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.