legOS : 2949


Robotics / RCX / legOS / 2949	2948 \| 2950

Subject:	Re: Motor Control Register (0xf000)
Newsgroups:	lugnet.robotics.rcx, lugnet.robotics.rcx.legos
Date:	Thu, 14 Nov 2002 09:34:01 GMT
Viewed:	234 times

"Mark Riley" <markril@hotmail.com> writes: > > It also turns out that there are 8 bytes of external > RAM that peek through at addresses 0xff80-0xff87. > Writes to these locations also affect the motor > control register. I suppose there's a small advantage > in using these registers to control the motor since > accesses to these locations can use the processor's > 8 bit addressing modes. And, because of the > "shadowing" by the RAM, the various bit instructions > seem to work fine. I bet the H8 designers left this > little hole just so these instructions could be used > on external devices. In that case, why didn't the RCX designers use an 8 input NAND to decode their addresses, to leave more of the RAM usable? Maybe there werent aware of this possibility? Jürgen -- Jürgen Stuber <stuber@loria.fr> http://www.loria.fr/~stuber/ I åa ä e ö å i öa ä e å.

Message has 1 Reply:

		Re: Motor Control Register (0xf000)
(...) As it is, it seems[1] that two of the three NAND gates in the 74HC10 are being used as a driver for speaker output (it's odd that it's two, not one though). So, this leaves one three input NAND gate to do the decoding. Now that I think about (...) (22 years ago, 14-Nov-02, to lugnet.robotics.rcx, lugnet.robotics.rcx.legos)

Message is in Reply To:

		Re: Motor Control Register (0xf000)
It also turns out that there are 8 bytes of external RAM that peek through at addresses 0xff80-0xff87. Writes to these locations also affect the motor control register. I suppose there's a small advantage in using these registers to control the (...) (22 years ago, 14-Nov-02, to lugnet.robotics.rcx, lugnet.robotics.rcx.legos)

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