# I (Ron Burkey), the author of this file, declare that it is the Public Domain
# and may be used, altered, or redistributed for any purpose that anybody sees fit.
# Filename:	yaAGC/yaPanel/MdiuTest.obc
# Purpose:	This is a Gemini on-board computer (OBC) assembly-language file
#		which demonstrates/tests OBC access of the MDIU peripheral device.
# Reference:	http://www.ibiblio.org/apollo/Gemini.html
# History:	2012-01-22 RSB	Wrote.

# Usage instructions (if, for example, an emulated OBC is provided by the yaOBC program
# and an emulated MDIU is provided by the yaPanel program, if both of the programs
# are running, with MdiuTest having already been loaded into yaOBC, and if the MDR
# power switch is in the ON position):
#
#   1.	To see a count (in octal) displayed that increments once per second, press 
#	the MDR key labeled READ OUT.
#   2.  To set a different count value:
#	a.  Press MDR CLEAR key to stop the counting and start the data-entry procedure.
#	b.  Enter a 7-digit octal count at on the MDK keypad.
#	c.  Press the MDR ENTER key to finalize the data-entry procedure and start counting.

		CODE	0-00-2-000
		DATA	0-00-0-000

# Variables.  I'm initializing them with zeroes, but they're not constants.
COUNTER		OCT	0		# The current value of the counter
COUNTING	OCT	0		# 1 when counting and 0 when just waiting for input.
KONE		OCT	1		# This *is* a constant.
KZERO		OCT	0		# Another actual constant.
KEYVALUE				# For storing a fetched keystroke
ENTRY		OCT	0		# 0 if in process of entering a number, 1 if not.
	
# This is the program's main loop.  
OBCENTRY	SYN	MAINLOOP	# Mark this as the program-entry point as well.
MAINLOOP	CLD	01		# Numeric keypad key pressed?
		TNZ	NUMBER
		CLD	02		# ENTER key pressed?
		TNZ	ENTER
		CLD	03		# READ OUT key pressed?
		TNZ	READOUT
		CLD	04		# CLEAR key pressed?
		TNZ	CLEAR
		TRA	MAINLOOP

# Number-key pressed.
NUMBER		PRO	443		# Fetch the keystroke, clearing accumulator first.
		STO	KEYVALUE	# Temporarily save the keycode.
		CLA	KONE
		PRO	40		# Reset the MDIU's buffers.
		CLA	ENTRY		# In process of data entry?
		TNZ	MAINLOOP	# No, go back to main loop.
		
		TRA 	MAINLOOP
		
# ENTER key pressed.
ENTER		PRO	40		# Reset the MDIU's buffers.
		CLA	ENTRY		# In process of data entry?
		TNZ	MAINLOOP	# No, go back to main loop.
		
		TRA 	MAINLOOP

# READ OUT key pressed.
READOUT		PRO	40		# Reset the MDIU's buffers.
		CLA	KONE
		STO	COUNTING	# Start counting, if not already counting.
		CLS	KZERO		# And stop data-entry if it's in process.
		STO	ENTRY
		TRA	MAINLOOP

# CLEAR key pressed.
CLEAR		PRO	40		# Reset the MDIU's buffers.
		CLA	KZERO
		STO	COUNTING	# Stops counting, if it's in process.
		CLA	KONE
		STO	ENTRY		# And start data entry process.
		
		TRA	MAINLOOP