North Star MDS-A-O User manual

MICRO-DISK SYSTEM MDS-A-D
DOUBLE DENSITY
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NorthSbrCompumlnc
2547 Ninth Street
Berkeley, Co. 94710
Table of Contents
Introduction. ..... •
Cautions . . . . . .
Limited Hardware Warranty
Out of Warranty Repair . .
Limited Software Warranty
Software License . . . • .
Parts List ........
Assembly Information • • .
Figure lA: Identification of Components
Assembly and Check-out Instructions
System Integration . • • • . . . .
Theory of Operation •••••
Appendix 1: Pulse Signal Detection
Schematic Drawings • • . • • • . •
Copyright 1978, North star Computers, Inc.
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MDS-D
REVISION 2
25010

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INTRODUCTION
The North Star Micro-Disk System (MDS-A-O) is a complete floppy
disk system for use with 5-100 bus computers. The system
includes the disk controller board, one floppy disk drive, power
regulation, cables, software and documentation. The software is
provided on diskette and includes the North Star Disk Operating
System, BASIC Language System, Monitor, and various utility
programs. The system is capable of controlling up to four disk
drives. Each disk drive can record 179,200 bytes of information
on a diskette, thus allowing up to 716,800 bytes of on-line disk
storage. Addition disk drives, AC power supplies, and cabinets
are available as options
If you have purchased the MDS-A-D as a kit, then first skim the
entire manual. Be sure to carefully read the Assembly
Information section before beginning assembly. If you have
purchased the MDS-A-D in assembled form, you may skip the
Assembly section.
CAUTIONS
1. Correct this document from the errata before doing anything
else.
2. Do NOT insert or remove the MDS controller from the computer
while the power is turned on.
3. Do NOT insert or remove Ie's from the board while the power is
turned on.
4. Be sure the +5 volt and +12 volt regulators are generating the
correct output voltages before installing any IC·s.
5. Be careful to insert all IC's in correct positions and with
correct orientation.
6. Do NOT connect or disconnect, mount or dismount, or in any way
physically tamper with the disk drive, power board, or disk
controller while the power is turned on.
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In some cases disk drives may not operate properly if located
in the vicinity of TV'S, electric motorS, or other sources of
electrical noise. This may be remedied by moving the disk
drive away from the noise source or by installing the disk
drive in a grounded cabinet.
North star MICRO-DISK System 2

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LIMITED HARDWARE WARRANTY
'~'North Star Computers, Inc. warrants the electrical and mechanical
: ; parts and workmanship of this product to be free of defects for a
{,. period of 90 days from date o"f purchase. If such defects occur, ,'I
.t' North Star Computers, Inc. will repair the defect at no cost to
;'~-.: -the purchaser. This warranty does not extend to defects
(ixesulting from improper use or assembly by purchaser, not does it
~~over transportation to the factory. Also, the warranty is
~'invalid if all instructions included in the accompanying
.~ documentation are not carefully followed. Should a unit returned
~·<·.·.for warranty repair be deemed by North Star Computers, Inc. to be
;. defective due to purchaser's action, then a repair charge not to
jl~~·exceed $30 without purchaser's consent will be assessed. ANY
'UNIT OR PART RETURNED FOR WARRANTY REPAIR MUST BE ACCOMPANIED BY
. :A COPY OF THE ORIGINAL SALES RECEIPT. This warranty applies to
·.:units located outside the United States of America only if all
~·:·costs and arrangements for transportation of the product to and
'~~ from the factory are borne entirely by the customer. This
tlwarranty is made in lieu of all other warranties, expressed or
t:-::. implied, and is limited to the repai~ or. repl~cement of the
~!... product. No warranty, expressed or 1mpl1ed, 1S extended
~ concerning the completeness, correctness, or suitability of the
.~ North Star equipment for any particular application. There are
!:: .... no warranties which extend beyond those expressly stated herein •
. ~
OUT OF WARRANTY REPAIR
,If your unit is out of warranty and you are unsuccessful at
;diagnosing or repairing the problem, out-of-warranty service may
'.be arranged with a local dealer or other experienced local
)computer technician. Alternatively, any North Star products may
<be shipped PREPAID to the North Star address with a clear written
~escription of the problem. Include as many details as possible
about the problem and about your system configuration. Your unit
'will be returned, C.O.D., within 30 days after receipt by North
Star. Out-of-warranty repair service is billed at the rate of
$25.0~ per hour. If you wish to place an upper limit on the
:amount of time spent on your unit, mention this in the written
description.
