
<pre>in a,(0) ; Get the link port value
bit 0,a ; Check tip
jr z,tip_low
jr nz,tip_high
bit 1,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

83Plus:Ports:00

2005-03-27T12:09:05Z

81.69.25.24: /* Receiving/Reading */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a, 0 ;Release both lines.
out (0), a
in a, (0) ;03h
ld a, 2 ;Hold bit 1 low.
out (0), a
in a, (0) ;21h
ld a, 1 ;Relase bit 1, hold bit 0 low.
out (0), a
in a, (0) ;12h
ld a, 3 ;Hold bit 1 low. Bit 0 stays low.
out (0), a
in a, (0) ;30h
ld a, 0 ;Release both lines.
out (0), a</pre>

=== Receiving/Reading ===
<pre>in a,(0) ; Get the link port value
bit 0,a ; Check tip
jr z,tip_low
jr nz,tip_high
bit 1,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

83Plus:Ports:00

2005-03-27T12:07:56Z

81.69.25.24: /* Receiving/Reading */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a, 0 ;Release both lines.
out (0), a
in a, (0) ;03h
ld a, 2 ;Hold bit 1 low.
out (0), a
in a, (0) ;21h
ld a, 1 ;Relase bit 1, hold bit 0 low.
out (0), a
in a, (0) ;12h
ld a, 3 ;Hold bit 1 low. Bit 0 stays low.
out (0), a
in a, (0) ;30h
ld a, 0 ;Release both lines.
out (0), a</pre>

=== Receiving/Reading ===
<pre>in a,(0)
bit 0,a
jr z,tip_low
bit 1,a
jr z,tip_high</pre>

83Plus:Ports:00

2005-03-27T12:06:34Z

81.69.25.24: /* Example */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==

=== Sending/Setting ===
<pre>ld a, 0 ;Release both lines.
out (0), a
in a, (0) ;03h
ld a, 2 ;Hold bit 1 low.
out (0), a
in a, (0) ;21h
ld a, 1 ;Relase bit 1, hold bit 0 low.
out (0), a
in a, (0) ;12h
ld a, 3 ;Hold bit 1 low. Bit 0 stays low.
out (0), a
in a, (0) ;30h
ld a, 0 ;Release both lines.
out (0), a</pre>

=== Receiving/Reading ===
<pre>in a,(0)
bit 0,tip_low
bit 1,tip_high</pre>

83Plus:Ports:00

2005-03-27T12:00:46Z

81.69.25.24: /* Credits and Contributions */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==
<nowiki>ld a, 0 ;Release both lines.
out (0), a
in a, (0) ;03h
ld a, 2 ;Hold bit 1 low.
out (0), a
in a, (0) ;21h
ld a, 1 ;Relase bit 1, hold bit 0 low.
out (0), a
in a, (0) ;12h
ld a, 3 ;Hold bit 1 low. Bit 0 stays low.
out (0), a
in a, (0) ;30h
ld a, 0 ;Release both lines.
out (0), a</nowiki>

83Plus:Ports:00

2005-03-27T11:59:11Z

81.69.25.24: /* Comments */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==

=== Bit 2 ===
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

=== Ti-OS interference ===
One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background. When two calculators are connected and one pulls a line low, the other calculator will respond by pulling the other line low to acknowledge that it has received a bit. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :). It's unclear if this is only when the other calculator is in the homescreen, or if it is part of the default interrupt routine at $0038.

=== Data transfer ===
Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==
<nowiki>ld a, 0 ;Release both lines.
out (0), a
in a, (0) ;03h
ld a, 2 ;Hold bit 1 low.
out (0), a
in a, (0) ;21h
ld a, 1 ;Relase bit 1, hold bit 0 low.
out (0), a
in a, (0) ;12h
ld a, 3 ;Hold bit 1 low. Bit 0 stays low.
out (0), a
in a, (0) ;30h
ld a, 0 ;Release both lines.
out (0), a</nowiki>

== Credits and Contributions ==
* '''/dev/urandom:''' Because of your randomness, this project is possible.

83Plus:Ports:00

2005-03-27T11:43:37Z

81.69.25.24: /* Comments */

== Synopsis ==
'''Port Number:''' 00h

This port controls the calculator's serial link port (the standard link port present on the 83+, 83+ SE, 84+ and 84+ SE - do not confuse this with the 84+/84+SE's USB link port).

=== Read Values ===
* Bit 0 and 1: The low 2 bits indicate the state of the link port's two lines. A 1 bit indicates a high line, and a 0 bit indicates a low line. When idle (no transfer in progress, no cable plugged in, etc), both lines are usually high (1). When a cable is connected on both ends, a line reads high if and only if both ends have set the line high. The line will read low if either calculator sets it low.
* Bit 5 and 6: Bits 5 and 6 indicate which lines are pulled low by the calculator (unlike bits 0 and 1 they are not influenced by the other calculator). A 1 bit indicates your calculator is holding the line low. A 0 bit indicates your calculator is not holding the line low. (When both calculators have a 0 bit here, the corresponding line will read 1.) In other words, these bits reflect bits 0 and 1 from the most recent write to this port.
* Bit 2: I have absolutely no idea what this means or does...

=== Write Values ===
* Bit 0 and 1: The low 2 bits indicate what state the lines should be put into. A 1 bit will pull the line low. A 0 bit will stop holding the line low (allowing it to go high if the other calculator is not holding it low).
* Bit 2: I have absolutely no idea what this means or does, except that any change of this bit causes both lines to be released, and writing with this bit set causes bit 2 to read 1, and the next write causes it to read 0 and both lines are released.

== Comments ==
As mentioned bit 2's effect is unknown. An example of it's behavior follows:
<nowiki>Start, read 03.
Write 02, read 01.
Write 07, read 07.
Write 07, read 03.
Write 07, read 07.
Write 00, read 03.
Write 09, read 07.
Write 01, read 03.</nowiki>

Note: Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, and [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol].

Other useful information on linking in general: 
[http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide] 
[http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]

== Example ==
<nowiki>ld a, 0 ;Release both lines.
out (0), a
in a, (0) ;03h
ld a, 2 ;Hold bit 1 low.
out (0), a
in a, (0) ;21h
ld a, 1 ;Relase bit 1, hold bit 0 low.
out (0), a
in a, (0) ;12h
ld a, 3 ;Hold bit 1 low. Bit 0 stays low.
out (0), a
in a, (0) ;30h
ld a, 0 ;Release both lines.
out (0), a</nowiki>

== Credits and Contributions ==
* '''/dev/urandom:''' Because of your randomness, this project is possible.