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General Question 2e — Parallax Forums

General Question 2e

AnthonyAnthony Posts: 4
edited 2004-10-25 19:49 in BASIC Stamp
Hello,
I have a very basic question.· In looking at the comparision chart for the different Stamps, I noticed that the RAM says 6 I/O, and 26 Var.· What exactally does this mean?

Thanks
Anthony

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-25 17:50
    There are 16 IO pins, separated into two groups of eight (byte). For each group there is a DIR register (sets IO state; input or output), and OUT register (value for outputs), and an IN register (current inputs). This makes up six bytes: DIRL, DIRH, OUTL, OUTH, INL, and INH. Note that there is 16-bit, 4-bit, and even 1-bit access to these registers as well.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • allanlane5allanlane5 Posts: 3,815
    edited 2004-10-25 18:13
    And there are 13 word-sized RAM Registers you can use for data/variables. This gives you 13 16-bit Words, 26 8-bit Bytes, 52 4-bit Nibbles, or 208 1-bit BIT variables. The Byte and Word variables are most useful.

    This is kind of tight, but you've only got 2K of EEPROM for program storage anyway, and it is remarkable what you can do with these limited resources.
  • AnthonyAnthony Posts: 4
    edited 2004-10-25 19:44
    Great. I totally understand everything thats going on now. I was just a little confused with the context that was used. Thanks again for the quick reply.

    Anthony
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-25 19:49
    In the end it has to do with PIC/SX architecture and how IO registers are handled.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
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