North Star MICRO-DISK System
.,

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LIMITED SOFTWARE WARRANTY
The following limited warranty applies to the North Star BASIC,
DOS, and Monitor software delivered on diskette with the MICRO
DISK SYSTEM.
North Star Computers, Inc. warrants that a copy
identical to the North star master copy of the software has been
stored on the customer diskette and can be read into computer RAM
memory from the diskette by a properly functioning MICRO DISK
SYSTEM using the North Star disk controller board and disk drive.
If a diskette malfunctions and has not been damaged by the
customer and has not been operated with the write-protect tab
removed, then North Star will re-write or replace the diskette if
it is returned to North Star, prepaid, within three months from
date of purchase.
No warranty, expressed or implied, is extended concerning the
completeness, correctness, or suitability of the North Star
software for any particular application. No consequential damage
resulting from use of the software is covered - this warranty is
limited to the repair or replacement of the original software
diskette.
SOFTWARE LICENSE
The North star BASIC, DOS and Monitor are copyrighted products of
North Star Computers, Inc., and are included with the MICRO DISK
SYSTEM
under the following license agreement:
The software may be used in conjunction with the North Star
HORIZON computer and North Star MICRO DISK SYSTEM only. The
customer may make copies of the software for convenience of use,
as long as the North Star copyright notice is preserved with each
copy. This license specifically prohibits use of the software in
a computer which does NOT include a North Star disk controller
board, and also specifically prohibits modification of the
software for use in any system which does not contain a North
Star disk controller board.
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North Star MICRO-DISK System
4

PARTS LIST
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MDS SYSTEM PARTS
.
disk drive, Shugart SA-4e0 (double density)
ribbon cable assembly
diskette, blank
diskette, pre-recorded with software
MDS-D Manual
System Software Manual
OEM Manual
HDS controller with parts
MDS power board with parts
North Star name plate
9 MDS CONTROLLER PARTS
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74LS241
74LS253
74LS257
74LS273
74LS393
7404
7438
74166 or 74LS166
DWE PROM (6301 or 82S129)
DSEL PROM (6301 or 82S129)
DPGM PROM (63091
LF356
3080
3
2
1
1
3
1
3
1
1
1
1
1
1
North Star MICRO-DISK System
printed circuit board (Sit x 10"), HDS-AD
20-pin Ie sockets
16-pin Ie sockets
14-pin Ie sockets
34-pin cable connector header
crystal, 4MHz
IN4148 diodes
+5 volt regulators, 7805 or 340T-S
+12 volt regulator~ 78L12
heat sinks, 6107B-14
6-32x3/8'· machine Screws
#6 lock washers
6-32 nuts
74LS00
74LS02
74LS08
74LSIr
74LS14
74LS32
74LS74
74LS109
74LS123
74LS138
74LS161
74LS164
74LSl74
2
",1
1
.1
2
1
.6
3
3
1
4
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:Integrated Circuits
.. ---~---.- 1
i'!' 5
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": 6
"2
1
2
"2
C2
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MDS POWER BOARD PARTS
Capacitors
2.2Uf
6.8uf
.01uf
.022uf
.047uf
33pf
100pf
200pf
330pf
470pf
47pf
100pf
330pf
.047uf
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•
ohm 1/4W 5%
ohm 1/4W 1%
ohm 1/4W 5%
ohm 1/4W 5%
ohm 1/4W 5%
ohm 1/4W 5%
ohm 1/4W 5%
ohm 1/4W 5%
5.6K
6.19K
6.8K
9.1K
10K
13K
15K
27K
3
1
2
1
1
1
1
3
tantalum
tantalum
dipped mylar 10%
di?ped mylar 10%
dipped mylar 10%
dipped mica 5%
dip1?ed mica 5%
dipped mica 5%
dipped mica 1%
dipped mica 5%
ceramic disk 20%
ceramic disk 20%
ceramic disk 20%
ceramic disk
1/4W 5%
1/4W 5%
1/4W 5%
1/4W 5%
1/4W 5%
1/4W 5%
1/4W 5%
1/4W 5%
ohm
ohm
ohm
ohm
ohm
ohm
ohm
ohm
3 • 3
150
330
470
680
2.2K
3.3K
3.6K
Resistors
4
2
1
3
1
1
1
2
2
1
1
1
1
18
1
5
1
4
2
3
>1
1
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1
2
1
1
1
1
3
3
3
1
4
1
1
2
2
1
printed circuit board, 3" x 5 1/2"
capacitors, .047uf ceramic disc
regulator, 7805 or 340T-S
regulator, 7812 or LM340-12
heat sink, 60308
heat sink, 690-3-8
machine screws, 6-32x3/8"
lock washers
nuts, 6-32
power plug
power plug pins
4 conductor power cable, 5 feet
strain relief bushing
machine screws, 6-32xl 1/4"
spacers
ground wire with terminals, 5 feet
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North Star MICRO-DISK System
6

.' POWER SUPPLY PARTS (MDS-PS option)
I
~ 1
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({I
