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  • 68060, DBxx loop and IRQs

    From Ralf Kiefer@3:633/10 to All on Monday, September 15, 2025 22:49:14
    From: R.Kiefer.SPAEM@gmx.de

    Hi,

    this is a question hopefully reaching the (small) 68060 community :-)

    Talking about former times we remembered an issue of the 68060 CPU: no
    IRQ handling when in a DBxx loop. But nobody was there who knew real
    facts. Then I asked startpage, duckduckgo .. but no hint. I read my old
    books, the 060 User's manual and the 68000 Family Reference Manual.
    Nothing.

    In a German web forum somebody asked ChatGPT. Better than nothing. But
    do you believe in a language model?

    I have a couple of questions:
    - This issue seems to be a 060 issue. Correct?
    - Are there dependencies to the mask? Back in the 1990s we used some
    MVME177, the CPUs were XC68060, we had 2 masks: 1F43G and 1G65V.
    - Are IRQs blocked just in a DBxx loop without any instruction inside?
    - Which IRQs are involved: just the external IRQs from the peripherals
    (level 1..7) or also internal exceptions like an Address Error or any
    TRAP?

    Regards
    Ralf

    --- SoupGate-Linux v1.05
    * Origin: Dragon's Lair ---:- FidoNet<>Usenet Gateway -:--- (3:633/10)
  • From Buzz McCool@3:633/10 to Ralf Kiefer on Wednesday, September 24, 2025 10:59:25
    From: buzz_mccool@yahoo.com

    On 9/15/2025 1:49 PM, Ralf Kiefer wrote:
    Hi,

    this is a question hopefully reaching the (small) 68060 community :-)

    Talking about former times we remembered an issue of the 68060 CPU: no
    IRQ handling when in a DBxx loop. But nobody was there who knew real
    facts. Then I asked startpage, duckduckgo .. but no hint. I read my old books, the 060 User's manual and the 68000 Family Reference Manual.
    Nothing.

    In a German web forum somebody asked ChatGPT. Better than nothing. But
    do you believe in a language model?

    I have a couple of questions:
    - This issue seems to be a 060 issue. Correct?
    - Are there dependencies to the mask? Back in the 1990s we used some
    MVME177, the CPUs were XC68060, we had 2 masks: 1F43G and 1G65V.
    - Are IRQs blocked just in a DBxx loop without any instruction inside?
    - Which IRQs are involved: just the external IRQs from the peripherals
    (level 1..7) or also internal exceptions like an Address Error or any
    TRAP?

    Regards
    Ralf

    Have you checked the errata?
    https://www.nxp.com/docs/en/errata/MC68060DE.pdf

    I do remember getting MVME177's with XC68060 parts on them because Motorola was taking so long to deliver the 68060. I don't remember having any problems with them.

    --- SoupGate-Linux v1.05
    * Origin: Dragon's Lair ---:- FidoNet<>Usenet Gateway -:--- (3:633/10)
  • From Buzz McCool@3:633/10 to All on Wednesday, September 24, 2025 10:59:25
    On 9/15/2025 1:49 PM, Ralf Kiefer wrote:
    Hi,

    this is a question hopefully reaching the (small) 68060 community :-)

    Talking about former times we remembered an issue of the 68060 CPU: no
    IRQ handling when in a DBxx loop. But nobody was there who knew real
    facts. Then I asked startpage, duckduckgo .. but no hint. I read my old books, the 060 User's manual and the 68000 Family Reference Manual.
    Nothing.

    In a German web forum somebody asked ChatGPT. Better than nothing. But
    do you believe in a language model?

    I have a couple of questions:
    - This issue seems to be a 060 issue. Correct?
    - Are there dependencies to the mask? Back in the 1990s we used some
    MVME177, the CPUs were XC68060, we had 2 masks: 1F43G and 1G65V.
    - Are IRQs blocked just in a DBxx loop without any instruction inside?
    - Which IRQs are involved: just the external IRQs from the peripherals
    (level 1..7) or also internal exceptions like an Address Error or any
    TRAP?

    Regards
    Ralf
    Have you checked the errata?
    https://www.nxp.com/docs/en/errata/MC68060DE.pdf
    I do remember getting MVME177's with XC68060 parts on them because Motorola was taking so long to deliver the 68060. I don't remember having any problems with them.


    --- PyGate Linux v1.0
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate NNTP Gateway (3:633/10)
  • From Ralf Kiefer@3:633/10 to Buzz McCool on Thursday, September 25, 2025 14:13:21
    From: R.Kiefer.SPAEM@gmx.de

    Hi,

    Buzz McCool wrote:

    Have you checked the errata?

    I did, but there is no hint belonging to the DBxx instruction.


    I don't remember having any problems with them.

    We used the MVME177s with a watchdog board (plus a lot of other
    functions) for years without trouble. After years there was a collegue
    who looked for mysterious restarts because of watchdog resets which were
    new, found very long running loops, shortened them and stopped this
    issue.

    Regards
    Ralf

    --- SoupGate-Linux v1.05
    * Origin: Dragon's Lair ---:- FidoNet<>Usenet Gateway -:--- (3:633/10)