diff --git a/README.md b/README.md
index 353e849..6594a51 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 # apple1serial
 
-This repository contains firmware files for the Apple-1 Serial Interface expansion card.
+This repository contains firmware and gerber files for the Apple-1 Serial Interface expansion card.
 
 ## Description
 
@@ -36,7 +36,6 @@ entries for programmers:
 | `$0036` | lower byte of the beginning address for block read/write routines |
 | `$0037` | upper byte of the beginning address for block read/write routines |
 
-
 ## Contents
 
 The contents of this repository are as following:
@@ -76,7 +75,7 @@ http://github.com/flowenol/Apple1SerialPcb
 ## Applesoft BASIC support
 
 You can also `LOAD` and `SAVE` your Applesoft BASIC programs thanks to the branch of the
-applesoft-lite project which has been modified to make use of the A1SI expansion card:
+applesoft-lite project which has been modified to be compatible with the A1SI expansion card:
 
 http://github.com/flowenol/applesoft-lite
 
@@ -84,6 +83,6 @@ http://github.com/flowenol/applesoft-lite
 
 Solder the "C" memory segment line near 74154 demultiplexer to the "T" signal line.
 Afterwards just put the board in right orientation (as marked on the PCB) in the Apple-1 expansion slot.
-Or you can use the port expander if the on board slot is already occupied:
+Or you can use the port expander if the on-board slot is already occupied:
 
 https://github.com/flowenol/Apple1ExpanderPcb
diff --git a/firmware/main.c b/firmware/main.c
index 8e7883a..59eb44e 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -38,13 +38,6 @@ volatile uint8_t data_read_interrupt_count = 0;
 volatile uint8_t receive_buffer[BUFFER_SIZE];
 volatile int8_t receive_index = -1;
 
-// Registers: PCMSK0, PCMSK1, PCMSK2 :registers that enable or disable pin-change interrupts
-// on individual pins
-
-// PCICR : a register where the three least significant bits enable or disable pin change interrupts
-// on a range of pins, i.e. {0,0,0,0,0,PCIE2,PCIE1,PCIE0}, where PCIE2 maps to PCMSK2, PCIE1 maps to PCMSK1,
-// and PCIE0 maps to PCMSK0.
-
 inline void ready() {
     PORTD |= _BV(STATUS);
 }
@@ -61,6 +54,12 @@ inline void put_data() {
     PORTB = lower_part;
 }
 
+// Registers: PCMSK0, PCMSK1, PCMSK2 :registers that enable or disable
+// pin-change interrupts on individual pins.
+// PCICR : a register where the three least significant bits enable or disable
+// pin change interrupts on a range of pins, i.e.
+// {0,0,0,0,0,PCIE2,PCIE1,PCIE0}, where PCIE2 maps to PCMSK2, PCIE1 maps to
+// PCMSK1 and PCIE0 maps to PCMSK0.
 void setup() {
 
     // set input on DATA_READ_LINE