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i .~; 2
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115v cord set, 8 feet
strain relief bushing
fuse holder
fuse, lA 3AG
toggle switch
transformer
capacitor, 3000uf 30wvdc electrolytic
capacitor, 3500uf 15wvdc electrolytic
rectifier diodes, MR501 3A
rectifier diodes, IN4002 lA
machine screws, 6-32x3/8,r
lock washers
nuts, 6-32
hook-up wire
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". CABINET PARTS (MDS-CAB option)
cabinet base plate
cabinet cover
stick-on rubber feet
6-32 flat head screws
6-32 pan head screws
7 North Star MICRO-DISK System

ASSEMBLY INFORMATION
Read completely through each section before beginning the first
instruction step of that section. Perform all operations in the
sequence indicated. Read each step entirely, including any notes
that accompany the step, before beginning to follow the step.
WORK AREA AND TOOLS
Start with a clean, well-lit and well-ventilated area to work.
The area should be large enough to accommodate the kit, tools,
parts and assembly instructions. Suggested tools are:
screwdrivers, needle-nose pliers, diagonal cutters, soldering
iron, solder, and masking tape. Anumber of tests will require
using aYOM (ohmmeter-voltmeter), or VTVM. Also highly
desirable, but not necessary, are an Ie inserter, a screw-holding
screwdriver, an oscilloscope or logic probe, and an extender
card. [Note that if you do not have an oscilloscope or logic
probe, waveforms can be detected by one of the procedures
described in Appendix 1.1
SOLDERING TIPS
Par best results use a 15 to 25 watt soldering iron or an iron
with a temperature controlled tip (approximately 700 degrees) •
• The tip should be no wider than the solder pads on the printed
circuit board. Use only a fine gauge rosin core solder (60/40 or
63/37). Do NOT use acid core solder as this can severely damage
a printed circuit board. When soldering, keep the soldering iron
tip on the pad just long enough for the solder to completely
flow. If the solder does not draw up the wire then more solder
is required. Do not use so much solder that it overflows the
pad. If a solidified joint is not shiny, it may be a cold solder
joint and should be remelted. The soldering iron tip should be
cleaned frequently by wiping on a damp sponge
When you have completed assembly of a board, inspect it for
unintended solder connections or "bridges", as well as unsoldered
leads. After soldering, it is recommended that the rosin flux be
removed from the board using flux remover, FREON or paint-thinner
type solvent. This will make looking for soldering problems
easier and give the board a clean, professional appearance.
IC SOCKET INSTALLATION
Integrated circuit (IC) sockets can be installed by first
inserting them into the printed circuit board, then placing
another flat board over the Ie sockets and finally turning over
this sandwich. Be sure that each IC socket is inserted into the
proper location and is oriented such that pin 1 of the socket
~corresponds to the pin 1 indication.on the PC board layout
legend. (Refer to figure lA to identify pin 1 on an IC socket.)
To solder Ie sockets, first solder just two opposite corner pins
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North Star MICRO-DISK System 8

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for all sockets being installed. Then remelt the corner
connections while applying pressure down on the board. This will
remove any gaps that may be present between the IC sockets and
the PC board. Finally, solder the remaining pins of the IC
sockets.
RESISTOR AND CAPACITOR INSTALLATION
DIP HEADER SOLDERING
North Star MICRO-DISK System
9
pin numbering conventions for the 8-100 edge pins are as follows:
When viewing the component side of the board (with the pin edge
facing down), pins 1,2, ... , 50 range from left to right. When
viewing the solder side of the board, pins 100, 99, .•. , 51 range
from left to right.
The white component layout legend is printed on the component
side of a printed circuit (PC) board. All components are
inserted from this side (component side) and soldered on the
other side (solder side). Locations on the PC board are
identified by. two-character codes as marked on the board: a digit
followed by a letter indicating the horizontal and vertical
coordinates of the location. Note that in North Star kits, IC's
can be found on styrene padS in positions corresponding to their
intended locations on the PC board.
