Changeset 34
- Timestamp:
- Sep 3, 2010, 2:56:55 PM (11 years ago)
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Deliverables/D4.1/Presentation/Paris-September-2010.tex
r33 r34 57 57 \frametitle{Bit memory} 58 58 \begin{itemize} 59 The 8051 provides 128 bit variables to the user, at locations 59 \item 60 The 8051 provides 128 bit variables to the user, numbered 00h--7Fh. 61 \item 62 Like the `R' registers, bit memory is really a part of internal RAM. 63 \item 64 Bit memory is located at internal RAM addresses 20h--2Fh, therefore writing FFh to internal RAM address 20h effectively sets bits 00h through 07h. 65 \item 66 Though part of internal RAM, the 8051 provides specific instructions for setting and clearing bits in bit memory. 60 67 \end{itemize} 61 68 \end{frame} 69 70 \begin{frame} 71 \frametitle{A note on the stack pointer (SP)} 72 \begin{itemize} 73 \item 74 At powerup, the 8051 initialises the SP to address 07h. 75 \item 76 The stack therefore starts at 08h and expands upwards. 77 \item 78 Care must be taken if we decide to use the alternative register banks to initialise the stack pointer above the chosen bank. 79 \item 80 Further, if using bit variables, it's a good idea to initialise the stack point above address 2Fh, to ensure bit variables are not overwritten by the growing stack. 81 \end{itemize} 82 \end{frame} 83 84 \begin{frame} 85 \frametitle{Special function registers (SFRs)} 86 \end{frame} 87 62 88 \end{document}
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