MITS 88-DCDD User manual

2450A!amoSE
Albuquerque.NM87t06

PRELIMINARYDOCUMENTATIONRELEASE
THEFOLLOWINGINFORMATIONISA PRELIMINARYRELEASEONLY.
THECOMPLETETHEORYOFOPERATIONWILLBEADDEDTOTHE
ASSEMBLYMANUALATA LATERDATE.THEOPERATORSMANUAL
ANDDOSDOCUMENTATIONWILLBEDEVELOPEDINA SINGLE
MANUALALSO.BOTHOFTHESE,ANDANYUPDATESTOTHIS
ENTIRESYSTEMDOCUMENTATIONWILLBESENTIMMEDIATELY
UPONTHEIRPRINTINGDATE.

OISKOPERATORSMANUAL
INSCRIPTIONOFSYSTEM
A)DISKSPECSHEET
B)OISKSYSTEMBLOCKDIAGRAMDESCRIPTION
1.CONTROLLERBOARD1:
ControllerBoard1 doesallinputfunctionstotheALTAIR
bus(ReadData,SectorData,StatusInformation),aswell
asControlAddressingofallDisktoALTAIRI/O.
2.CONTROLLERBOARD2:
ControllerBoard2 performsalloutputfunctionsfromthe
ALTAIRbus(WriteData,DiskControl,DiskEnableand
DriveSelection).
3.INTERCONNECTCABLE:
An18pairflatcablewithtwo37pinconnectors,a male
ononeend,a femaleontheother.Thiscableconnectsthe
DiskDrivetotheALTAIRDiskControllerand"DaisyChains"
oneDiskDrivetoanotherinmultipleDisksystems.
4.OISKDRIVECABINET:
a)POWERSUPPLY:
TheDiskDriveCabinetcontainsa powersupplyforpowering
theDiskBufferandDiskDrive.
b)THEDISKBUFFER:
TheDiskBufferboardcontainsthenecessarylinedrivers
andreceiversforinterconnectionwithlongcablestothe
DiskDrive.Inaddition,itcontainstheDiskDriveAddress
circuitrythatallowstheControllertoselectoneof16
DiskDrives.
TheDiskBufferboardalsocontainsthelinedriversfor
connectionofmultipleDiskSystems.
c)THEDISKDRIVE:
TheDiskDrive,a PertecF0-400,containsthemechanismand
electronicsthatactuallyreadsar.dwritesdataontheDiskette.

CONNECTIONOFOISKSYSTEM:
A)CONTROLLERBOARDS:
1.ItemsSupplied:
a)CONTROLLERBOARD1 (whitevertstrips)
b)CONTROLLERBOARD2 (withshortcablewiredtoit)
c)CONTROLLERCABLE(with37pinononeend,3 Molexconnec-
torsontheotherend)
d)ConnectorMountingBracketandHardware
2.ConnectionofControllerBoards
a)TakecoveroffALTAIR(poweroff!)
b)FeedMolex(flat)connectorendsofControllercablethrough
holeinbackofALTAIRonconnectorpanel:(37pincon-
nectoroutsidechassis,molexconnectorsinsidechassis).
c)Layboard1 flatinfrontofyouontheALTAIRchassiswith
componentsupandstabconnectortoyourright(asfacing
thefrontoftheALTAIR).
d)Taketheshortwiredcableofboard2 andconnectittothe
20pinconnectoronboard1 (notepolarizationkeyof
connectorandmissingpinonthePCboard).
e)Placeboard2 flat,totheleftofboard1.
f)Connect20pinMolexconnectorontheControllercableto
the20pinconnectoronboard2.NoteKeying.
g)Takethe10pinconnectorontheControllercablewiththe
orangeandyellowwiresconnectedtoitandconnectit
tothe10pinconnectoronboard2.NoteKeying.
h)Taketheremaining10pinconnectorontheControllercable
withwhiteandgraywiresonitandconnectittothe
10pinconnectoronboard1.NoteKeying.
i)Takebothboards,holdtogetherandslideintoslots,with
board1 onright,board2 ontheleft.Besurewires
fromconnectorgooutbetweencardguides,anddonot
catchoncardguides,
j)PushcardsfirmlyintoconnectorinALTAIRmotherboard,
k)Install37pinconnectorinbracketandonbackofALTAIR,
straddling2 connectorholes.Use#4-40x 5/16screws,
lockwashersand#4-40nuts.
B)DISKDRIVECONNECTIONTOALTAIR:
Takethe6 ft.flatcablewith1 maleand1 femaleconnector;
connectmaleendtoDiskControllerconnectoronALTAIR,and
femaleendtoconnectorontheOiskDrivemarked"ToController".