PRINTED CIRCUIT BOARD LAYOUT
To install resistors or capacitors, first make right angle bends
in the leads to fit the PC board hole spacing. (Some capacitor
leads are already appropriately spaced and do not need bending.)
Then insert the leads as far as possible through the correct
holes in the PC board and spread the leads slightly on the solder
side of the board to keep the part in place. After a group of
resistors or capacitors has been inserted, then solder the leads
on the solder side of the board and snip off the excess leads as
close to the board as possible. Use caution to avoid eye injury
from flying bits of wire. Save the lead clippings for later use
in making jumper connections.
When making jumper connections on aDIP header, solder resistor
or capacitor lead snippings between the leads to be connected.
When more than two pins are to be connected together, bend a
single wire so that it routes to each pin, and solder each pin
,once. Insert the header in an IC socket on a PC board to hold it
during soldering. Overheating the pins with the soldering iron
will melt the plastic of the header. If there are multiple
jumpers on a header, make sure that no unintended connections are
made by carefully routing the jumpers, or by insulating each
jumper with some wire insulation.
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+
+
+
-
Resistor Network
Regulator (To-220)
)
Pin 1 ---P"
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.047 )
Axial lead
ElecHolytic Capacitor
Resistor
,
Transistor and
Regulator (To-92l
<·========0100MFO)
positive (+1 lead \.};... .
Quick-Connect
Lug
Ceramic
Disc
Capacitor
Dipped
Mylar
Capacitor
Dipped
Mica
Capacitor
Dipped
Tantalum
Capacitor
,
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Integrated Circuit {Ie}
IC Socket
DIP Header
Figure lA. Identification and orientation of components.
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ASSEMBLY AND'CHECK-OUT INSTRUCTIONS
DISK
CONTROLLER BOARD ASSEMBLY
For best results, assemble the MDS controller using the following
steps.
Similarly, install the 22 fourteen-pin IC sockets.
Similarly, install the 19 sixteen-pin IC sockets. A
sixteen-pin socket is used at location lAo The two 8-pin
IC's will be inserted into this socket.
Insert and solder the 5 twenty-pin IC sockets at locations
70, 80, 90, 100, and 110, following the procedure given in
the Assembly Information section. Orient them as shown on
the layout legend with pin 1 toward the bottom of the board.
AL
NOTE: Orient the board with the edge connector toward you and the
heat sink area to the left. The component side is now up. The
silk screen legend is on the component side.
ct, A2.
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A4. Install and solder the 31 resistors in the locations
indicated by the layout legend. The hole spacing for all
the resistors is .5 inches.
North Star MICRO-DISK System
11
Resister
( ) Rl
( )
R2
( ) R3
( ) R4
( ) R5
( ), R6
( ) R7
( ) RB
( ) R9
( ) RiB
( ) Rll
( ) R12
( ) R13
( ) R14
( )
R15
( ) R16
( ) R17
( ) RiB
( ) R19
Location
lA
lB
lB
2A
2A
2B
2B
2B
3A
3A
3A
3A
3C
3C
3C
3C
4B
14A
4A
Value
3.3K
3 • 3
5.6K
27K
27K
5.6K
6.19K
2.2K
47B
47B
5.6K
3.6K
6.BK
13K
27K
6.BK
2.2K
6BB
9.1K
Size
1/4W
1/4W
1/4W
1/4W
1/4W
1/4W
1% 1/4W
1/4W
l!4W
1/4w
1/4W
1/4W
1/4W
1/4W
1/4W
1/4W
1/4W
1/4W
1/4W
Color-code
erg-org-red
org-org-gld
grn-blu-red
red-vio-org
red-vio-erg
grn-blu-red
blu-brn-wht-brn
red-red-red
yel-vio-brn
yel-vio-brn
grn-blu-red
org-blu-red
blu-gry-red
brn-org-erg
red-vio-org
blu-gry-red
red-red-red
blu-gry-brn
wht-brn-red

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Type Location Value Capacitor
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( ) R20 5A 10K 1/41'1 brn-blk-org ,
( ) R21
50 470 1/41'1 yel-vio-brnt
( ) R22 6A 15K 1/41'1 brn-grn-org l
( ) R23 60 2. 2K 1/41'1 red-red-red':
( ) R24 60 330 1/4W org-org-brn ,.;~:
l l ~~~ ii~ ~~~ ij ~~ ~~~=~~;;=~;~ >t<;
( 1 R27 12A 150 1/41'1 brn-grn-brn
( 1 R28 12A 15~ 1/41'1 brn-grn-brn; J
