ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/cpm/walnut-creek-CDROM/CPM/Z280/ZDAM-101.DOC

Text File | 2000-06-30 | 37KB | 697 lines

.op














                 The Need for Direct Access Storage Management

                             A User's Perspective
































                                G. Benson Grey
                             Cedar Mill Z-Node 24

                                August 20, 1987

.paè.pn 1
.he                    DASM - Direct Access Storage Managment                 #

ááááL----!----!----!----!----!----!----!----!----!----!----!----!----!----R
á
                                 INTRODUCTION


ááááThσá purposσá oµ thi≤ perspectivσ i≤ t∩ providσ backgrounΣá informatioε ì
ááááanΣá concept≤ whicΦ ma∙ bσ utilizeΣ iε managinτ disδ datßá file≤á (datß ì
áááásets⌐á oεá microcompute≥á systems«áá Thi≤á topiπá doe≤á no⌠á justif∙á ß ì
áááádissertatioε oε thσ evolutioε oµ microcomputers¼á bu⌠ i⌠ doe≤ justif∙ ß ì
áááádiscussioεá oµ ho≈ technolog∙ ha≤ causeΣ aε evolutioε iεá datßá storagσ ì
ááááanΣá retrieval«á Thi≤á iε turε wil∞ providσ thσ foundation≤ fo≥á ßá ne≈ ì
ááááDirec⌠ Acces≤ Managemen⌠ System.

ááááTherσá ma∙ bσ man∙ morσ factor≤ involveΣ iε thi≤ evolutioε thaε caεá bσ ì
ááááproperl∙ addresseΣ iε thi≤ document«á Therefore¼ onl∙ ß fe≈ factor≤ anΣ ì
ááááthei≥á consequence≤á wil∞ bσ considered«á Amonτ thesσ factor≤ arσá sucΦ ì
ááááthing≤á a≤á improveΣá microcompute≥á capabilities╗áá large≥áá  compute≥ ì
áááámemorie≤á anΣá capacitie≤á fo≥ direc⌠ acces≤ device≤ (flopp∙á anΣá harΣ ì
áááádisks)╗á morσá sophisticateΣ softwarσ anΣ advanceΣá operatinτá systems╗ ì
áááástandardizatioεá oµ communication≤ protocols╗á decreaseΣ cost≤ oµá datß ì
áááácommunications╗ anΣ aε increasσ iε informatioε exchange.

ááááImproveΣ microcompute≥ capabilitie≤ implie≤ ne≈ machine≤ arσ capablσ oµ ì
ááááprocessinτá morσ information¼á morσ efficientl∙ thaε eve≥á before«á Thσ ì
ááááuse≥á oµ thesσ ne≈ device≤ caε expec⌠ t∩ ge⌠ morσ donσ iε thσ samσ timσ ì
ááááa≤ wa≤ previousl∙ possible« Thσ abilit∙ oµ thσ microcompute≥ t∩ proces≤ ì
áááámorσ information¼ ha≤ createΣ demanΣ fo≥ large≥ availablσ memories.

ááááLarge≥á maiε compute≥ memor∙ spacσ ha≤ leΣ t∩ thσ developmen⌠á oµá morσ ì
áááásophisticateΣ software¼ advanceΣ operatinτ system≤ anΣ utilities« Thesσ ì
áááádevelopments¼á iεá turn¼á madσ i⌠ simple≥ t∩ emplo∙ ß compute≥ t∩ solvσ ì
ááááproblems«á User≤ caε bσ les≤ concerneΣ abou⌠ ho≈ t∩ solvσ hardwarσá anΣ ì
áááásoftwarσ problem≤ anΣ morσ concerneΣ abou⌠ whicΦ problem≤ t∩ prograφ oε ì
ááááthσ computer.