THEALTAIRFLOPPY
D!SKSYSTEM
TheALTA/RDiskofferstheadvantageofnonvolatilememory
plusrelativelyfastaccesstodatuTheAL7A/RDisfcControffer
consistsoftv,oPCboardslover60ICs)thatfitin[heAL7A1R
necttothediskthrougha 37pinconnectormountedonthe
backoftheALTAIRDataistransferredtoandfromthedisk
senallyat250KbitssecThedisk controllerconvertsthesenal
datatoandfromSbitparallelwords(onewordevery32« sec!
TheALTA/RCPUtransfersthedata,wordbywordtoandfrom
memoty.dependingonwnetherthedisk isreadingorwriting
Thedisk controlleralsocontrolsallmechanicalfunctionsofthe
diskaswellaspresentingdisk statustothecomputerAlltiming
tasksSincethe/loppydisketteisdividedinto32sectors,a
hardwareinterruptsystemcanbeenabledtonotifytheCPUat
TheDiskDnveunit,usinga PERTECFD400mountedinan
Optimacase15'?"high—samedepthandwidthascomputer),
includesa poaersuppfyPCboardanda 8u//erAddressLine
temperatureiorcontinuousoperationThedisk dnvecabinet
hastwo37pinconnectorsonthebackpanel,oneistheinput
fromthediskcontroller,theotheristheoutputtoadditionaldisk
dnvesUpto]6dnvesmaybeattachedtoonecontroller
TheMbDCDDconsistsofthedisk controllerandonedisk
dnvewithaninterconnectcableThe MM Diskisonedisk dnvefor
addingstoragecapabilitytothe MM DCDDandincludestheinter
TheAL7AJRDiskFormatallowsstorageofover300.000
bytes.Sincethedisk ishardsectored132sectorsforeachtrack),
wewnte137byiesoneachsector.9 ofwhichareusedinternally
[trackschecksum)leaving128databytespersector.4096per
trackOnefloppydisketteissuppliedwitheachdrive:extraflop-
piesareavailableforpurchaseA so/Maredriverforthefloppy
disk isavailableatnochargeandissuppliedwiththedisk asa
sourcelistingThediskoperatingsystem—whichhasa complete
filestructureandutilitiesforcopying,deletingandsorting
files—costsextraExtendedBASIC.whichusesrandomandse-
quentialtileaccessforthefloppydisk,isalsoavailable.
Speed
AccessTimes
HeadLife
DiskLife
Rate
Power
Diskette
Specifications
360rpm1166.7ms/rev)
Tracktotrack.10ms
Headsettle.20tin
Averagetimetoreador
write.400nis
Worstcase.1 sac
Over10.000hoursofhead
todiskcontact
Over1 millionpasses/track
250Kbits/sec
117VACH0W
Dysan101floppydisk.77tacit*

DISKSYSTEMBLOCKDIAGRAM
10NEXTDISKDRIVE

r

DISKCONTROLLERBLOCKDIAGRAM
SHEETI EXTERNALCONNECTIONSANDAOORESSSELECT
A00HE99 > /
LIHES< LIWCS
CLOCK
^as"—
ooivt
OISK
CONTROLLER
AOORESS
SELECT
CIRCUIT
READ
CIRCUIT
STATUS
CIRCUIT
SECTOR/
tNOEX
CIRCUIT
ouTon[cot
CLOCK
r
I
[
'' e LINES
PIMTOHALTM"
Vt7IMPUT
ALU
POC
BOARD2
WRITE
CIRCUIT
1
CIRCUIT
IWHITEMT4
!o*.*
DISK
DRIVE
SELECT
o*.a
DISK
DRIVE
SELECT o*c^
DISK
DRIVE
SELECT 0*0^
OHKENA9LE
1 OHKENA9LE
STEPIXSTEPIX
FUNCTIONFUNCTION
CONTROL
CIRCUIT
CONTROL
CIRCUIT TBI*EMSE?
OHIVE