( ) R29 12A 150 1/41'1 brn-grn-brn "
( ) R30 14A 150 1/41'1 brn-grn-brn ,t~
Inser~ ~n:3:o1de/::e 39 capa:::ors in 1~:: 10ca:::::rn-brn,.jj
,,
indicated by the layout legend. The tantalum capacitors I
have polarity, so care must be taken to insert the positive _~::_:;
lead in the hole marked with a plus sign. The "+~ lead of
tantalum capacitors is marked with a"+" sign. Some 1;
capacitors are marked with a 3-digit code consisting of two ~
significant digits followed by a power of ten expressed in .1:
picofarads. Thus, 223 means 22lHHlpf or .022uf and 331 means -.~:
330pf. These alternate capacitor markings are given below ~;
in parentheses after the capacitor value. '
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( ) Cl
( ) C2
( ) C3
( ) C4
( 1 C5
( 1 C6
( ) C7
( ) C8
( 1 C9
( ) C10
( ) Cll
( ) C12
( ) C13
( ) C14
( ) C15
( ) C16
( ) C17
( 1 C18
( ) C19
( ) C20
( ) C21
lC
lC
10
10
20
20
lA
18
lC
2A
28
3C
38
38
4A
5A
50
50
118
15A
15A
6.8uf
2.2uf
6.8uf
2.2uf
2.2uf
2.2uf
.047uf(473)
100pf(101)
.022uf(2231
.01uf(1031
330pf (331) 1%
200pf(201)
.022uf (223)
200pf(2011
330pf(33111%
.022uf(223)
330pf(331)
47pf
100pf(1011
33pf
470pf(471)
tantalum
tantalum
tantalum
tantalum
tantalum
tantalum
dipped mylar
dip?ed mica
dipped mylar
dipped mylar
dipped mica
dipped mica
dipped mylar
dipped mica
dipped mica
dipped mylar
ceramic disc
ceramic disc
ceramic disc
diT?ped mica
dipped mica
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The remaining eighteen .047uf(473) or .05uf(5~3) ceramic
disc capacitors are bypass capacitors and should be
installed In the oval capacitor locations marked with
asterisks (*) on the layout legend.
North Star MICRO-DISK System
12

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A6.
Insert and solder the six IN4148 diodes at the loc3tions
indicated -by the layout legend. The end of the diode marked
with a band is the cathode end and must be oriented as
indicated by the layout legend.
-.
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Diode Location Orientation
(1 2A band at left
(2
2A band at right
(3
2A band at left
(4 2A
band at right
(5
3A band at right
(6
3A band at left
North Star MICRO-DISK System
Be sure the power is off and then plug the disk controller
board into a computer motherboard 100-pin connector. Be
sure the board is properly seated in the connector and then
turn on the power. Check for +5 volts ±5% (with reference
to the ground plane at the left of the board) at 3C pin 16
and at 2C pin 14. Check for +12 volts ±5% at location IA at
pin 7 of both the LF356 and the 3080. Turn off the power
and remove the disk controller from the motherboard.
NOTE: Heat sink grease may be used though it is not
generally needed. Don't tighten the machine screw too tight
or you will crack the PC board.
Install each of the two heat sinks and 5 volt regulators at
locations Ie and 1D as follows. Bend down the three leads
of the 5 volt regulator 90 degrees such that the leads go
into the correct holes while the machine screw holes line
up. Don't solder yet. Fasten the heat sink and regulator
to the PC board so that the following sequence results from
bottom to top: 6-32 machine screw head, PC board, heat sink,
regulator, lock washer, and nut. Tighten the machine screw.
Now solder the regulator leads.
Insert and solder the crystal at location 15A. Bend the
leads so that the crystal will lie parallel with the PC
board. In addition to the two leads, the crystal should be
strapped to the PC board with a piece of clipped resistor
lead which is soldered to the pads on either side of the
crystal case.
13
All.
Install the 12 volt 78L12 regulator (Q3) near location 28,
orienting the regulator so that the flat edge corresponds to
the flat edge indicated on the layout legend.
:A10. Install arid solder the 34-pin cable connector header (J2).
The right angle bent pins should be 4nserted into the PC
board and the straight ends of the pins should be pointing
toward the top of the board.
