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Document:	Firefox Workstation I/0 Cover Module Functional Specification
Order Number:	MISC-68363B1A
Revision:	0
Pages:	12
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OCR Text

Firefox Workstation 1/0 Cover Module
Functional Specification
Revision 1.2

Michael Nielsen (DECWSE: :NIELSEN)
Workstation Systems Engineering
Digital Equipment Corporation
100 Hamilton Avenue
Palo Alto, CA 94301
415-853-6679

December 23, 1987

RESTRICTED DISTRIBUTION

Copyright 1986, 1987 by Digital Equipment Corporation
The information in this document is subject to change without notice and should not be construed as a commitment by Digital Equipment Corporation. Digital Equipment Corporation assumes no responsibility for
any errors that may occur in this document. This specification does not describe any program or product
that is currently available from Digital Equipment Corporation. Nor does Digital Equipment Corporation
commit to implement this specification in any product or program. Digital Equipment Corporation makes
no commitment that this document accurately describes any product it might ever make.

Blank Page

Table of Contents

8. Firefox Workstation 1/0 Cover Module

8.1. EIA Driver and Receivers ................................................................................................

8.2. Keyboard and Mouse/f ablet Connector ...... .............. ............ ................... .......... .............

8.3. Modem Connector ...........................................................................................................

8.4. Pri.nter/Console Connector ...............................................................................................

8.5. Thin/fhick Switch ...........................................................................................................

8.6. ThickWire Ethernet Transceiver Connector ....................................................................

8.7. ThinWire Ethernet Transceiver .......................................................................................

8.8. Hexadecinlal-Digit Display .............................................................................................

8.9. -10-Volt Switchmode Power Supply ..............................................................................

8.10. Battecy ............................................................................................................................

8 .11. Firefox Workstation I/0 Module Connector .... ......... ..... .. ... .. ........ .. ....... ... .... ... .. ... .. .. ... .

8.12. Cover Module Printed Circuit Board .............................................................................

8.13. Power Requirements ......................................................................................................

8.14. Error Diagnosis ..............................................................................................................

iii

Blank Page

Revision History

Date
11Nov87

Version I Content/Change
1.2
Update references to DC-DC convener
Update
references to switcbmode power supply
I
Change 1/0 connector pin number assignments
Change specification for Ethernet switch
Miscellaneous edits

4 Jun 87

1.1

Changed to 5.2 by 8 PCB
Remove one hexadecimal digit and LED<7:5>
Added MFMDO to keyboard/mouse connector
Enhanced circuit descriptions

25 May 87

1.0

Changed ribbon-cable signal assignments
Changed key/mouse-connector signal assignments
Miscellaneous edits

27 Apr 87

0.0

Preliminacy draft

8. Firefox Workstation 1/0 Cover Module

This chapter is the functional specification for the Firefox workstation 1/0 cover module, which is part of
the Firefox workstation 1/0 cover assembly (H3061). The cover module connects to the Firefox wotkstation 1/0 module (L2003) via a 50-conductor ribbon cable and makes the ribbon cable signals externally
available as follows:
•

Keyboard and mouse/tablet serial lines on a 15-pin D connector

•

Modem serial line on a 25-pin D connector

•

Printer/console serial line on a 6-pin M:MJ connector

•

ThickWtre Ethernet transceiver line on a 15-pin D connector

•

ThinWire Ethernet tap on a BNC connector

•

Status outputs on a hexadecimal-digit display

A switch selects either ThickWire or ThinWire Ethernet output.
The cover assembly contains a battery for use by the I..2003 during power failures. The keyboard and
mouse connector also supplies +5-volt, + 12-volt, and -10-volt power for those devices.

The cover assembly consists of a 5.2-inch by 8-inch cover module that contains the connectors, serial line
DEC423/EIA-232-D driver/receivers, -10-volt switchmode power supply, and TbinWire Ethernet transceiver plus a battery and a metal cover plate.

