US Army Special Forces, Technical Manual, TM 9-1220-239-34, BALLISTICS COMPUTER, XM21, NSN 1220-00-348-8437, 1980

US Army Special Forces, Technical Manual, TM 9-1220-239-34, BALLISTICS COMPUTER, XM21, NSN 1220-00-348-8437, 1980

Scope.
a. This manual is for your use performing direct
support and general support maintenance of the
ballistics comp M21 (fig 1-1), hereinafter referred to a
computer system.

CHAPTER 1. INTRODUCTION
Section I. General 1-1 1-1
II. Description and tabulated data 1-7 1-2
CHAPTER 2. DIRECT SUPPORT AND GENERAL SUPPORT
MAINTENANCE INSTRUCTIONS
Section I. Service upon receipt of materiel 2-1 2-1
II. Preembarkation inspection of materiel in units
altered for overseas shipment 2-5 2-32
III. Troubleshooting 2-6 2-32
IV. General Maintenance 2-8 2-37
CHAPTER 3. REPAIR INSTRUCTIONS
Section I. General 3-1 3-1
II. Repair of gunner's control unit 3-3 3-1
III. Repair of ammo select unit 3-17 3-19
IV. Repair of computer unit 3-24 3-27
CHAPTER 4. FINAL INSPECTION
CHAPTER 5. PREPARATION FOR STORAGE AND SHIPMENT
APPENDIX A. REFERENCES A-1
B. EXPENDABLE SUPPLIES AND MATERIALS LIST B-1
INDEX

1-1 Special Tools, TMDE, and Support Equipment
2-1 Inspection Upon Receipt
2-2 Purging of Computer System Components
2-3 Gunner's Control Unit Checkout
2-4 Computer Unit Checkout
2-5 Ammo Select Unit Checkout
2-6 Troubleshooting
2-7 General Maintenance Procedures List