DISKCONTROLLERBLOCKDIAGRAM
SHEET2 INTERNALCONNECTIONS
80AR0I

ALTAIRDISKCONTROLLERI/OINFORMATION
A.AddresscodesforI/O
AddressMode
1. 010 Out Select,latchesandenablescontroller
anddiskdrive.
010 In Indicatesstatusofdiskdriveandcontroller.
3. 011 Out Controlsdiskfunction.
4. 011 In Indicatessectorpositionofdisk
5. 012 Out Writedata.
6. 012 In Readdata.
8.Definitions(Inorderaslistedabove)
1.SelectionofDiskDrive"OUT"onCH#010
D0LS8Enables1 of16drives(eachdrivehasa uniquead-
D1dress,selectedby4 jumperwires)andenablescon-
D2troller(ondiskdrivebufferP.C.card).
D3MSB
D4
D5Notused,don'tcare.
D6
D7Clearsdiskcontrolifsetto1 (D0-D6don'tcare).
Disablesdiskcontrol.Oiskcontrolalsocleared
byopeningdoorofdiskdriveorturningdiskdrive
poweroff.
NOTE:a)Ifdiskdrivedoorisopen,driveandcontroller
cannotbeenabled.
b)Ifdiskpowerisoff,driveandcontrollercannot
beenabled.
c)Ifdiskinterconnectcableisnotconnectedbetween
thecontrollerandthedrive,driveandcontroller
cannotbeenabled.

C)MULIIPLLDISKDRIVECONNECTION:
1.WithmultipleDiskDrives,theDisksshouldhavesequential
addresses(i.e.,fora .1drivesystemyoushouldhaveDisks
withaddresses0,1,and2).Theymaybeconnectedinanyor-
der.Thereserial# stickerhastheDiskAddresswrittenon
it.TheDiskAddressisdeterminedbyfourjumperwiresin
theDiskBufferP.C.cardinsidetheDrive,andmaybechanged.
2,ConnecttheDisksbyusingthe6 ft.flatcable.Connectthe
maleconnectortotheconnectormarked"FromNextDisk"onthe
DiskDriveconnectedtotheController.Theotherendofthe
cableconnectstothenextDiskDriveconnectormarked"ToCon-
troller".ThisprocedureisrepeatedforaddedDiskDrive.
III.USINGTHEDISKDRIVE:
A)DISKETTEINFORMATION:
1.AlwayskeepDisketteinenvelopewhennotinuse.
2.KeepDisketteawayfromheat,magneticfields(flourescent
lights,powertransformers,etc.)anddustanddirt.
3.NevertouchrecordingsurfaceofDiskette(oppositelabel
side).
4.AlwaysmarkyourDiskettewithwhatisonthem.Useadhesive
labels,butdon'twriteonthemaftertheyareattached
totheDiskette.
5.TheDisketteusedishardSectored(32Sectorholes,1 index
hole).BlankDiskettesareavailablefromMITSfor$15.00
each.TheDiskettesarenotIBMcompatible.
B)OPERATINGTHEDISKDRIVE:
1.OpendoortoDiskDrivebypullingoutanddown.
2.InsertDisketteintoDrivewithlabelsideup,makingsure
itcatchesonretainingtab.
3.ClosedoortoDiskDrive.
4.IfDiskpowerison,wait10seconds,afterclosingdoor
beforeactivatinganyprogramstoaccesstheDisk.Wait
10secondsafterturningpoweronwithDisketteinDrive
beforeactivatinganyprogramstoaccesstheDisk.Thisis
toallowmotorspeedtostabilize.
5.NEVER:openDiskDrivedoororturnpoweroffwhenDiskEnable
andHeadLoadlightsareon.Therewouldbea goodpossibili-
tythatyouwouldinterruptthesoftwareduringa writefunc-
tion,anddestroydataontheDiskette.
6.Consultsoftwaredocumentationonmethodsusedtoloadbasicor
usesoftware.Forapplicationswheretheuserwishesto
writehisownsoftware.Seelastsection,"ControllerI/O
Information".

2.Status(010- INP)indicatesdiskstatuswhendriveandcontroller
enabled.Alsogivesvalid"INTE"status(05)fromtheALTAIRbus
whencontrollerenabled.
Truecondition= 0,False= 1.
Allfalseifdiskandcontrollerarenotenabled,andallfalseif
nodiskindrive.
D0- ENWO- EnternewWritedata- indicateswritecircuitisready
fornewdatabytetobewritten.Itoccursevery32usand
starts280psaftersectortrue(whenWriteenabled).Itis
resetbyoutputtingtotheWritedatachannel(012).
Dl- MoveHead- Indicatesheadmovementallowedwhentrue(step
IN,stepOUT,).Goesfalsefor10ms,true1 ms,false20
msafterstepcommand.Maystepevery10ms.Goesfalsefor
40msafterheadload.GoesfalseduringWriteand475us
afterWritetoallowcompletionoftrimerase.
D2- HS- HeadStatus- True40msafterheadloadedorstepcommand
Ii*fsteppingwithheadalreadyloaded).Indicateswhenhead
isproperlyloadedforreadingandwriting.Alsoenablessec-
torpositionchannelwhentrue.
03- NotUsed,= 0.
D4- NotUsed,= 0.
D5- INTE- Indicatesinterruptenabled.
D6- TRACK0 - Indicateswhenheadisonoutermosttrack.
D7- NROA- Newreaddataavailable- indicatesthatthereadcir-
cuithas1 byteofdatareadytobetakenfromthereaddata
channel(012).AftertheSYNC*bitisdetected,itoccurs
every32psandisresetbyaninputinstructiononchannel
012.ThebytecontainingtheSYNCbitisthefirstbyte
readfromthedisk.
*See"WriteEnable"

