README.md update to add assembly image

hardware/interface-ascii/README.md

@@ -1,24 +1,34 @@
 # ASCII Interface - Atmega328p
 
-This is is a key scanner module with parallel output, and optional serial output, supporting keyboards
+This is is a key scanner module with parallel output, and optional serial
-of up to 16 rows X 8 columns.
+output, supporting keyboards of up to 16 rows X 8 columns.
+
+The ATMega 328P was selected for the sole reason that it is an architecture
+familiar to many hobbyists, with an accessible programming environment and
+ecosystem, in a DIP format that fits the retro look and is easy to solder for
+most hobbyists. All of the ICs, other than the microcontroller, are only present
+to compensate for the limited number of GPIO lines on this small 28-pin
+microcontroller. Using a bigger chip would greatly simplify the hardware and
+even slightly simplify the hardware layer of the firmware.
+
+<img alt="Assembly Rendering" src="images/images/PCB-assembly-rendering.jpg" height=75% width=75%>
 
-The ATMega 328P was selected for the sole reason that it is an architecture familiar to many hobbyists,
-with an accessible programming environment and ecosystem, in a DIP format that fits the retro look and is
-easy to solder for most hobbyists.  All of the ICs, other than the microcontroller, are only present to
-compensate for the limited number of GPIO lines on this small 28-pin microcontroller.  Using a bigger chip
-would greatly simplify the hardware and even slightly simplify the hardware layer of the firmware.
 
 ## Overview
-- The keyboard rows are driven by a pair of 74LS138 decoders, allowing 4 GPIO lines to drive 16 rows.
+- The keyboard rows are driven by a pair of 74LS138 decoders, allowing 4 GPIO
+  lines to drive 16 rows.
 - The columns are read in via an 8-bit shift register, controlled by 3 GPIO lines.
 - One 8-bit port is used for the parallel ASCII output.
-- Two GPIO lines are used to generate special outputs to the host.  These could be RESET, BREAK, CLEAR, etc.
+- Two GPIO lines are used to generate special outputs to the host. These could
+  be RESET, BREAK, CLEAR, etc.
 - One GPIO line is used to control a keyboard LED.
-- Three of the ISP lines are also used as outputs to controll two more Keyboard LEDs and one more "special" output line.
+- Three of the ISP lines are also used as outputs to controll two more Keyboard
-- The top two parallel I/O bits can also be configured as UART I/O.  This could be used to provide serial output instead
+  LEDs and one more "special" output line.
-or parallel output, to support a bootloader, or even to accept a serial input stream from another computer to send to the
+- The top two parallel I/O bits can also be configured as UART I/O. This could
-host as parallel ASCII data.  This last application would require careful timing to avoid conflicts.
+be used to provide serial output instead or parallel output, to support a
+bootloader, or even to accept a serial input stream from another computer to
+send to the host as parallel ASCII data. This last application would require
+careful timing to avoid conflicts.
 
 ## Assembly Notes
 
@@ -27,37 +37,43 @@ The minimum functioning circuit includes
 1. the 74LS166 shift register (U2)
 1. one 74LS138 decoder (U3).
 1. The resistor network RN1
-1. The two resistors R3 and R4.  If you are using the keyboard in only a parallel configuration or only a
+1. The two resistors R3 and R4. If you are using the keyboard in only a parallel
-serial configuration, then you can jumper these resistors with a piece of wire.
+configuration or only a serial configuration, then you can jumper these
+resistors with a piece of wire.
 1. Any connectors required.
 
 ## Optional components
 ### Diodes D1-D16
-These diodes are intended to mitigate ghosting when used with a keyboard matrix that does not have
+These diodes are intended to mitigate ghosting when used with a keyboard matrix
-any diodes installed.  These provide one diode per row.  If you are attaching a keyboard with no diodes, then you only need
+that does not have any diodes installed. These provide one diode per row. If you
-to populate the diodes corresponding to rows on the keyboard.  If the keyboard has 8 rows, then you may want to install
+are attaching a keyboard with no diodes, then you only need to populate the
-8 diodes corresponding to those rows.
+diodes corresponding to rows on the keyboard. If the keyboard has 8 rows, then
+you may want to install 8 diodes corresponding to those rows.
 
-Note that the footprints for these diodes include a copper jumper on the TOP copper layer.  If you install any of these
+Note that the footprints for these diodes include a copper jumper on the TOP
-diodes, you should cut the jumpers for those diodes.  Otherwise the diodes do nothing.
+copper layer. If you install any of these diodes, you should cut the jumpers for
+those diodes. Otherwise the diodes do nothing.
 
 ### DIP switch and associated diodes
-The DIP switch is optional.  If you don't want to be able to set options via the DIP switches, you can set all your 
+The DIP switch is optional. If you don't want to be able to set options via the
-preferences in the firmware, or just accept the default behavior, and skip the DIP switch and Diodes D17-D20 and D24-D27.
+DIP switches, you can set all your preferences in the firmware, or just accept
+the default behavior, and skip the DIP switch and Diodes D17-D20 and D24-D27.
 
 ### Second 74LS138 multiplexer (U4)
 Only needed if you have more than 8 rows.
 
 ### The 74LS07 hex buffer (U5)
-Only needed if you are using LED2 or LED3 on the keyboard, or the OUT2 open collector output.
+Only needed if you are using LED2 or LED3 on the keyboard, or the OUT2 open
+collector output.
 
 ### Diodes D21, D22, D23
-Some keyboards may not wire all keys into the matrix. For example, some other interface modules may
+Some keyboards may not wire all keys into the matrix. For example, some other
-assign special hardware functions to certain keys.  Those keys are brought directly to the keyboard
+interface modules may assign special hardware functions to certain keys. Those
-connector.  For the classic keyboard, the POWER key, the '@' key, and the RUBOUT key are not directly wired.
+keys are brought directly to the keyboard connector. For the classic keyboard,
-This module wires them into the matrix via D21, D22, and D23, respectively.  For keyboards with no separately wired
+the POWER key, the '@' key, and the RUBOUT key are not directly wired. This
-keys, these diodes may be omitted.
+module wires them into the matrix via D21, D22, and D23, respectively. For
+keyboards with no separately wired keys, these diodes may be omitted.
 
 ### Resistors R1, R2, R5
-These resistors provide current limiting for up to three keyboard LEDs.  If no keyboard LEDs are installed, then these
+These resistors provide current limiting for up to three keyboard LEDs. If no
-resistors can be ommitted.
+keyboard LEDs are installed, then these resistors can be ommitted.