Category:83Plus:Ports:Unknown - Revision history

Dr. D'nar: Another mystery, revealed

2013-08-12T22:34:51Z

Another mystery, revealed

2013-08-12T03:56:43Z

various updates

2013-04-29T11:31:28Z

2013-03-15T05:20:43Z

‎SE Calculator Ports Only: Port 0x24 resolved.

2013-03-15T05:09:53Z

‎83+ & SE Calculator Ports

2013-02-20T04:47:37Z

TI-84+CSE: 0E and 0F no longer unknown

2011-11-26T02:19:54Z

2011-08-21T17:16:39Z

2011-08-21T05:58:32Z

Updates

2011-07-11T15:56:52Z

@@ Line 11: / Line 11: @@
 ===SE Calculator Ports Only===
 '''Port 17:''' This always reads 0, and writing to it produces no apparent effect. It's a bit suspicious, because all the ports before it and after it have a purpose.
 '''Ports 39 and 3A:'''

@@ Line 7: / Line 7: @@
 ===83+ & SE Calculator Ports===
-* Bits 6, and 7: "Low battery" level is not known. It would be great if somebody with a finely-variable voltage DC power supply tested this.
+* Bits 6, and 7: "Low battery" level is not known. It would be great if somebody with a finely-variable voltage DC power supply tested this. The values are probably controlled using external resistors, because the TI-84+CSE's lithium-ion battery operates at a completely different voltage level.
 ===SE Calculator Ports Only===
 '''Port 17:''' This always reads 0, and writing to it produces no apparent effect. It's a bit suspicious, because all the ports before it and after it have a purpose.
@@ Line 29: / Line 18: @@
 * These ports seem to control GPIO pins, but exactly what those pins connect to is a mystery.
-'''Port 3B:''' The ports before and after this have a purpose. Did TI just happen to skip a port? Reads 0 and writes appear to have no effect.
+'''Port 3B:''' Very like does nothing.
 '''Ports 3C-3F:'''

@@ Line 20: / Line 20: @@
 * Tied to the link assist on the SE calculators. Only written to in boot code where it receives B4. Possibly controls the timeout for sending.
 ** If this is set to E0 or above, the link assist won't throw an error if you write to port 0D without another calculator attached.
 '''Port 2D:'''
-* Only bits 0 and 1 can be altered, but no effect is apparent. Only written to in the boot code, where it receives 02.
+* Only bits 0 and 1 can be altered. Only written to in the boot code, where it receives 02. Writing 0 appears to screw up crystal timing if you HALT.
 '''USB Ports:'''

@@ Line 20: / Line 20: @@
 * Tied to the link assist on the SE calculators. Only written to in boot code where it receives B4. Possibly controls the timeout for sending.
 ** If this is set to E0 or above, the link assist won't throw an error if you write to port 0D without another calculator attached.
 '''Port 2D:'''

@@ Line 7: / Line 7: @@
 ===83+ & SE Calculator Ports===
-'''Port 04:''' Writing:
+* Bits 6, and 7: "Low battery" level is not known. It would be great if somebody with a finely-variable voltage DC power supply tested this.
-* Bit 3: always 0, doesn't seem to have any effect
-* Bit 4: always 1, doesn't seem to have any effect, guessing leftover from 83 code
-* Bits 5, 6, and 7: Bit 7 is known to control the voltage level at which port 02 bit 0 flips. Its default is 0. Bits 5 and 6 are usually left to 1. The EOS messes with bit 6 when testing the battery level. On the TI-89T hardware, bit 5 of a similar port also affects the voltage level threshold. On both the Z80 series hardware and the 68K series hardware, the OS waits for a while between changing this threshold and reading it. It would be great if somebody with a finely-variable voltage DC power supply tested this.
-−
-−
 ===SE Calculator Ports Only===

@@ Line 27: / Line 27: @@
 '''Port 0E:'''
-* Tied with swapping bank $4000. Before swapping pages this port should contain 00, otherwise data read from those pages may not be accurate. Only bits 0 and 1 can be toggled.
+* Tied with swapping bank $4000. Before swapping pages this port should contain 00, otherwise data read from those pages may not be accurate. Only bits 0 and 1 can be toggled. Needs research on the 83+SE.
 '''Port 0F:'''
-* Tied with swapping bank $8000. Before swapping pages this port should contain 00, otherwise data read from those pages may not be accurate. Only bits 0 and 1 can be toggled.
+* Tied with swapping bank $8000. Before swapping pages this port should contain 00, otherwise data read from those pages may not be accurate. Only bits 0 and 1 can be toggled. Needs research on the 83+SE.
 '''Port 24:'''

@@ Line 15: / Line 15: @@
 ===SE Calculator Ports Only===
 '''Port 0B:'''
 * Tied to the link assist on the SE calculators. Only written to in boot code where it receives B4. Possibly controls the timeout for receiving.
@@ Line 20: / Line 24: @@
 '''Port 0C:'''
 * Tied to the link assist on the SE calculators. Only written to in boot code where it receives B4. Possibly controls the timeout for sending.
 '''Port 0E:'''

@@ Line 37: / Line 37: @@
 ==Comments==
-Other ports have unknown functions but are never written to, read from, or change in a significant way. Other ports likely have no purpose at all.
+Other ports have unknown functions but are never written to, read from, or change in a significant way, some likely have no purpose at all.
 There is still quite bit unknown about the hardware, however the remainder is less significant to or can not be used by the average coder.