LA120 Technical Manual

Company:	Digital Equipment Corporation
Part:	EK-LA120-TM-001
Date:	1980-01
Keywords:	DECwriter III

Chapter 1 Operator's Information
- 1.1 Introduction
- 1.2 Operator's Console
  - 1.2.1 Lights
  - 1.2.2 Local Control Keys
  - 1.2.3 SET-UP Keys
  - 1.2.4 Control Character Keys
  - 1.2.5 Other Keys
  - 1.2.6 Optional Numeric Keypad
  - 1.2.7 Power ON/OFF Switch and Voltage Selector Switch
  - 1.2.8 Cover Interlock Switch
  - 1.2.9 Paper Adjust Knob
  - 1.2.10 Tractor Adjust Knobs
  - 1.2.11 Carriage Adjustment Lever
- 1.3 Alarm Indicators
- 1.4 Operator Testing and Troubleshooting
Chapter 2 Installation, Interface, and Specifications
- 2.1 Installation and Configuration
  - 2.1.1 Unpacking and Inspection
  - 2.1.2 Packing Procedures
  - 2.1.3 Checkout Procedure
  - 2.1.4 Answerback Jumper
- 2.2 Interface Information
  - 2.2.1 Interface Signals
    - 2.2.1.1 Protective Ground
    - 2.2.1.2 Transmitted Data (TDX)
    - 2.2.1.3 Received Data (RDX)
    - 2.2.1.4 Request to Send (RTS)
    - 2.2.1.5 Clear to Send (CTS)
    - 2.2.1.6 Data Set Ready
    - 2.2.1.7 Signal Ground
    - 2.2.1.8 Carrier Detect (RLSD)
    - 2.2.1.9 Secondary Request to Send (SRTS)
    - 2.2.1.10 Speed Indicator (SPDI)
    - 2.2.1.11 Secondary Carrier Detect (SRLSD)
    - 2.2.1.12 Data Terminal Ready (DTR)
    - 2.2.1.13 Ring Indicator (RI)
    - 2.2.1.14 Speed Select (SPDS)
  - 2.2.2 EIA Interface Cables
    - 2.2.2.1 BC22A-10, -25
    - 2.2.2.2 BC22B-10, -25
  - 2.2.3 Impedance of Terminator
  - 2.2.4 Rise and Fall Times
  - 2.2.5 Open Circuit Voltage
- 2.3 LA120 Specifications
Chapter 3 Programmer's Information
- 3.1 General
- 3.2 Escape Sequences
  - 3.2.1 Parser Program
  - 3.2.2 Sequence Descriptions
    - 3.2.2.1 Printer Character Sets
    - 3.2.2.2 Active Position
    - 3.2.2.3 Linefeed-Newline Mode
    - 3.2.2.4 Horizontal Pitch
    - 3.2.2.5 Horizontal Margins
    - 3.2.2.6 Horizontal Tabs
    - 3.2.2.7 Vertical Pitch
    - 3.2.2.8 Form Length
    - 3.2.2.9 Vertical Margins
    - 3.2.2.10 Vertical Tabs
    - 3.2.2.11 Product Identification
    - 3.2.2.12 Alternate Keypad Mode
- 3.3 Control Characters
  - 3.3.1 Null or Delete (NULL or DEL)
  - 3.3.2 End of Text (ETX)
  - 3.3.3 End of Transmission (EOT)
  - 3.3.4 Enquiry (ENQ)
  - 3.3.5 Bell (BEL)
  - 3.3.6 Backspace (BS)
  - 3.3.7 Horizontal Tab (HT)
  - 3.3.8 Line Feed (LF)
  - 3.3.9 Vertical Tab (VT)
  - 3.3.10 Form Feed (FF)
  - 3.3.11 Carriage Return (CR)
  - 3.3.12 Shift In (SI)
  - 3.3.13 Shift Out (SO)
  - 3.3.14 Data Link Escape (DLE)
  - 3.3.15 Cancel (CAN)
  - 3.3.16 Substitute (SUB)
  - 3.3.17 Escape (ESC)
- 3.4 APL Character Set
- 3.5 Sample Form Setup Using Escape Sequences
- 3.6 Synchronization
  - 3.6.1 Synchronization Limits
  - 3.6.2 Fill Time Formulas
    - 3.6.2.1 Horizontal Movement
    - 3.6.2.2 Vertical Movement
- 3.7 Keyboard Operation
