Re: A86: Questions on Port 3, calc on, off, APD, etc


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Re: A86: Questions on Port 3, calc on, off, APD, etc




What ROM have you been smoking? At 66 is simply skips the user int routine,
leading someone like me to believe that hey,
NMI's are a possibility. One would assume an ON key interrupt would be an
NMI. But when you do this it wouldnt crash, right?

di
halt

Well it does. An NMI would be executed no matter what, skipping the di
ignoring the halt and interrupting at any time. NMI just
complicates hardware.. just disassembling the rom you can tell that TI
wanted to save time and keep things pretty simple. They also seem to want
the calc really stable too, with all those checksums.

>Well, this is a little late (haven't been paying much attention to the list
in
>the past 2 weeks - still have 241 messages left to read)...  Anyway, if
anyone
>still doesn't believe that there is no NMI, just disassemble at 66h, where
the
>Z80 NMI jumps to.  You'll find that it is nothing.
>
>0038  08        ex      af,af'
>0039  d9        exx
>003a  fdcb2356  bit     2,(iy+$23)
>003e  2826      jr      z,$0066         ; (38)
>0040  3afdd2    ld      a,($d2fd)
>0043  21fed2    ld      hl,$d2fe
>0046  96        sub     (hl)
>0047  2125d3    ld      hl,$d325
>004a  96        sub     (hl)
>004b  214dd3    ld      hl,$d34d
>004e  96        sub     (hl)
>004f  2175d3    ld      hl,$d375
>0052  96        sub     (hl)
>0053  219dd3    ld      hl,$d39d
>0056  96        sub     (hl)
>0057  21c5d3    ld      hl,$d3c5
>005a  96        sub     (hl)
>005b  2005      jr      nz,$0062        ; (5)
>005d  cdfed2    call    $d2fe
>0060  1804      jr      $0066           ; (4)
>0062  fdcb2396  res     2,(iy+$23)
>0066  db03      in      a,($03)
>0068  1f        rra
>0069  3824      jr      c,$008f         ; (36)
>006b  1f        rra
>006c  3828      jr      c,$0096         ; (40)
>006e  1816      jr      $0086           ; (22)
>0070  fdcb1e76  bit     6,(iy+$1e)
>0074  280e      jr      z,$0084         ; (14)
>0076  47        ld      b,a
>0077  db01      in      a,($01)
>0079  4f        ld      c,a
>007a  3eff      ld      a,$ff
>007c  d301      out     ($01),a
>007e  cb41      bit     0,c
>0080  ca5c0c    jp      z,$0c5c
>0083  78        ld      a,b
>0084  d303      out     ($03),a
>0086  3e0b      ld      a,$0b
>0088  d303      out     ($03),a
>008a  08        ex      af,af'
>008b  d9        exx
>008c  fb        ei
>008d  ed4d      reti
>
>It's right in the middle of the intterupt routine!
>
>Matt2000 wrote:
>
>> >> I disassembled the ROM, the interrupt handler is fixed in the code, it
>> makes
>> >> a jump to the ON key interrupt handler routine. I did over 5 hours of
>> >> disassebling and came to the conclusion there are no NMI's.. I have
been
>> >> reading some of the messages about interrupts by Jimmy Mardell and he
>> also
>> >> says "The TI-8x doesn't have any NMI's" and someone (maybe him) also
says
>> >> they haven't even seen a computer with an NMI
>>
>> di
>> halt
>> ret
>>
>> crashes the calc even if the ON key is pressed. It wont HARD lock the
calc
>> (meaning you have to take the lithium battery out)
>> unless you put this code in the interrupt handler. Let me tell you a few
>> things ----
>>
>> - The TI-86 has no NMI's
>> - The ON key interrupt and the timer interrupt are both maskable
interrupts
>> and are both the same kind of interrupt
>>
>> There are some weird things that go on, something leads me to believe
that
>> something other then the ON key produces an
>> ON key interrupt. I am doing experiements to find more information on
this.
>> I am soo close to completing a ROM 1.2 Down-Left bug patch
>>
>> Later,
>>     Matt
>
>
>
>--
>Stephen Hicks
>mailto:shicks@mindspring.com
>ICQ:5453914
>IRC/AIM:Kupopo
>Hopemage:http://www.mindspring.com/~shicks/
>
>


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