Difference between revisions of "Category:83Plus:Ports:Unknown"

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(Another mystery, revealed)
 
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===83+ & SE Calculator Ports===
 
===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. The values are probably controlled using external resistors, because the TI-84+CSE's lithium-ion battery operates at a completely different voltage level.
−
* 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===
 
===SE Calculator Ports Only===
−
'''Port 0B:'''
+
'''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.
−
* 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.
+
−
 
+
−
'''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:'''
+
−
* 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.
+
  
−
'''Port 0F:'''
+
'''Ports 39 and 3A:'''
−
* 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.
+
* These ports seem to control GPIO pins, but exactly what those pins connect to is a mystery.
  
−
'''Port 24:'''
+
'''Port 3B:''' Very like does nothing.
−
* This can be set to any value from 0 to 0FFh, but no effect is readily apparent. This is a [[:Category:83Plus:Ports:By_Address:Protected|protected port]].
+
  
−
'''Port 2D:'''
+
'''Ports 3C-3F:'''
−
* Only bits 0 and 1 can be altered, but no effect is apparent.
+
* On DrDnar's TI-84+CSE, these read 78, yet on a TI-84+SE with the TA3 ASIC, they read 00.
  
 
'''USB Ports:'''
 
'''USB Ports:'''

Latest revision as of 14:34, 12 August 2013


Synopsis

There are several ports that have not yet been totally solved. Here is a list of them and what information is available.


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. 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.

Ports 39 and 3A:

  • These ports seem to control GPIO pins, but exactly what those pins connect to is a mystery.

Port 3B: Very like does nothing.

Ports 3C-3F:

  • On DrDnar's TI-84+CSE, these read 78, yet on a TI-84+SE with the TA3 ASIC, they read 00.

USB Ports:

  • All information concerning the USB ports will be handled here.

Comments

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.


Credits and Contributions

  • Tijl Coosemans
  • Dan Englender
  • James Montelongo
  • Michael Vincent

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