ááááContro∞á Program/Monito≥ (CP/M⌐ ha≤ beeε thσ dσ fact∩ operatinτá systeφ ì
áááástandarΣá iεá thσá 8-bi⌠ microcompute≥ domaiε fo≥ thσá pas⌠á 1╡á years¼ ì
áááánewer¼á morσá capablσ operatinτ system≤ arσ emerging«á Thσ ne≈ breeΣ oµ ì
ááááoperatinτáá systeφáá arσá beginninτá t∩á brinτá thσáá advantage≤áá (anΣ ì
áááádisadvantages⌐áá oµá thei≥á mainframσá counterpart≤á t∩á thσáá everyda∙ ì
áááámicrocompute≥ user«á A≤ operatinτ system≤ becomσ morσ sophisticated¼ s∩ ì
áááátoo¼ do thσ users.
.paè
ááááWitΦá thσ standardizatioε oµ communication≤ protocol≤ anΣá availabilit∙ ì
ááááoµ highe≥ speed¼á lowe≥ priceΣ modems¼ digita∞ communication≤ i≤ a⌠ thσ ì
ááááfingertip≤á oµá virtuall∙ ever∙ household«á Communication≤á witΦá othe≥ ì
áááácomputers¼á locateΣ a⌠ grea⌠ distance≤ awa∙ froφ thσ user¼á ha≤á becomσ ì
ááááles≤ fo≥ expensive«á Thi≤ i≤ duσ partl∙ t∩ increaseΣ competitioε iε thσ ì
áááádatßá communication≤á busines≤á whicΦ result≤ iεá lowe≥á lonτá distancσ ì
áááárates«á Thσá othe≥ majo≥ facto≥ i≤ thσ decreasσ iε cos⌠ oµ purchasinτ ß ì
áááádevicσ ablσ t∩ communicatσ ove≥ telephonσ line≤ o≥ satellitσ links« Thσ ì
ááááexchangσá oµá informatioε viß remotσ acces≤ system≤ i≤á expandinτá ver∙ ì
áááárapidly«á Thσ cos⌠ oµ communication≤ i≤ diminishinτ t∩ matcΦ thσá rapiΣ ì
ááááexpansion.

ááááImproveΣá compute≥ capabilitie≤ mean≤ thσ hardwarσ caε d∩ morσá iεá thσ ì
áááásamσ aboun⌠ oµ timσ a≤ wa≤ previousl∙ possible«á Availabilit∙ oµ large≥ ì
áááámemorie≤ fo≥ thσ ne≈ computer≤ ha≤ madσ i⌠ possiblσ t∩ develo≡ advanceΣ ì
ááááoperatinτ system≤ anΣ utilities«á Thesσ facters¼ iε turn¼ demanΣ highe≥ ì
áááácapacitie≤ fo≥ auxiliar∙ storagσ device≤ (disk≤ anΣ tapes)« Movinτ morσ ì
ááááinformatioεá implie≤ wσ mus⌠ movσ thσ informatioε faste≥ t∩á accomodatσ ì
ááááthσ effiencie≤ oµ thσ newe≥ compute≥ systems.

ááááThσábottoφálinσái≤átha⌠ámicrocomputer≤áhardwarσáanΣásoftwarσ and users,ì
ááááhavσá undergonσá aε incredible¼á mind-bogglinτ revolutioε iε ß merσá 1╡ ì
ááááyearsí Thσ relativel∙ unsophisticateΣ hardwarσ anΣ softwarσ oµ thσ pas⌠ ì
áááái≤ gonσ forever« Complex¼ bu⌠ morσ user-friendly¼ hardwarσ anΣ softwarσ ì
áááái≤á thσ curren⌠ trend«á Thσ ver∙ ratσ oµ technologica∞á advancemen⌠á i≤ ì
áááástaggeringíá I⌠ i≤ difficult¼á eveε fo≥ thσ ver∙ adep⌠ compute≥ person¼ ì
áááát∩ kee≡ u≡ witΦ hardwarσ anΣ softwarσ advances.

ááááThσá rea∞ pivota∞ poin⌠ oµ thi≤ wholσ discussioε boil≤ dowε t∩ onσ ver∙ ì
ááááessentia∞ point« Wσ no≈ havσ morσ informatioε t∩ storσ thaε eve≥ beforσ ì
ááááiε ou≥ history« Thσ ratσ oµ datß exchangσ i≤ increasing¼ makinτ greate≥ ì
áááádemands on our storage devices.

