Added Details

README.md

@@ -1,3 +1,28 @@
 # 8051_Test
 8051 Test code with 4 bit HD44780 LCD, LEDs, audio frequency generation.
-I DO NOT claim that the code is pretty or "correct." Just fiddling with some stuff :-)
+I _DO NOT_ claim that the code is pretty or "correct." Just fiddling with some stuff :-)
+
+YouTube video showing my breadboard and program operation: https://www.youtube.com/watch?v=Z5JveB2_FQQ
+
+I compile with SDCC:
+
+sdcc --iram-size 128 --stack-auto lcd.c
+packihx lcd.ihx > lcd.hex
+
+Since my EPROM programmer only handles raw hex data, no special formats, I also do: 
+
+objcopy -I ihex -O binary lcd.hex lcd.bin
+xxd -p lcd.bin lcd.bin.hex
+
+Those two commands give me a raw binary file, and then convert that binary to the raw ascii hex. 
+
+HD44780 LCD is hooked up to MCU as follows:
+
+LCD: DB4|DB5|DB6|DB7|EN |RS    RW
+P1:   0   1   2   3   4   5    GND 
+
+LEDs and piezo buzzer or speaker are hooked to pins of P3. I used 2.7k has pullup resistors for the LCD lines on P1. I think 4.7k would be more correct but the 2.7ks were what I had handy.
+
+My test circuit is on a breadboard, with external EPROM chip (27c64, but I also used 27256 and 27c512 with success).
+
+