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This port only exists on the the TI-84 Plus and the TI-84 Plus Silver Edition. On the standard TI-83 Plus, it acts as a shadow of port 06. On the TI-83 Plus Silver Edition, this port has no effect.


Port Number: 86h

Equivalent HDRC port: MGC_O_HDRC_INTRUSB (0x0A)

Function: USB Miscellaneous Events

This port reports when various device-level USB events occur.

Read Values

Reading from this port also clears it. Remember the value you read, because you can't go back and read it again.

  • Bit 0
    • Equivalent HDRC name: MGC_M_INTR_SUSPEND, also MGC_M_INTR_EP0
    • Set if the bus has been suspended (no activity for some length of time.)
    • According to the HDRC driver, this bit is also set for endpoint 0 interrupts
  • Bit 1:
    • Equivalent HDRC name: MGC_M_INTR_RESUME
    • (Previous text here: "Probably related to HNP and/or SRP.")
  • Bit 2:
    • Equivalent HDRC name: MGC_M_INTR_RESET, also MGC_M_INTR_BABBLE
    • Set if a bus reset has occurred (both D+ and D- pulled low for some length of time.)
    • May also fire at other times
  • Bit 3:
    • Equivalent HDRC name: MGC_M_INTR_SOF
  • Bit 4:
    • Equivalent HDRC name: MGC_M_INTR_CONNECT
    • Set if a device has been connected (D+, or maybe D?, pulled high for some length of time.)
  • Bit 5:
    • Equivalent HDRC name: MGC_M_INTR_DISCONNECT
    • This usually indicates that something was unplugged.
  • Bit 6:
    • Equivalent HDRC name: MGC_M_INTR_SESSREQ
    • (Previous text here: "Probably related to HNP.")
  • Bit 7:
    • Equivalent HDRC name: MGC_M_INTR_VBUSERROR
    • In host mode, this generally means the calculator cannot provide sufficient power. Usually caused by low batteries, although, some devices cause this every time.
    • Presumably, this could also happen in peripheral mode if the host's power supply sucks, or there is too much voltage drop along the cable.

Write Values

  • No effect


This port is used to report various bus events, which are not associated with any particular endpoint. Note that this port (probably) only works if port 5B bit 0 is set. Port 8B might also act as a mask for this port (note that that port is normally set to A1h in host mode, and 05h in peripheral mode.)