8.1. EIA Driver and Receivers
The cover module implements the EIA driver, receivers, and transient absoiption required for the keyboard, mouse/tablet, modem, and printer/console serial lines. The EIA 5170/5180 driver and receivers are
in a DEC423/EIA-232-D compatible configuration, as specified by DEC STD 52-4. Both driver and
receivers have ESD/EOS protection circuitry. Receivers are biased and configured to failsafe to a high output in the event of powered-down peripherals, open circuit inputs, or shotted inputs.
The EIA driver bas a +/-10-volt supply to minimize power dissipation, which decreases junction temperatures and increases reliability. The +10-volt BIA driver supply is derived from the +12-volt cover module
supply through two series 0.975-volt, 1.0 ampere rectifier diodes. The -10-volt EIA driver supply is
derived from the + 12-volt cover module supply via a switcbmode power supply.
To minimiz.e etch length, and thus minimiz.e EMI and maximiz.e the effectiveness of the ESD protection
devices, the EIA driver and receivers are positioned adjacent to the serial connectors.

8.2. Keyboard and Mouse/Tablet Connector
Table 8-1 lists the signal assignments for the keyboard and mouse/tablet 15-pin, male, filte~ D connector. The manufacturing-mode input and status-display output signals are not connected to conductors in the
external cable; manufacturing-mode and stams-display signals are for use by manufacturing/field setvi.ce
with special loopback connectors.

8.2. Firefox Worbtation 1/0 Cover Module

December 23, 1987

FU'Cfox System Specification 1

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Table 8-1:

Keyboard and Mouse/Tablet Connector Pin Assignments

Source

Signal
GND

L2003

TXO

KEYBRD

4
5
6
7
8
9
10
11
12
13
14
15

L2003
L2003
MOUSE
L2003

RXO
+12V
+12V
RXl

Pin
1
2

TXl
GND
GND

MFMDl
L2003

LED4

MFMDO
L2003
L2003

+5.3V
-lOV
GND

Name
Keyboard ground
Keyboard transmitted data
Keyboard received data
Keyboard power
Tablet power
Mouse received data
Mouse transmitted data
Mouse ground
Keyboard power return
Manufacturing mode input
MSB of status display output
Manufacturing mode input
Mouse power
Mouse power
Mouse power return

The cover module uses a local LM317 regulator to regulate the +12-volt supply down to +5.3 volts for the
mouse power. A supply in excess of the nominal +5-volt L2003 supply is required to compensate for IR
drops in the external cables and current limit device. The cover module generates the -10-volt supply from
a switchmode power supply off its +12-volt input; it supplies +12 volts for the keyboard and tablet from its
own +12-volt supply. The nominal +12-volt output is in the range +12.46 volts to +11.59 volts.
The +12-volt keyboard supply is rated for a maximum of 300 milliamperes. The mouse +5.3-volt supply is
rated for a maximum of 160 milliamperes, the mouse -10-volt supply is rated for a maximum of 20 milliamperes, and the tablet + 12-volt supply is rated for a maximum of 300 milliamperes.
The mouse +5.3-volt supply output has a polymer PTC current limit device that changes from low
impedance to high impedance when the current exceeds 0.50 amperes. The mouse -10-volt supply output
bas a PTC device that trips if the current exceeds 0.50 amperes. The keyboard and tablet + 12-volt supply
outputs are current-limited by the L2003 if the total +12-volt current exceeds 1.75 amperes.
To ensure worst-case operation of the LK201 keyboard, VSXXX-AA mouse, and VSXXX-AB tablet, the
following conditions must be met The keyboard/mouse external cable power and ground conductors must
be a minimum of 20 AWG and a maximum of 15 feet. The external cable must have separate conductors
for each of the +12-volt and GND pins on the D connector. The keyboard/mouse external cable signal conductors must be a minimum of 24 A WG and have a minimum insulation thickness of 0.010 inches, a maximum capacitance of 35 picofarads per foot, and a maximum length of 15 feet. The contact resistance of
the D connector must be less than 0.030 Ohms. 1be contact resistance of the MMJ keyboard connector on
the remote end of the external cable must be less than 0.125 Ohms. The contact resistance of the DIN
mouse/tablet connector on the remote end of the external cable must be less than 0.030 Ohms.