ááááDatßá basσ managmen⌠ system≤ allo≈ u≤ t∩ managσ anΣ contro∞á individua∞ ì
áááádatßá elements«á Thσá probleφá no≈ become≤ onσ oµá managinτá datßá filσ ì
áááácollections«á Thi≤á ha≤á leΣá t∩ thσá developmen⌠á oµá filσá managemen⌠ ì
áááásystems«á  Filσá managemen⌠ system≤ allo≈ u≤ t∩ managσ anΣ contro∞ datß ì
ááááfile≤ whicΦ contaiε thσ individua∞ datß elements« Thσ file≤ caε bσ datß ì
ááááo≥ text¼ ß collectioε oµ programs¼ o≥ element≤ oµ thσ operatinτ system.

ááááWhy¼á yo⌡ ma∙ ask¼ i≤ thi≤ ß problem┐ Wh∙ mus⌠ wσ contro∞ al∞ thσ file≤ ì
áááácontaininτ thσ individu∞ elements¼á iµ wσ havσ contro∞ oµ thσá element≤ ì
ááááthemselves┐ Thσ answer¼ again¼ require≤ somσ additional background.
.paè
                                  THE PROBLEM


ááááEarl∙á flopp∙ disk≤ werσ generall∙ 8.00óá single-sided¼á single-densit∙ ì
áááá(SSSD⌐á anΣ coulΣ usuall∙ storσ betweeε 19░ anΣ 25╢ kilo-byte≤ (kB⌐á oµ ì
áááádata«á Theε double-sided¼á double-densit∙ (DSDD⌐ floppie≤ iε botΦ 5.25ó ì
ááááanΣ 8.00ó begaε t∩ increasσ thσ flopp∙ capacit∙ t∩ betweeε 38░ anΣá 60░ ì
áááákB«á Today¼á capacitie≤á oµ u≡ t∩ 1.▓ mega-byte≤ (MB⌐ arσ availablσ fo≥ ì
ááááthesσá tw∩á formats«á Stil∞á smaller¼á 3.50óá flopp∙á disk≤á caεá storσ ì
áááácapacitie≤ u≡ t∩ aε orde≥ oµ magnitudσ greate≥ thaε thei≥ predecessors¼ ì
ááááabou⌠ 1░ MB.

ááááA⌠ thσ samσ time¼ thσ harΣ disk≤ werσ beginninτ t∩ appea≥ oε thσ scene« ì
ááááThesσ earl∙ device≤ coulΣ storσ betweeε ╡ anΣ 1░ M┬ oµ data« T∩ date¼ ß ì
áááá5.25óá 8-platte≥ harΣ disδ i≤ capablσ oµ storinτ u≡ t∩ 76░ M┬ oµá data« ì
ááááS∩á what'≤ al∞ thσ fus≤ witΦ filσ managemen⌠ iµ wσ caε storσá al∞á thi≤ ì
ááááinformatioε oε ß singlσ direc⌠ acces≤ device?

ááááYo⌡á wil∞ recal∞ tha⌠ informatioε exchangσ i≤ increasinτ ver∙á rapidly« ì
ááááRevision≤ t∩ existinτ program≤ abound« Datß filσ content≤ caε changσ oε ì
ááááßá dail∙ basis¼á a≤ i≤ thσ casσ witΦ RA╙ use≥ anΣ messagσá files«á EacΦ ì
ááááday¼á ne≈á filσ upload≤ causσ thσ content≤ oµ ß disδ systeφ t∩á change« ì
ááááSysteφá user≤ constantl∙ revisσ o≥ modif∙ program≤ anΣ datß file≤ whicΦ ì
ááááproducσ ne≈ file≤ differen⌠ froφ thσ file≤ which existed yesterday.

ááááThσ probleφ become≤ onσ oµ ho≈ t∩ managσ anΣ contro∞ aε orderl∙ cop∙ oµ ì
ááááthe higΦ capacit∙ harΣ disδ systems« Thσ proces≤ i≤ calleΣ "backinτ upó ì
ááááthσá harΣ disk«

