Subject:
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68HC11 register locations?
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 27 Mar 1998 15:16:57 GMT
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Original-From:
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Mike Vande Weghe <vandeweg@parlance-ncs.&AntiSpam&com>
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Viewed:
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1854 times
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I'm writing an assembly routine under IC on the Handy Board, but I'm
getting a little confused about the memory locations of the 68HC11
registers. The Motorola manual shows that the registers associated with
the input and output timers are in the $1000 range. For instance,
TCTL1=$1020, TMSK1=$1022, TFLG1=$1023. These definitions are also made
in the 6811regs.asm file supplied with IC, so everything seems
consistent. If I look at the IC pcode source, however, I see that an
extra $1000 is added to these addresses. This is done by loading $1000
into the X register (either directly or by using the #BASE symbol, which
is defined to be $1000), and then making all the address references
relative to the X register. For instance,
LDX #BASE
LDA TMSK1,X
etc.
Which is the correct set of address locations? When assembling the
version with the $1000 added I get a "Warning --- Value Truncated" for
each line uses the relative addressing. Anyone have any ideas? Why
does IC add an extra $1000?
Thanks,
- Mike
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Message has 1 Reply:
 | | Re: 68HC11 register locations?
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| (...) The correct actual addresses are indeed all in the $10xx range. When you index off either the X or Y register, the offset value is only 8 bits, or 0 to $FF. This is why you're getting the warning messages, the high order $1000 is being (...) (27 years ago, 28-Mar-98, to lugnet.robotics.handyboard)
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