83:Ports:00 - Revision history

Timendus: /* Data transfer */

2007-07-01T23:14:22Z

‎Data transfer

Timendus: /* Ti-OS interference */

2006-04-27T14:30:30Z

‎Ti-OS interference

Timendus: /* Data transfer */

2005-04-28T10:26:59Z

‎Data transfer

Kalimero at 13:40, 30 March 2005

2005-03-30T13:40:54Z

195.56.94.159: /* Read Values */

2005-03-30T10:24:41Z

‎Read Values

195.56.94.159 at 09:53, 30 March 2005

2005-03-30T09:53:41Z

FloppusMaximus at 05:03, 30 March 2005

2005-03-30T05:03:13Z

Dan Englender: Added categories and function

2005-03-28T18:36:56Z

Added categories and function

Timendus: /* Write Values */

2005-03-27T17:35:23Z

‎Write Values

Timendus at 17:34, 27 March 2005

2005-03-27T17:34:32Z

New page

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

This port controls the calculator's serial link port.

=== Read Values ===
* Bit 2 and 3: These two 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.

=== 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).
* Bits 4, 6 and 7: These bits should be high for unknown reasons
 

== Comments ==

=== 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,$D0 ; Set both lines high
out (0),a

ld a,$D2 ; Set tip high, ring low
out (0),a

ld a,$D1 ; Set tip low, ring high
out (0),a

ld a,$D3 ; Set both low
out (0),a</pre>

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

bit 2,a ; Check tip
jr z,tip_low
jr nz,tip_high

bit 3,a ; Check ring
jr z,ring_low
jr nz,ring_high</pre>

@@ Line 10: / Line 10: @@
 * Bit 0 and 1: The inverse of the values output to the link port.
 * Bit 2 and 3: These two 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 4: Bit 3 of hte current ROM page
+* Bit 4: Bit 3 of the current ROM page
 * Bit 5-7: Zero

@@ Line 1: / Line 1: @@
-[[Category:83:Ports:By_Address|00 - Link]]
+[[Category:83:Ports:By_Address|00 - Link]] [[Category:83:Ports:By_Name|Link]]
 [[Category:83:Ports:By_Name|Link]]
 == Synopsis ==
 '''Port Number:''' 00h

@@ Line 24: / Line 24: @@
 === 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].
+Transferring an entire byte requires you to implement some form of protocol. Examples include TI's official linking protocol, [http://www.ticalc.org/archives/files/fileinfo/277/27718.html Michael Vincent's TachyonLink protocol] and [http://bell.timendus.com/ Timendus' Bell library].
 Other useful information on linking in general:
@@ Line 30: / Line 30: @@
 *  [http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]
 *  [http://www.ticalc.org/archives/files/fileinfo/242/24244.html All about the Ti-86 link port]
 == Example ==

@@ Line 21: / Line 21: @@
 === 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.
+One thing to keep in mind when writing link port related software is that the Ti-OS checks for silent transfers in the background of input routines. 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. Even when the other calculator is running an assembly program that uses the getkey romcall. This phenomenon is known to cause severe headaches for programmers who attempt to write synchronization routines :).
 === Data transfer ===

@@ Line 3: / Line 3: @@
 '''Port Number:''' 00h
-'''Function:''' Link
+'''Function:''' Link port and Rom page swapping
-This port controls the calculator's serial link port.
+This port has two functions. It controls the calculator's serial link port and together with [[83:Ports:02]], the ROM page that is swapped into 4000h-7FFFh.
 === Read Values ===
 * Bit 0 and 1: The inverse of the values output to the link port.
 * Bit 2 and 3: These two 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 4: Bit 3 of the current ROM page
+* Bit 4: Bit 3 of the current ROM page. See also [[83:Ports:02]].
 * Bit 5-7: Zero
 === 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 4: Bit 3 of the current ROM page
+* Bit 4: Bit 3 of the current ROM page. See also [[83:Ports:02]].
-* Bit 6 and 7: These bits should be 1 for unknown reasons
+* Bit 6 and 7: These bits should be 1 for unknown reasons.
-<br>
 == Comments ==
@@ Line 27: / Line 26: @@
 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].
-<p>Other useful information on linking in general:<br>
+Other useful information on linking in general:
-* [http://www.ticalc.org/archives/files/fileinfo/247/24750.html TI Link Protocol & File Format Guide]<br>
+*  [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]
+*  [http://www.ticalc.org/archives/files/fileinfo/294/29418.html Ti-83 Link Port Tutorial]
-<br>
 == Example ==
 === Sending/Setting ===
-<pre>ld a,$D0     ; Set both lines high
+ <nowiki>ld a,$D0     ; Set both lines high
 out (0),a
@@ Line 45: / Line 43: @@
 ld a,$D3     ; Set both low
-out (0),a</pre>
+out (0),a</nowiki>
 === Receiving/Reading ===
-<pre>in a,(0)        ; Get the link port value
+ <nowiki>in a,(0)        ; Get the link port value
 bit 2,a         ; Check tip
@@ Line 56: / Line 54: @@
 bit 3,a         ; Check ring
 jr z,ring_low
-jr nz,ring_high</pre>
+jr nz,ring_high</nowiki>

@@ Line 9: / Line 9: @@
 === 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).
-* Bits 4, 6 and 7: These bits should be high for unknown reasons
+* Bits 4, 6 and 7: These bits should be 1 for unknown reasons
 <br>