The following was my first "for real" computer program at White Sands Missle Range,
New Mexico, written in assembly language for the IBM 1401 computer. This was before
the days of compiler languages such as FORTRAN. I was a co-op student majoring in 
physics at New Mexico State University.
The first section was a typed instruction sheet.
The second section shows the program as listed by the computer.
----------------------------------------------------------------------------------- 

			FIRST DIFFERENCES PROGRAM
			IBM 1401-TAPE TO PRINTER

James D. Hartsell - 30 Jul 1962

LOAD CARD:
	Col. 1-6 Project number
	Col. 10-13 ^t; decimal point is between col. 10 and 11.
	     Punch a load card for each run if different.

OPERATING INSTRUCTIONS:
	1. Put input tape on Tape Unit Nr. 2
	2. Sense Switch A on.
	3. Load program with first load card behind it. Read in load card again
	   if a -99 is at the beginning of the first run.
	4. if ^t was punched wrong, ^x, ^y, and ^z will not print out.
	5. If the project number was punched wrong, there will be no output after
	   printing the IDEN line, but the 1401 lights will be flashing.
	6. A 1873 stop indicates the end of the run has been reached. Put next
	   load card in reader and hit start.
	7. A 1890 stop indicates an end of file.

OPERATING FEATURES:
	1. The I.D. line and "COMPUTATION OF FIRST DIFFERENCES" will be printed
	   at beginning of run.
	2. ^x, ^y, and ^z will be computed,
	   where:    ^x = x2-x1    ^y = y2 - y1    ^z = z2 - z1
	3. Negative signs will be printed to the right of the result.
	4. Garbage at the beginning of or between runs is ignored.
	5. This program will compute first differences on any input tape
	   where data is in BCD tape fields 3, 4, and 5 such as x, y, z on
	   FPS-16 unsmoothed positions.
-----------------------------------------------------------------------------------

LABEL	OP	A OPERAND	B OPERAND	D
------	---	---------	---------	---

	CTL	3
	ORG	0800
GRPMRK  DC	*
BLANKS	DCW	*
HEADIN	DCW	*		COMPUTATION OF FIRST DIFFERENCES
CNTR1	DCW	*
CNTR2	DCW	*
ONE	DCW	*				1
	DCW	*		TAPE ERROR - ALL ATTEMPTS TO REA
COMM	DC	*		 D HAVE FAILED - DISCONTINUE RUN
ID1	DCW	*				-119
ID2	DCW	*				- 19
ECR	DCW	*				- 99
EOF	DCW	*
ZERO	DCW	*				0
EDIT	DCW	*				0 -
ZEROES	DCW	*				000
NEG	DCW	*				-
ACC1	DCW	*
ACC2	DCW	*
ACC3	DCW	*
ACC4	DCW	*
START	CS	0080
	CS	0299
	CS	0332
RDLDOD	R
	SW	0001		0010
	SW	0521		0721
	MCW	GRPMK		0521
	MCW	GRPMK		0721
RDTAPE	MCW	(U2		0601		R
	SW	0601		0605
	B	TAPER				L
	B	SKIP				-
PROJNO	C	0610		0006
	B	IDEN				/
	MZ	ONE		0601
	SW	0087		
	LCA	ZEROES		0089
TESTT	BWZ	MVNEGT		0611	1	K
	A	ONE		0089
	B	TESTX		0089		8
	B	TESTT		
MVNEGT	MZ	NEG		0619
	MZ	ONE		0611	1
TESTX	LCA	ZEROES		0089
	BWZ	MVNEGX		0621	1	K
	A	ONE		0089
	B	TESTY		0089		8
	B	TEXTX +007
MVNEGX	MZ	NEG		0629
	MZ	ONE		0621	1