If required for special applications, the keyboard/mouse serial lines can be up to 50 feet in length and still
meet worst-case signal margins for up to 9600-baud operation. (Nominal components should operate with
cables up to 500 feet in length.) 1be signal conductors must meet the conditions stated above. The special
cable must supply the keyboard and mouse/tablet with power from a power supply at the remote end.
For normal operation, the manufacturing-mode inputs must be unconnected To activate
manufacturing/field-service diagnostic modes, a loopback connector should short the MFMDO and/or
MFMD 1 pins to one of the GND pins on the connector. The LED4 output may be used as a status output
with Voh of 2.4 volts at 2 milliamperes and Vol of 0.5 volts at -10 milliamperes.

2 Firefox System Specification

Deccmbcr23, 1987

Firefox Workstation l/O Cover Module 8.3.

DIGITAL EQUIPMENT CORPORATION - RESTRICTED DISTRlBUfION

8.3. Modem Connector

Table 8-2 lists the signal assignments for the modem, 25-pin, male, filtered, D connector.
Table8-2:

Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

Modem Connector Pin Assignments

EIA
AA
BA
BB
CA

MODEM

RX2
RTS2
CTS2
DSR2
GND
CD2

CCITT
101
103
104
105
106
107
102
109

MODEM

SPDMI2

112

L2003

LLPBK2

141

L2003

DTR2

108/2

MODEM
L2003

RI2
DSRS2

125
111

MODEM

TMI2

142

Source

Signal

L2003
MODEM
L2003
MODEM
MODEM

TX2

cc
AB
CF

Name
Protective ground
Transmitted data
Received data
Request to send
aearto send
Data-set ready
Signal ground
Canier detect
Unconnected
Unconnected
Unconnected
Speed-mode indication
Unconnected
Unconnected
Unconnected
Unconnected
Unconnected
Local loopback
Unconnected
Data terminal ready
Unconnected
Ring indicate
Data signaling rate select
Unconnected
Test-mode indication

For operation up to 9600 bau~ the maximum cable length that meets worst-case margins is 50 feet. (Nominal components should operate with cables up to 500 feet in length.) The modem-cable signal conductors
must be a minimum of 24 A WG and have a minimum insulation thickness of 0.010 inches and a maximum
capacitance of 35 picofarads per foot.

8.4. Printer/Console Connector
Table 8-3 lists the signal assigmnents for the printer/console, six-pin, female, MMJ connector. An EMI
filter is located immediately adjacent to the MMJ connector.
Table8-3:

Pin
1
2
3
4
5
6

Prlnter/Coneole-Connector Pin Aulgnmenta

Source
L2003
L2003
L2003
PRNTR
PRNTR
PRNTR

Signal

co
TX3
GND
GND
RX3

Name
Control output
Transmitted data
Transmitted ground
Received ground
Received data
Control input

8.4. Firefox Work.station I/O Cover Modu.Jc

Decctnbcr23, 1987

FII'Cfox System Specification 3

DIGITAL EQUIPMENT CORPORATION - RESTRICTED DISTRIBtrrION

In accordance with DEC SID 52-4, the control-output signal is driven to a +5-volt level, and the control
input signal is terminated to gtound The control output cannot be modified by software, and the control
input is not accessible to software. To avoid inducing surges back onto the termination voltages, the control signals are attached to ESD protection devices.

For operation up to 9600 baud, the maximum cable length that meets worst-case margins is 50 feet. (Nominal components should operate with cables up to 500 feet in length.) The modem-cable signal conductors
must be a minimum of 24 A WG and have a minimum insulation thickness of 0.010 inches and a maximum
capacitance of 35 picofarads per foot

8.5. Thin/Thick Switch
The Thin!Thick switch selects between the internal ThinWrre Ethernet transceiver tap and the external
ThickWire Ethernet transceiver connection. The six-pole, double-throw switch connects the six differential Ethernet signals from the 1.2003 to the ThinWire or ThickWire logic.
The ThickWire D connector and the ThinWire BNC connector are positioned such that it is mechanically
impossible to simultaneously use both connections with proper cables.