á ááSincσá mos⌠á microcompute≥ system≤ developeΣ froφ ß flopp∙á disδá baseΣ ì
áááásystem¼á floppie≤á arσ readil∙ availablσ t∩ storσ thσ content≤ oµá harΣ ì
áááádisks« Magnetiπ tapσ cartridge≤ arσ als∩ useΣ a≤ ß backu≡ medium« Thesσ ì
ááááarσ considereΣ "sequentia∞ acccessó devices«á Thi≤ mean≤ i≤ iε orde≥ t∩ ì
áááá"restoreó ß filσ a⌠ thσ enΣ oµ thσ tape¼ wσ havσ t∩ wai⌠ unti∞ thσ tapσ ì
ááááha≤ reacheΣ thσ poin⌠ wherσ ou≥ filσ wa≤ written« Onl∙ theε arσ wσ ablσ ì
áááát∩á restorσ i⌠ t∩ thσ harΣ disk«á Sincσ wσ caε directl∙ positioε t∩ an∙ ì
ááááfilσ oε ß flopp∙ disk¼ i⌠ i≤ classifieΣ a≤ "direc⌠ accessó device.

ááááWha⌠á d∩ wσ d∩ wheε thσ systeφ ha≤ ß systeφ malfunctioε whicΦá destroy≤ ì
áááádatßá file≤á storeΣ oε thσ harΣ disk«á Ho≈ d∩ wσ "restoreó datß t∩á thσ ì
áááádisδ iµ i⌠ ha≤ beeε destroyed┐ WhicΦ file≤ arσ wσ t∩ pu⌠ back┐ Wherσ d∩ ì
ááááthσ file≤ exist┐á Wheε wa≤ thσ las⌠ backu≡ cop∙ made?á Ho≈ ofteε d∩á wσ ì
ááááneeΣ t∩ backu≡ files┐á Wherσ shal∞ wσ "archiveó them┐ Ho≈ man∙ oµ thesσ ì
áááábacku≡ copie≤ d∩ wσ neeΣ t∩ maintain┐ Ho≈ man∙ flopp∙ disk≤ i≤ requireΣ ì
ááááto maintain an adequate archival system?

ááááI⌠ i≤ thesσ question≤ anΣ thei≥ answer≤ whicΦ wil∞ leaΣ u≤ t∩ develo≡ ß ì
ááááne≈á systeφ calleΣ Direc⌠ Acces≤ Monito≥ Systeφ (DAMS)«á Unfortunately¼ ì
ááááwσá canno⌠ dra≈ oε experiencσ froφ thσ microcompute≥ world¼á sincσá thσ ì
ááááprobleφá herσ i≤ onl∙ jus⌠ beginninτ t∩ surface«á Instead¼á wσ neeΣá t∩ ì
áááálooδá a⌠á ho≈ man∙ oµ thσ mainframσ computer≤á managσá thσá mountainou≤ ì
áááávolumσá oµá datß file≤ anΣ ho≈ thσ archiva∞ procedure≤ ma∙á bσá deriveΣ ì
ááááfroφ thesσ principles.
è
                              TOWARDS A SOLUTION


ááááEveεá thougΦá harΣá disδ drive≤ arσ ablσ t∩ storσ morσ datßá thaεá eve≥ ì
áááábefore¼ the∙ arσ stil∞ subjec⌠ t∩ powe≥ outages¼ mechanica∞ failure¼ o≥ ì
ááááothe≥á unexplaineΣ phenomenß whicΦ ultimatel∙ corrup⌠ datß set≤ writteε ì
ááááoε thσ thσ device.

ááááExistinτ datß set≤ agσ anΣ becomσ obsoletσ anΣ ma∙ bσ deleted« The∙ arσ ì
ááááupgradeΣá t∩ replacσ previou≤ versions«á Ne≈ datß set≤ arσ added«á Thi≤ ì
ááááproces≤á continue≤ throughou⌠ thσ lifetimσ oµ datß set≤ storeΣá oεá an∙ ì
áááámagnetiπ media.

ááááLargσá mainframσ computer≤ monito≥ activit∙ oµ on-linσ datß sets¼á and¼ ì
ááááa≤á thσ usagσ (demand⌐ fo≥ thσ datß set≤ diminish¼á thσ datßá set≤á arσ ì
áááácompresseΣá anΣ theε moveΣ t∩ anothe≥ storagσ mediuφ (ßá high-capacity¼ ì
ááááshareΣ storagσ device)«á Thesσ datß sets¼ arσ maintaineΣ oε thi≤ shareΣ ì
áááástoragσá mediuφ fo≥ ß perioΣ oµ timσ anΣ theε migrateΣ t∩ magnetiπ tapσ ì
ááááfo≥ off-line archival« Thσ datß set≤ arσ stil∞ availablσ fo≥ use.