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The labels on the PROM"s for the standard version #1 are
OWE-I, DSEL-E8-1, and DPGM-ES-l.
PROM Label
OWE-y
DSEL-xx-y
DPGM.-xx-y
Type PROM
6301
6301
6309
indicated, locate and correct the
HEX digits of PROM origin
Location
4C
llC
90
was not as
going on.
Name
xx=two high order
y =version number
Layout
OWE
OSEL
OPGM
If the vol tage
problem before
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A12. Install all 47 Ie's in the locations indicated on the layout,-i'
legend, being careful to use the correct orientation. All Ji
the Ie' s should be or iented the same way, with pin 1 toward 1,
the bottom. Be sure all the Ie pins are in the socket holes\l
and not bent under the IC and,not outside the socketol
The three PROM 5 can be identified as follows: -<;'
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p
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I '-.../
The disk controller board is now completely assembled. Proceed
to the checkout section.
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North Star MICRO-DISK System
14

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DISK CONTROLLER BOARD CHECKOUT
The following terms are used in specifying expected test results:
The following checkout procedure may be followed for a newly
assembled board. However, you may choose to skip this section
and return to it later only·if the disk controller does not see~
to be operating correctly. It can also be used to diagnose
problems in previously operational boards.
When referring to the name of a signal from the schematic
drawings, if the signal is identified with a bar over its name,
then the name is followed by a slash (e.g., STORE/) in the
checkout instructions. When describing an AC pulse, the notation
(±W,P) refers to a positive or negative pulse with a width of W
appearing with a period of P. For example, a positive pulse with
width l2e nanoseconds appearing every 25 microseconds would be
described as (+l20ns,25us) See Appendix 1 for details on how to
detect pulse signals.
ground, e volts DC
logic zero, 0-.7 volts, normally about .3 volts
logic one, 2.4-5.0 volts, normally about 3 volts
+5 volts from power supply
Signal with pulses (as opposed to DC signal)
GND
LOW
HIGH
+5V
AC
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AC, 500ns square wave
AC, 8us square wave
AC, 128us square wave (some jitter)
AC, 2ms square wave (some jitter)
AC, 32ms square wave (some jitter)
AC, 500ms square wave
AC, 8.3sec square wave
AC, (+S.3sec,33sec)
DESCRIPTIONLOCATION
15B pin 12
6A pin 11
7A pin 11
SA pin 11
9A pin 11
15C pin 6
3D pin 6
6C pin 11
SIGNAL
LCLK!
CC3
CC6
CCll
CCl5
SC03
(no name)
AUTO-OFF
Cl. with the computer power off, install only the disk
controller board into the motherboard. The ribbon cable
should not be plugged into the board. Turn on the computer
power and check for the following counter timing signals:
If an oscilloscope will be used to test the board, a ~scope
ground" may be installed by soldering a "bridge" of jumper wire
between the two PC board holes that connect edge connector pins
53 and 100 near location 12D. Note that either of the two
regulator machine screws can also be used for ground test points.
If the signals are not as listed then refer to the schematic
drawings and trace backwards to locate and correct the
'f' problem.
15
North Star MICRO-DISK System

E.
Check the following signals while
the computer reset switch
is depressed
(hold depressed with
a
rubber band) :
SIGNAL LOCATION DESCRIPTION
WR-SHIFT/ 60
pin
6AC,
(-lus,Sus)
LD-WSR/
60 pin 15 AC, (-8us,64us)
WS7
60 pin 13
AC·,
(-96us,32ms) i.e.
mostly
HIGH
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WS10 5C
pin
15
AC, (-96us,32ms) i.e.
mostly
HIGH
WRITE PULSE
3C
pin
5AC,
(+approx 600-700ns,4us)
(no name)
3C pin 13 AC, (+approx 600-700ns,4u5)
READ DATA
l4B pin
12
AC, (+approx 600-700ns,4us)
A. with the computer power off, remove the disk controller
board from the motherboard.
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a clip lead between cable connector (J2) pin 22 and
If you do not have a clip lead, then tack solder a
the solder side of the hoard hetween 138 pin 11 and
13.
D. with the computer power off, install only the disk
controller board and the processor board into the
motherboard, and turn the computer power on.
C. Connect
pin 30.
wire on
148 pin
B. Remove the 74LS74 IC from location 14C, bend out pin 9 of
the IC, and re-insert the IC so that pin 9 is outside the IC
socket and does not make contact with IC socket pin 9.