  - 3.7.1 Auto Repeat
  - 3.7.2 Printable Character Keys
  - 3.7.3 Control Character Keys
  - 3.7.4 CTRL (Control) Key
  - 3.7.5 Optional Auxiliary Keypad
  - 3.7.6 BREAK Key
  - 3.7.7 VIEW Key
Chapter 4 LA120 Theory of Operation
- 4.1 Basic System Configuration
  - 4.1.1 Microprocessor
  - 4.1.2 Device Addressing
    - 4.1.2.1 Memory Space
    - 4.1.2.2 I/O Space
  - 4.1.3 Interrupts
  - 4.1.4 ROM
  - 4.1.5 RAM
  - 4.1.6 Keyboard
    - 4.1.6.1 Keyboard Addressing
    - 4.1.6.2 Switch Matrix
    - 4.1.6.3 Separately Decoded Keys
  - 4.1.7 Display
    - 4.1.7.1 LEDs
    - 4.1.7.2 Seven Segment Display
  - 4.1.8 Non-Volatile Memory
  - 4.1.9 DC305 Printer Controller
  - 4.1.10 8251A USART
  - 4.1.11 Utility I/O Ports
- 4.2 DC305 Printer Controller
  - 4.2.1 Dot Print Control
  - 4.2.2 Carriage Position Count
  - 4.2.3 Carriage Speed Control
  - 4.2.4 Line Feed Control
  - 4.2.5 Bell Control
  - 4.2.6 Frequency Generation
  - 4.2.7 Tick Alarm
  - 4.2.8 Interrupt Vectors
- 4.3 LA120 Firmware Overview
  - 4.3.1 Scheduling
  - 4.3.2 ROM Layout
  - 4.3.3 RAM Layout
- 4.4 Print Control Firmware
  - 4.4.1 Starting the Print Operation
  - 4.4.2 Flight Time Compensation
  - 4.4.3 Dot Rate Limiting
- 4.5 Carriage Servo Firmware
  - 4.5.1 Transitions
  - 4.5.2 Reading the Position Counter
  - 4.5.3 Carriage Speed Command
  - 4.5.4 Error Conditions
- 4.6 Communication Firmware
  - 4.6.1 Communication Modes
  - 4.6.2 Local Mode
  - 4.6.3 Disconnects
  - 4.6.4 Full Duplex Without EIA Controls
  - 4.6.5 Full Duplex with EIA Controls
    - 4.6.5.1 Full-Duplex Break
    - 4.6.5.2 Full-Duplex Disconnect
    - 4.6.5.3 Restraint Mode
    - 4.6.5.4 Speed Control Mode
  - 4.6.6 Half Duplex
    - 4.6.6.1 Initial Direction Determination
    - 4.6.6.2 Reverse Channel
    - 4.6.6.3 Request to Send Delay
    - 4.6.6.4 Turnaround Characters
    - 4.6.6.5 Half-Duplex Break
    - 4.6.6.6 Half-Duplex Disconnect
  - 4.6.7 Communication State Control
    - 4.6.7.1 Communication State Table
    - 4.6.7.2 Communication Handler
  - 4.6.8 Control Code Generation and Detection
    - 4.6.8.1 Input Scanning
    - 4.6.8.2 Transmit Scanning
    - 4.6.8.3 Control Code Generation
  - 4.6.9 Functional State Diagrams
- 4.7 Escape Sequence Processing
  - 4.7.1 Escape Sequence State Transition Table
    - 4.7.1.1 Element No. 1
    - 4.7.1.2 Element No. 2
    - 4.7.1.3 Element No. 3
    - 4.7.1.4 Element No. 4
    - 4.7.1.5 Element No. 5
    - 4.7.1.6 Element No. 6
    - 4.7.1.7 Element No. 7
  - 4.7.2 Escape Sequence Jump Table
  - 4.7.3 Escape Sequence Parser
    - 4.7.3.1 Begin Parsing
    - 4.7.3.2 Initialize Parser
    - 4.7.3.3 Flow Controller
  - 4.7.4 CSI Parameters
  - 4.7.5 Control Strings
  - 4.7.6 Final Character Perform-Function Routines
- 4.8 SET-UP Command Processing
  - 4.8.1 SET-UP Command Implementation
    - 4.8.1.1 Multiple Choice SET-UP Commands