8.6. ThickWire Ethernet Transceiver Connector
Table 8-4 lists the signal assignments for the ThickWrre Ethernet transceiver 15-pin, female, D connector.
The ThickWire Ethernet connection is compatible with existing Ethernet products and with the IEEE 802 3
Ethernet Specificaton. The control output is terminated to ground and cannot be modified by software. The
+ 12-volt supply is rated for a maximum of 500 milliamperes. The nominal + 12-volt output on the D connector is in the range + 12.46 volts to + 11.59 volts and is current-limited by the 1.2003 if cover module
+ 12-volt current exceeds 1. 75 amperes.
Table 8-4:

Pin
1
2
3
4
5

6
7
8
9
10
11
12
13
14
15

ThlckWlre Ethernet Transceiver Connector Pin Assignments

Source

XCVR
1.2003

XCVR
XCVR
XCVR
1.2003

XCVR
1.2003

Signal
GND
COL+
TX+
GND
RX+
GND
CTL+
GND
COLTXGND
RX+12V
GND
CTL-

Name
Shield
Collision presence
Transmit
Ground
Receive
Power return
Control output
Ground
Collision presence
Transmit
Ground
Receive
Power
Ground
Control output

The etch lengths of the differential Ethernet signals are matched to +/- 100 mils between the 1/0 module
connector and the isolation transformer. The traces are similarly matched between the isolation
transformer and the Thin/Thick switch, and between the Thin/Thick switch and the ThickWire D connector.
The external transceiver cable must conform to DEC SID 134.

4 Firefox System Specification

December 23, 1987

Firefox Workstation 1/0 Cover Module 8.7.

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8.7. ThinWlre Ethernet Transceiver
The cover module implements' a ThinWire Ethernet transceiver that can be connected to the ThickWrre
output from the 1..2003. The ThinWire transceiver, which is accessible through a BNC connector, which
consists of the DP8392 transceiver chip and associated passives, an isolation transformer, and a -9-volt
isolated supply. The isolated-9 volts is generated from the cover module +12-volt supply via a DC-to-DC
converter that utiliz.es a pulse-width-modulat~ fiyback switching-power supply.
The etch lengths of the differential Ethernet signals are matched to +/- 100 mils between the 1/0 module
connector and the isolation transformer. The traces are similarly matched between the isolation
transformer and the Thin/Thick switch, and between the Thin/Thick switch and the ThinWire Transceiver
chip. The stub length of the Transceiver chip input/output and BNC connector is less than 3 centimeters.

8.8. Hexadecimal-Digit Display
The cover module uses a single hexadecimal-digit display with two decimal points for the status output
display. 1be L2003 cable LED<3:0> signals cormect to the digit, and the LED<4> signal connects to the
left decimal point. The right decimal point is never illuminated. The display blanking control is configured
to always display.

8.9. -10-Volt Swltchmode Power Supply
The cover module implements a -10-volt switchmode power supply to generate the -10-volt supply it
requires for the mouse and EIA driver. The power supply is rated for a maximum output current of 250
milliamperes, with an efficiency of 60 percent

8.10. Battery
When the workstation is powered-off, the 1..2003 uses the cover assembly batteiy to maintain its time-ofyear clock and batteiy-backed-up RAM. This battery is a three-cell nickel cadmium batteiy pack that is
rated to supply 3.75 volts and has a capacity of 180 milliampere hours. The batteiy connects to the cover
module via a two-pin connector.

8.11. Firefox Workstation 110 Module Connector
Table 8-5 lists the signal assignments for the SO-conductor ribbon cable that connects the cover module to
the 1..2003.

