2020-06-03 03:39:34 +00:00
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# Apple II/II+ Encoder
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This is a version of the ASCII interface wired up to be compatible with the
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Apple II/Apple II+ keyboard matrix. This board was broken out as a separate PCB
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from the Atmega2560-based interface board on which it was based, in order to
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keep the "custom" connector customizable on that board.
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This board is otherwise identical to rev 3.4 of the ATMega2560-based ASCII interface board, and shares the same firmware and features.
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<img alt="Assembly Rendering" src="images/PCB-assembly-rendering.png" height=75%
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width=75%>
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## Features
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- Parallel or serial output
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- Up to 8 configuration settings via an up-to-8 position DIP switch
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- Apple 1, Apple 2, and SOL-20 compatible outputs. Other configurations can be
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supported by making a custom cable.
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- Can decode arbitrary keyboards up 16 rows by 8 columns.
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- Supports up to 3 keyboard LEDs
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- Supports up to 3 "special" host outputs, such as RESET, SCREEN_CLEAR, BREAK, etc.
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- Socket for custom connector
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## Assembly Notes
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2021-01-16 04:49:34 +00:00
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- You may build this board as if it is a general purpose ASCII interface. In
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2020-06-03 03:39:34 +00:00
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that case, you may want to avoid installing the 1x25 Apple2 keyboard header
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2021-01-16 04:49:34 +00:00
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if it interferes with the target keyboard matrix.
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2020-06-03 03:39:34 +00:00
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2021-01-16 04:49:34 +00:00
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- This encoder is normally used with keyboards that have a diode per key. For use
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with a key matrix with no diodes (such as the Apple 2 key matrix), cut the PCB
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traces that short diodes D1-16, and install D1-16.
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- If you ARE building this board as an Apple 2 encoder, then you may OMIT:
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- Sol-20 connector J5
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- Custom connector J7
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- D17,D18,D19 - These are used for the "classic" keyboard matrix.
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- D7,D8,D15,D16 - These are diodes for rows 12-15, which are not used.
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- The serial out connector J3 if you do not plan to use a serial output.
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- The I/O connector J4, as all the I/O lines are routed through the
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2020-06-03 03:39:34 +00:00
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keyboard connector.
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2021-01-16 04:49:34 +00:00
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- If you will be using the keyboard with only an Apple 1 or Apple 2, then
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2020-06-03 03:39:34 +00:00
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you do not need to install both the Apple 2 connector (J1) AND the Apple
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1 connector (J2). You may install only the one you plan to use, and
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reduce the risk of plugging into the wrong socket (and possibly damaging
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the encoder).
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1. Solder the surface-mount microcontroller first. Be sure to match pin 1 to the
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dot on the silk-screen layer.
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1. Next, install the surface mount crystal, Y1. The orientation is not important.
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2021-01-16 04:49:34 +00:00
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1. Next, solder in the resitor R1
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1. Install all the capacitors. Be sure to separate out the two capacitors for the XTAL
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circuit from the other capacitors, the rest of which are 0.1uF bypass capacitors.
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2020-06-03 03:39:34 +00:00
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1. Install the In-circuit Serial Programming (ISP) header, J6. (right-angle, 2x3
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0.100")
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1. If you will be using the Apple 1 connector, install the DIP socket J1 (16-pin
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dip). If you plan to insert and remove the cable many times, a dual-wipe
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socket may be preferable to machine-pin, since it has a lower insertion
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force, and you will be less likely to bend pins. If you plan to insert the
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cable once and leave it forever, I suggest a machine-pin DIP socket.
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1. If you will be using the Apple 2 connector, install the DIP socket J2 (16-pin
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dip). The note for the Apple 1 connector selection applies here as well.
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