    - 4.8.1.2 Immediate Action SET-UP Commands
  - 4.8.2 SET-UP Handler
  - 4.8.3 SET-UP/Keyboard Handler Relationship
- 4.9 Character Processing
  - 4.9.1 Character Reception
  - 4.9.2 Background Executive
  - 4.9.3 Print Line Builder
  - 4.9.4 Answerback Entry Handler
Chapter 5 Troubleshooting the LA120
- 5.1 General
- 5.2 DC Servo Test
- 5.3 Encoder Duty Cycle Check/Adjustment
- 5.4 Clock Test
- 5.5 Wake Up Test
- 5.6 Print Character Test
- 5.7 USART Test
- 5.8 Keyboard Test
- 5.9 Line Feed Test
- 5.10 Bell Test
Chapter 6 LA120 Subassembly Removal and Installation
- 6.1 General
- 6.2 Printer Housing
  - 6.2.1 Printer Housing Removal
  - 6.2.2 Printer Housing Installation
- 6.3 Print Head Assembly
  - 6.3.1 Print Head Assembly Removal
  - 6.3.2 Print Head Assembly Installation
- 6.4 Print Head Cable
  - 6.4.1 Print Head Cable Removal
  - 6.4.2 Print Head Cable Installation
- 6.5 Timing Belt
  - 6.5.1 Timing Belt Removal
  - 6.5.2 Timing Belt Installation
- 6.6 Print Bar
  - 6.6.1 Print Bar Removal
  - 6.6.2 Print Bar Installation
- 6.7 Carriage Assembly and Front Carriage Shaft
  - 6.7.1 Carriage Assembly and Front Carriage Shaft Removal
  - 6.7.2 Carriage Assembly and Front Carriage Shaft Installation
- 6.8 Carriage Eccentric Bearing and Lever
  - 6.8.1 Carriage Eccentric Bearing and Lever Removal
  - 6.8.2 Carriage Eccentric Bearing and Lever Installation
- 6.9 Rear Carriage Shaft and Plain Bushing
  - 6.9.1 Rear Carriage Shaft and Plain Bushing Removal
  - 6.9.2 Rear Carriage Shaft and Plain Bushing Installation
- 6.10 Ribbon Drive Pulley
  - 6.10.1 Ribbon Drive Pulley Removal
  - 6.10.2 Ribbon Drive Pulley Installation
- 6.11 Ribbon Drive Assembly
  - 6.11.1 Ribbon Drive Assembly Removal
  - 6.11.2 Ribbon Drive Assembly Installation
- 6.12 Ribbon Drive Fafnir Bearing
  - 6.12.1 Ribbon Drive Fafnir Bearing Removal
  - 6.12.2 Ribbon Drive Fafnir Bearing Installation
- 6.13 Ribbon Eccentric and Backstop Spring
  - 6.13.1 Ribbon Eccentric and Backstop Spring Removal
  - 6.13.2 Ribbon Eccentric and Backstop Spring Installation
- 6.14 DC Motor and Encoder Assembly
  - 6.14.1 DC Motor and Encoder Assembly Removal
  - 6.14.2 DC Motor and Encoder Assembly Installation
- 6.15 Tractor Drive Shafts and Tractor Assemblies
  - 6.15.1 Tractor Drive Shafts and Tractor Assembly Removal
  - 6.15.2 Tractor Drive Shafts and Tractor Assembly Installation
- 6.16 Idler Gear Assembly
  - 6.16.1 Idler Gear Assembly Removal
  - 6.16.2 Idler Gear Assembly Installation
- 6.17 Stepping Motor Assembly
  - 6.17.1 Stepping Motor Assembly Removal
  - 6.17.2 Stepping Motor Assembly Installation
- 6.18 Ribbon Chassis Assembly
  - 6.18.1 Ribbon Chassis Assembly Removal
  - 6.18.2 Ribbon Chassis Assembly Installation
- 6.19 Ribbon Spool Ratchet Wheels and Friction Disks
  - 6.19.1 Ribbon Spool Ratchet Wheel(s) and Friction Disk Removal