Control(011- Out)- ControlsDiskoperationswhendiskdrive
andcontrollerenabled.A truesignal,logic1,ona dataline
willcontrolthediskasfollows:
00- StepIN- stepsdiskheadinonepositiontohighernumbered
track.
D1- StepOUT- stepsdiskheadoutonepositiontolowernumbered
track.
D2- HeadLoad- loadsheadontodisk- enablessectorposition
status.
D3- HeadUnload- removesheadfromdisksurface,maybeunloaded
immediatelyafter"WriteEnable"(writeandtrimerasecircuits
holdheadloadeduntilthrough).
D4- ^E- InterruptEnable- enablesinterruptstooccurwhenSR0
true(seesectordefinition).
D5- H)- InterruptDisable- disablesinterruptcircuit.Interrupt
circuitalsodisabledbyclearingdiskcontrol.
D6- HCS- HeadCurrentSwitch- mustbetruewhenoutputtinga write
instructionwiththeheadontracks43-76.Thisreduceshead
currentandoptimizesresolutiononinnertracks(automatically
resetatendofwritinga sector).
D7- WriteEnable- initiateswritesequenceasfollows:
1.Diskselectedandenabled,headloaded,enablingsectorstatus.
2.(SectorTrue)detectedfordesiredsector,writecircuit
enabledbysoftware.
3.200usfromWriteEnable,trimeraseautomaticallyturned
on.280usfromstartofsector,"ENWD"goestrue,sync
bytewrittenbysoftware.
4.Firstbytewrittenalwayshasmostsignificant(D7)bitA
"1"(SYNCBit)(mostsifnificantbitwrittenfirst).
5.ENWDgoestrueevery32us.MAX.no.ofdatabytesper
sector137(includingSYNC).
6.Lastor138thbytewrittenmustbea 000.Thiswillbe
writtenfortheremainderofthesector.Ignore"ENWD"
fromthispointtoendofsector.
7. Atendofsector,thewritecircuitautomaticallydisabled,
trimerasedisabled475uslater.

NOTE:a)Writecircuitwillcontinuewritinglastbyteout-
puttedonCH#012totheendofthatsector.
b)Headmaybeunloadedanytimeduringwritecyclrit*no
readorwritefunctioniscxpcctcdaftercurrentwrite
cycle.OnceWriteisenabled,itholdstheheadloaded
fortherequiredtime.(Forwritingandtrimerase).
4.SectorPosition(011- INP)withdiskdriveandcontrollerenabled,
and40msafterheadisloaded,thesectorinformationisasfollows
00- SR0- SectorTrue- Truewhen= 0,andis30pslong.The
writemodeshouldbeginascloseaspossibletothetimethatD0
goestrue.Writedatawillberequested280psafterD0goes
true.Readdatawillbeavailable140psafterSR0goestrue.
SECTOR# 0 1 2 3 31
U1-SR1-0 1 0 1 1
D2-SR2-0 0 1 1 1
D3-SR3-0 0 0 0 1
D4-SR4-0 0 0 0 1
D5-SR5-0 0 0 0 1
b.WriteData(012-OUT)Outputtedonthe"ENWD"statusrequest.
6.ReadData(012-IN)Inputtedonthe"NRDA"statusflag.

()
READ/URITETIMING
DURINGREADORURITEFUNCTION
NLhREADDATAAVAILABLE
(NRDA)) r^
or [_] false
ENTERNEhURtTEDATA
(ENWD)J4-6(Board2)
SECTOR*TRUE-^J—soVs
(BOARD1).
F4- S
WHITEDATAENABLE
(BOARD1)
WRITEEhABLEF.r.
(BOARD2)E2 - 9
EKhD(Board2)^-6
32ps-
]itrue
—Jk-DOWNTIMEDEPENDENTONSOFTWARECYCLETIML
TRIMERASE
(BOARD:)
READCLEAR
(BOARD1)
Jl-9
F! -4
. 2SO tJS
j—- 200tJS-*-
—-j! 40)JS——
If
5.2MS
475 PS-
NRDA(BOARDl)a:-n 2aops