C2. This step will check the write circuitry while simulating
writing a continuous stream of ~one" data bits in single-
density format during each sector.
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SIGNAL LOCATION DESCRIPTION
~-
WINDOW 13C
pin
9
"Window", HIGH for
96us then LOW
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RE
58 pin 6
"Read
Enable", goes HIGH
at
480us
•,
ACQUIRE
5A pin 5"
Acquire
Phase of
Incoming Signal",
goes
HIGH with RE,
duration 100-150u
If the signals are not as listed then refer to the schematic
drawings and trace backwards to locate and correct the
problem.
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C3. This step will check the read circuitry while simulating
reading a continuous stream of zero" data bits in double-
density format during each sector. If using a scope to
check signals then sync positive on 13C pin 9. Continue
with the same setup as in the previous step. Check the
following signals while the computer reset switch is
depressed.
North Star MICRO-DISK System
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2BR 3B pin 5 "Twice Bit Rate~, low at first,
4us square wave for 32u5 when RE
goes high, then 2us square wave
A. Remove the 74LS74 IC at location 40, lift pin 9 of the IC,
and re-insert the IC so that pin 9 is not inserted in the Ie
socket. Then, with the computer reset switch depressed,
check of the following signals:
North Star MICRO-DISK System
B. Re-insert the pins of the IC's at locations 14C and 40 into
their IC sockets and remove the clip lead or soldered wire.
pulse beginning at 7~~us,
duration 3S-5~us
DESCRI PTION
Goes HIGH at 780us
LOW
May begin either HIGH or LOW,
then 4us square waves after RE
"Read Shift Register", all
outputs always LOW
"separated Data", always LOW
except for 8 extremely narrow
pulses at ACQUIRE
See Note 1.
"Hunt Enable", goes HIGH at 736u5
"Double-Density Indicator~,
goes HIGH at 512us (32u5 after RE)
5B pin 10
1B pin 13
LOCATION
58 pin 10
150 pins 3,4,5,
6,10,11,12,13
SYNC BLANK
BODY
SIGNAL
Note 2: The two op-amp {LF356} inputs are very high
impedance and attempts to obseve them with a scope probe can
affec·t the circuit.
Note 1: Initializes during WINDOW by slewing to +5 volts.
During ACQUIRE there will be numerous small positive or
negative pulses (phase corrections). A DC shift of less
than 1/4 volt may be seen at this time if a frequency
adjustment occurs. The resultant DC level should remain
until the next WINDOW pulse.
BODY
RSn
DOl
4B pin
9
HE
14C pin
5
OP-AMP-OUTPUT Right
side
R7
DATA WINDOW
40 pin
5
WIND DATA 40 pin
9
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DIS~ CONTROLLER CONFIGURATION OPTIONS
There are anumber of configuration options possible on the disk
controller board that are specified by wiring jumpers on the
board. The desired configuration should be wired according to
the following instructions before the board is used.
Jl. Signal grounding. The "Gil jumper below location 5D ia
normally installed when the disk controller is used in a
HORIZON. If the disk controller is to be used in another S-
100 bus computer, then the 11G,j jumper should be installed
only if motherboard signal 61 is used as ground in that
computer.
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Connect 2 to 1
Connect 2 to 1
Connect D to 1
Connect 2 to 1
Connect D to 1
Connect C to 1
Connect 2 to 1
Connect 0 to 1
Connect C to 1
Connect B to 1
SECOND JUMPER FIRST JUMPER
Connect 0 to 3
Connect C to 3
Connect C to 2
Connect B to 3
Connect B to 2
Connect B to 2
Connect A to 3
Connect A to 2
Connect A to 2
Connect A to 2
3.2 seconds
6.4 seconds
9.6 seconds
12.8 seconds
16.0 seconds
19.2 seconds
25.6 seconds
28.8 seconds
32.£1 seconds
38.4 seconds
DELAY TIME
Secto~ Interrupts. The disk controller board includes logic
which can cause an interrupt to occur each time a sector
hole is detected on a diskette. Normally, this logic is
disabled. To use this logic, connect ajumper wire below
location 40 on the component side of the PC board which
connects' "y" to the position for the type of interrupt
desired (VIO/ to PINT/).
J3.