8.11. Firefox Workstation 1/0 Cover Module

December 23, 1987

Firefox System Specification S

DIGITAL EQU1PMENT CORPORATION - RESTRICTED DISTRIBUTION

Table 8-6:

Firefox Workstation 110 Cover Power Requirements

Supply
+5V
+5V
+5.3V
+12V
+12V
+12V
+lOV
-lOV
-lOV
+9V

Amperes
0.18
0.25
0.16
0.30
0.30
0.50
0.10
0.10
0.02
0.18

Sink
Hexadecimal-digit displays
EIA receivers
VSXXX-AA mouse
LK201 keyboard
VSXXX-AB tablet
ThickWire transceiver
EIA driver
EIAdriver
VSXXX-AA mouse
ThinWire transceiver

8.14. Error Diagnosis
Hardware faults in the cover module can be diagnosed with loopback connectors for the serial lines and by
switching between the ThinWire and ThickWire connection for the Ethernet.
For the keyboard/mouse connector, the recommended loopback is jumpers from pin 2 (TXO) to pin 3
(RXO) and from pin 6 (RXl) to pin 7 (TXl ). For the modem connector, the recommended loopback is
jumpers from pin 2 (TX2) to pin 3 (RX2), from pin 4 (RTS2) to pin 5 (CTS2), from pin 6 (DSR2) to pin 20
(DTR2), from pin 12 (SPDI\tfi2) to pin 23 (DSRS2), and from pin 18 (LLPBK2) to pins 8 (CI2), 22 (RI2),
and 25 (TMI2). For the printer/console connector, the recommended loopback is a jumper from pin 2
(TX3) to pin 5 (RX3).

8.14. Firefox Workstation J/O Cover Modulc

December 23, 1987

FIJ'Cfox System Specification 7

DIGITAL EQUJPMENT CORPORATION - RESTRICTED DISTRIBlTI'ION

TableB-5:

1s~
+12V
I GND
TXO
CTS2
RTS2
TXl
DSR2
RI2
TX2
DSRS2
I SPDMI2
TX3
+5V
LLPBK2
-12V
MFMDO
LEDO
LED2
TX+
LED4
COL+
GND
RX+
GND
+12V

L2003 Cover Cable Signal Assignments

:1
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2

Pin
49
47
45
43
41
39
37
35
33
31
29
27
25
23
21
19
17
15
13
11
9
7
5
3
1

Signal

+12V
GND
RXO
GND
DTR2
RXl
GND
CD2
RX2
GND
TMI2
RX3
+5VBAT
GND
-12V
MFMDl
LEDl
LED3

TXSPARE
COLGND
RXGND
+12V

The I/0 connector and ribbon cable has -12-volt supply assignments for compatibility with future systems
that have a-12-volt power supply output; this will eliminate the need for the switcbmode power supply.
The cable is currently specified as a fiat, twisted-pair ribbon cable, with a maximum length of 6 inches.
The cable has 50 conductors that are specified to be not less that 28 A WG.

8.12. Cover Module Printed Circuit Board
The cover module printed circuit board is a 5.2-inch by 8.0-inch fingerless circuit board (El.EN 622-06). It
is a four-layer board with two outer signal layers, a split power layer, and a split ground layer, all in 1ounce copper (El.EN 630-07). The power layer is split between +5 volts, + 10 volts, + 12 volts, -9 volts,
and -10 volts. The ground layer is split between frame ground and the isolated ground for the Ethernet
transceiver circuit The signal etch is 12/13 technology with uncontrolled impedance (GDC
DD23AAXXXX).
The nonisolated ground layer functions as a frame ground and is electrically connected to the external connector shells/shields and cover plate. The ground layer connects to the system logic ground through the
ribbon cable.

8.13. Power Requirements
Table 8-6 summarizes the power requirements for the cover assembly. The worst-case power consumption
is 0.43 amperes at +5 volts and 1.26 amperes at +12 volts from the I..2003. The cover module itself dissipates a maximum of 9 .1 watts.

6 Firefox System Specification

December 23, 1987

Ftrefox Workstation l/O Cover Module 8.13.