***********ERRATASHEET***********
ALTAIRFLOPPYDISK
DRIVE& CONTROLLER- HARDWAREDOCUMENTATION
March1976
THEFOLLOWINGCHANGESHAVEBEENMADETOTHEABOVE
TITLEDMANUALONTHEPAGESINDICATED.
PAGE32:Noheat-sinkshouldbeusedforeitherXIorX3.Mountboth
oftheseregulatorsdirectlytotheboard.
PAGE95:Usea lengthofwireandconnectthetwopadslabeled+8Vto-
getheralongthebottomedgeoftheboard.
ITISGENERALLYA GOODIDEATOGOTHROUGH
YOURMANUALAMDMARKTHESECHANGESONTHE
PAGESINDICATEDBEFOREBEGINNINGTHEACTUAL
PROCESSOFASSEMBLINGYOURUNIT.
HITS,Inc.
3/16/76

^kccntro^erassemblyprocedure

ASSEMBLYH!MT$
Beforebeginningtheconstructionofyourunit,itisimportantthatyouread
the"M!TSKitsAssemblyHints"bookletincludedwithyourkit.Payparticular
attentiontothesectiononsoldering,becausemostproblemsintheAltair
occurastheresultofpoorsoldering.Itisessentialthatyouusethecor-
recttypeofsolderingiron.A 25-30wattironwitha chiseltip(suchasan
Ungar776witha 7155tip)isrecommendedintheassemblyhintsbooklet.
Someimportantwarningsarealsoincludedinthehintsbooklet.Readthem
carefullybeforeyoubeginworkonyourunit--failuretoheedthesewarnings
couldcauseyoutovoidyourwarranty.
Checkthecontentsofyourkitagainsttheenclosedpartslisttomakesure
youhavealltherequiredcomponents,hardwareandparts.Thecomponentsare
inplasticenvelopes;donotopenthemuntilyouneedthecomponentsforan
assemblystep.Youwillneedthetoolscalledforinthe"KitsAssembly
Hints"booklet.
Asyouconstructyourkit,followtheinstructionsintheordertheyare
presentedintheassemblymanual.Alwayscompleteeachsectionbeforegoing
ontothenext.Twoorganizationalaidsareprovidedthroughoutthemanual
toassistyou:1)Boxed-offpartsidentificationlists,withspacesprovided
tocheckoffthecomponentsastheyareinstalled;2)Reproductionsofthe
silkscreensshowinga)previouslyinstalledcomponents,b)componentsbeing
installedandc)componentsyettobeinstalled,(seebelow)
previously
installed
components
components
yettobe
installed
components
bei ng
installed
-uninE

COMPONENTINSTALLATIONMETHODS
Thissectionofthemanualdescribestheproperpro-
ceduresforinstallingvarioustypesofcomponents
inyourkit.
Readtheseinstructionsoververycarefullyand
referbacktothanwhenevernecessary.Failureto
properlyinstallcomponentsmaycausepermanent
damagetothecomponentortherestoftheunit;
itwilldefinitelyvoidyourwarranty.
Morespecificinstructions,orproceduresofa
lessgeneralnature,willbeincludedwithinthe
assemblytextitself.
Undernocircumstancesshouldyouproceedwithan
assemblystepwithoutfullyunderstandingthepro-
ceduresinvolved.A littlepatienceatthisstage
willsavea greatdealoftimeandpotential"head-
aches"later.
2

PIMt u
o
PINI
rr
PINI
°o
o
PIMI
INTEGRATEDCIRCUITS(IC's)CANCOMEWITHANYONEOF,ORA COMBINATION
OF,SEVERALDIFFERENTMARKINGS.THESEMARKINGSAREVERYIMPORTANTIN
DETERMININGTHECORRECTORIENTATIONFORTHEIC'sWHENTHEYAREPLACED
ONTHEPRINTEDCIRCUITBOARDS.REFERTOTHEABOVEDRAWINGTOLOCATE
PIN1 OFTHEIC's,THENUSETHISINFORMATIONINCONJUNCTIONWITHTHE
INFORMATIONBELOWTOPROPERLYORIENTEACHICFORINSTALLATION.
jWARNINGlINCORRECTLYORIENTEDIC'sMAYCAUSEPERMANENTDAMAGE!
L
E C E
B
THEDRAWINGONTHELEFTINDICATESVARIOUS
METHODSUSEDTOSHOWTHEPOSITIONOFIC's
ONTHEPRINTEDCIRCUITBOARDS.THESEARE
SILK-SCREENEDDIRECTLYONTHEBOARD.THE
ARROWHEADINDICATESTHEPOSITIONFORPIN1
WHENTHEICISINSTALLED.
3