WikiTI - User contributions [en]

83:Ports:14

2005-03-30T10:28:51Z

195.56.94.159:

[[Category:83:Ports:By_Address|14 - Battery status]] [[Category:83:Ports:By_Name|Battery status]]
== Synopsis ==
'''Port Number:''' 14h

'''Function:''' Battery status checking

This is a read-only port indicating battery status. It also acts as a mirror of the link port on the rest of the bits.

=== Read Values ===
* Bit 0: Reads 1 if batteries are high; 0 if they are low.
* Bits 1 to 7: Mirror of the [[83:Ports:00|link port]].

83:Ports:02

2005-03-30T10:25:48Z

195.56.94.159:

== Synopsis ==
'''Port Number:''' 02h

'''Function:''' ROM and RAM Pager

This port controls what page is swapped into the 4000h to 7FFFh range.

=== Read Values ===
Always the last value output is read back.

=== Write Values ===
* Bits 0 to 2: The lower 3 bits of the desired ROM page (bit 3 can be set through bit 4 of the [[83:Ports:00|link port]])
* Bit 3: Must be 1, otherwise the the calculator crashes
* Bit 4: 0 - the specified ROM page is swapped in, 1 - the RAM page specified by bit 0 swapped in (0 causes it to mirror the page at C000h, 1 mirrors the page at 8000h)
* Bit 5: Unknown, harmless
* Bit 6: Unknown, harmless
* Bit 7: Must be 1, otherwise the the calculator crashes

== Credits and Contributions ==
* created by CoBB

[[Category:83:Ports:By Address|02 - ROM and RAM pager]]
[[Category:83:Ports:By Name|ROM and RAM pager]]

83:Ports:00

2005-03-30T10:24:41Z

195.56.94.159: /* Read Values */

[[Category:83:Ports:By_Address|00 - Link]] [[Category:83:Ports:By_Name|Link]]
== Synopsis ==
'''Port Number:''' 00h

'''Function:''' Link

This port controls the calculator's serial link port.

=== 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 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 6 and 7: These bits should be 1 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>

83:Ports:02

2005-03-30T10:23:55Z

195.56.94.159:

83:Ports:Mirrors

2005-03-30T10:14:55Z

195.56.94.159:

== General ==
When addressing the ports of the 83, only bits 0, 1, 2 and 4 make a difference, so every port has at least 15 mirrors by altering bits 3, 5, 6 or 7 (e. g. LCD status is available at port 38 as well). These variations are not listed below. All addresses are hexadecimal.

== Input ports ==
* [[83:Ports:00|Link and pager]]: 00, 04
* [[83:Ports:01|Keyboard status]]: 01, 05
* [[83:Ports:02|Pager]]: 02, 06, 16
* [[83:Ports:03|Interrupt status]]: 03, 07, 17
* [[83:Ports:10|LCD status]]: 10, 12
* [[83:Ports:11|LCD data]]: 11, 13
* [[83:Ports:14|Battery and link status]]: 14
* [[83:Ports:15|Unknown]]: 15

== Output ports ==
* [[83:Ports:00|Link and pager]]: 00
* [[83:Ports:01|Keyboard mask]]: 01
* [[83:Ports:02|Pager]]: 02
* [[83:Ports:03|Interrupt mask]]: 03
* [[83:Ports:04|Timer frequency]]: 04
* [[83:Ports:10|LCD command]]: 10, 12
* [[83:Ports:11|LCD data]]: 11, 13

[[Category:83:Ports|Mirrors]]

83:Ports:00

2005-03-30T09:53:41Z

195.56.94.159:

[[Category:83:Ports:By_Address|00 - Link]] [[Category:83:Ports:By_Name|Link]]
== Synopsis ==
'''Port Number:''' 00h

'''Function:''' Link

This port controls the calculator's serial link port.

=== 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 hte current ROM page
* 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 6 and 7: These bits should be 1 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>

83:Ports:14

2005-03-30T09:49:45Z

195.56.94.159:

[[Category:83:Ports:By_Address|14 - Battery status]] [[Category:83:Ports:By_Name|Battery status]]
== Synopsis ==
'''Port Number:''' 14h

'''Function:''' Battery status checking

This is a read-only port indicating battery status. It also acts as a mirror of the link port on the rest of the bits.

=== Read Values ===
* bit 0: Reads 1 if batteries are high; 0 if they are low.