J2. Automatic motor off time. Normally, the disk drive motor(s)
will turn off 9.6 seconds after the last disk activity. If
some other automatic motor off delay time is desired, then
cut the traces at location 20 on the solder side of the PC
board which connect "C
01
to"2" and "011 to "1". Then connect
two jumper wires on the component side of the PC board at
location 2D according to the following table:
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North star MICRO-DISK System
18
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POWER BOARD ASSEMBLY
There are three different ways that power can be supplied to a
disk drive •
a. Direct hook-up of regulated +5 volts and +12 volts from an ~
existing regulated power supply. In this case the Power PC
Board is not used and the four conductor power cable should be
connected directly to the power plug as described in Step PS
below. The other end of the power cable should be connected
to the corresponding outputs of the regulating power supply.
,b. Use the Power PC Board to regulate power Tram an existing
unregulated power supply. The power supply in many 5-100 bus
computers is adequate to power one drive. In general, compare
the disk drive power requirements against the power supply
capacity to see if this arrangement will work. If this power
supply option is to be used then follow the instructions below
starting at Step Pl.
c. Use the North Star Power Supply option (MOS-PS). The MDS-PS
provides all the components needed to obtain unregulated power
from a 115 volt AC line. Some of the MDS-PS parts mount on
the Power PC Board and some mount to the North Star MICRO-DISK
Cabinet (MOS-CAB) or elsewhere. If this option is used then
start assembly with Step PI below and continue with the MDS-PS
assembly instructions.
The silk screen legend is on the component side of the PC board
and the traces are on the solder side.
Pl. Bolt the +5 volt regulator (7805 or 340T-5) to the inside of
the 6030B heat sink so that the following sequence results
from top to bottom: 6-32 machine screw head, heat sink,
regulator, lock washer, and nut. The regulator leads should
point the same direction as the heat sink mounting posts.
P2. Install the regulator heat sink assembly by inserting the
regulator leads in the correct holes on the PC board and
then inserting the heat sink mounting posts in their holes.
Now solder the regulator leads.
p3. Mount the 690-3-B heat sink and 7812 regulator on the PC
board such that the following sequence results from back to
front: 6-32 machine screw heads, PC board, heat sink,
regulator, lock washers, and nuts. Two machine screws are
required to mount this regulator. Position the heat sink as
far from the edges of the PC board as possible and tighten
the machine screws. Now solder the two regulator leads.
P4. Assemble the disk drive power plug as follows. Cut off a
piece of 4-conductor power cable about 3 inches long.
Remove an inch of outer insulation from both ends. Strip
19 North Star MICRO-DISK System

1/4" of insulation from each conductor at both ends. Crimp
and
solde·r eaeh of the four power plug pins to the
conductors at one end. Finally, insert the power plug pins
into the power plug using the following color code: +5 red,
+12 green, ground black and white. Consult the OEM Manual
(sections 4.2 and 5.2) for the correct connection of power
to the power pins.
P5. solder the four wires coming from the power plug assembly to
the appropriately labeled holes in the lower righthand
corner of the. PC board. The wires should be inserted into
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NOTE: If the MDS-PS power supply is being used, then skip
the remaining steps of these instructions and go on to the
MDS-PS assembly instructions.
P6. Insert and solder the two .947uf ceramic disc capacitors (Cl
and
C2) in the locations indicated by the silk screen
legend.
P7. The four wires in the 5-foot power cable should be soldered
to the four holes in the PC board labeled 8v, 8v, 9v, and
l8v using the following color code: 8v black, Bv white, 9v
red, l8v green. The wires should be inserted into the PC
board from the component side.
pa. Connect the other end of the power cable to the appropriate
power points-of the unregulated power supply. For example,
the cable can be connected to the power pins at an unused
position on the S-100 bus mother board. Consult the
computer reference manual for details. If the disk drive is
to be mounted inside a cabinet (MDS-CAB) then the power
cable should be passed through a hole in the back of the
cabinet and clamped with the provided strain relief bushing
before connection to the power source.
P9. Check that the regulators are providing +5 and +12 volts at
the proper power plug pins before plugging into the drive.
_--!,ll. Mount· the PC board to the back of the disk drive as follows.
Carefully remove the two machine screws that mount the small
PC board to the back of the disk drive. Save the quick-
connect lug and lock washer from the righthand (as seen from
the back of the disk drive) mounting screw. Use the two
longer machine screws and spacers so that the following
sequence results from back to front: machine screw head,
(quick-connect lug and lock washer on righthand screw only),
power PC board, longer spacer, small PC board, sRorter
spacer, and disk drive. The power PC board should be
mounted
with the solder side toward the drive.
The power board is now ready to use.
North star MICRO-DISK System
20