8051 Development System Circuit Board 3

  
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A newer version of this circuit board is available. Rev 4 includes a faster CPU, more memory, more I/O and an optional LCD. We recommend you use Rev 4 for new projects. Even though this older board is no longer available, we are keeping these old pages on-line for reference to assist people who purchased or build the older version. This i
8051 Development System Circuit Board 3 - schematic

s the complete schematic for the development board. Address and Data bus wires are drawn separately (not in a bus), so that it`s easy to color over them on a printout, if you choose to manually connect the wires. It really is easier to buy a bare circuit board, though. This design and its schematic have been placed in the public domain. They are distributed in the hope that they will be useful, but are provided without any warranty, not even a warranty of merchantability or fitness for a particular purpose. The address bus in this schematic is connected in an unusual way, which is optimized for simpler point-to-point wiring. For anyone building the board using wire-wrap or hand soldered point to point construction, this wiring scheme makes for much less clutter in the wiring if the chips are positioned similarily to the layout on the printed circuit board. Very few wires cross over one another. This also makes the PC board layout a bit simpler, allowing wider traces and fewer vias. This unusual address bus wiring works. The 74HC373 chip (U2) is 8 identical flip-flops, so it does not matter which one is used for each line. On the RAM (U3) and Flash ROM (U4) chips, all data that is stored in these chips is written by the 87C52 chip (U1), so it does not matter which physical location within the chip is mapped into each location within the CPU`s address space, because each read from these chips will return the same data that...



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