  - 6.19.2 Ribbon Spool Ratchet Wheel(s) and Friction Disk Installation
- 6.20 Keyboard/Numeric Pad Assembly
  - 6.20.1 Keyboard/Numeric Pad Assembly Removal
  - 6.20.2 Keyboard/Numeric Pad Assembly Installation
- 6.21 Power Supply Assembly
  - 6.21.1 Power Supply Assembly Removal
  - 6.21.2 Power Supply Assembly Installation
- 6.22 Printer Mechanism Assembly
  - 6.22.1 Printer Mechanism Assembly Removal
  - 6.22.2 Printer Mechanism Assembly Installation
- 6.23 CVT Power Supply Module
  - 6.23.1 CVT Power Supply Module Removal
  - 6.23.2 CVT Power Supply Module Installation
- 6.24 Power Entry Bracket Assembly
  - 6.24.1 Power Entry Bracket Assembly Removal
  - 6.24.2 Power Entry Bracket Assembly Installation
- 6.25 Fan
  - 6.25.1 Fan Removal
  - 6.25.2 Fan Installation
- 6.26 Logic/Power Board
  - 6.26.1 Logic/Power Board Removal
  - 6.26.2 Logic/Power Board Installation
Chapter 7 Adjustment Procedures and Lubrication
- 7.1 Print Head Adjustment
- 7.2 Printer Mechanism Adjustment
- 7.3 Paper Guide Adjustment
- 7.4 Paper Out Switch Adjustment
- 7.5 Ribbon Tension Adjustment
- 7.6 Ribbon Drive Assembly Adjustment
- 7.7 Idler Gear Assembly Adjustment
- 7.8 Bumper Assembly Adjustment
- 7.9 Print Bar Adjustment
- 7.10 Lubrication
Chapter 8 20 mA LA12X-AL Option
- 8.1 General
- 8.2 Installation
- 8.3 Test After Installation
- 8.4 Electrical Characteristics
  - 8.4.1 Transmitter
  - 8.4.2 Receiver
  - 8.4.3 Pin Assignments
Chapter 9 Expanded Buffer Option LA12X-DL
Chapter 10 LA120-RE
- 10.1 Introduction
- 10.2 Installation
Chapter 11 LA12X-HL Keyboard Option
- 11.1 Introduction
- 11.2 Installation
- 11.3 Operator's Information
Chapter 12 LA12X-YL Option
- 12.1 Introduction
- 12.2 Installation
- 12.3 Operator's Information
  - 12.3.1 Indicator Lights
  - 12.3.2 Control Keys
  - 12.3.3 SET-UP Mode
  - 12.3.4 Baud Rate (Speed)
  - 12.3.5 Parity and Data Bits
  - 12.3.6 Setting Form Length
  - 12.3.7 Printer New Line Character
  - 12.3.8 Modem
  - 12.3.9 Secondary Channel
  - 12.3.10 Status
  - 12.3.11 Store/Recall
Appendix A LA120 Operator Reference Card
Appendix B Factory Parameter Settings

Copies

Address:	http://vt100.net/docs/la120-tm/la120tm1.pdf
Site:	Paul Williams' VT100.net
Format:	PDF
Size:	15300402 bytes (14.6 MiB)

Address:	http://www.computer.museum.uq.edu.au/unfinished/EK-LA120-TM-001%20LA120%20Technical%20Manual.tif
Site:	Wilber Williams' Computer Museum
Format:	TIFF
Size:	25096524 bytes (23.9 MiB)
Notes:	Awaiting clean-up and conversion to PDF

Address:	http://www.computer.museum.uq.edu.au/pdf/EK-LA120-TM-001%20LA120%20Technical%20Manual.pdf
Site:	Wilber Williams' Computer Museum
Format:	PDF
Size:	15300402 bytes (14.6 MiB)

Comments, queries or problems to <manx(frixxon.co.uk)>

Manx – a catalogue of online computer manuals

LA120 Technical Manual

Table of Contents

Copies