á ááThσá acces≤ timσ requireΣ retrievσ thσ archiveΣ datß se⌠ become≤á quitσ ì
áááálong«á Thσ proces≤ require≤ aε operato≥ t∩ locatσ anΣ moun⌠ thσ correc⌠ ì
áááátape¼á anΣá theε inforφ thσ operatinτ systeφ t∩ restorσ thσ datß se⌠ t∩ ì
ááááaεá appropriatσá device«á Thσ procedurσ i≤ calleΣ restoratioεá oµá datß ì
áááásets«á Thi≤ kinΣ oµ datß se⌠ managemen⌠ i≤ calleΣ ß Hierarchia∞ Storagσ ì
ááááManagemen⌠ System.

ááááMagnetiπá tapσ archiva∞ system≤ arσ expensivσ anΣ arσ stil∞á sequentia∞ ì
ááááiε nature«á The∙ arσ bu⌠ onσ answer« Usinτ flopp∙ disk≤ t∩ archivσ datß ì
ááááset≤ storeΣ oε ß harΣ disδ systeφ appear≤ t∩ bσ ß les≤ expensivσ methoΣ ì
ááááand readily lends itself to almost every microcomputer system today.

ááááA⌠ thi≤ point¼á wσ migh⌠ conside≥ thσ harΣ disδ a≤ aε extensioε oµá thσ ì
áááácomputer'≤á maiε memory«á Eveε thougΦ thσ acces≤ timσ fo≥ ß datß se⌠ i≤ ì
áááádiminished¼ i⌠ i≤ faste≥ thaε accessinτ ß flopp∙ disk« Iε addition¼ thσ ì
áááácapacit∙ oµ thσ harΣ disδ i≤ ofteε severa∞ order≤ oµ magnitudσá greate≥ ì
ááááthaε caε bσ storeΣ oε ß singlσ floppy«á Thi≤ mean≤ tha⌠ thσ mos⌠ activσ ì
áááádatßá sets¼á thosσ iε usσ everyday¼á wil∞ mos⌠ likel∙ bσ storeΣ oεá thσ ì
ááááfastes⌠ device¼ namel∙ thσ harΣ disk.

ááááSince¼á however¼áthσácapacit∙áoµáthσ harΣ disδái≤áfixed¼áwσámust removeì
áááádatß set≤ froφ thσ harΣ disδ t∩ ß flopp∙ disδ iε orde≥ t∩ makσ rooφ fo≥ ì
áááánewer¼áá morσá activσá datßá sets«á Thi≤á proces≤á require≤á tha⌠á somσ ì
áááástatistica∞ informatioε bσ maintaineΣ abou⌠ thσ datß set≤ s∩ tha⌠á onl∙ ì
ááááprope≥ one≤ wil∞ bσ removeΣ froφ thσ on-linσ system.

ááááFo≥ genera∞ users¼á thi≤ proces≤ i≤ no⌠ nearl∙ a≤ complicateΣ a≤ i⌠á i≤ ì
ááááfo≥ operator≤ oµ Remotσ Acces≤ System≤ (RAS)«á Iε thσ forme≥ case¼á thσ ì
áááásysteφá operato≥ generall∙ know≤ whicΦ datß set≤ caε bσ safel∙á removeΣ ì
ááááfroφ thσ on-linσ system« Iε thσ latte≥ case¼ thσ systeφ operato≥ ma∙ o≥ ì
ááááma∙ no⌠ kno≈ whicΦ datß set≤ arσ thσ mos⌠ active«á Somσá files¼á namel∙ ì
ááááutilities¼á arσ ofteε kep⌠ oε thσ systeφ fo≥ ver∙ lonτ period≤ oµ time« ì
ááááOthe≥ datß set≤ changσ s∩ rapidly¼á tha⌠ thσ neeΣ fo≥ aε orderl∙ methoΣ ì
ááááof maintaining them becomes very necessary and very important.è
                               SOME GROUND RULES

ááááBeforσá wσ caε conside≥ implementatioε oµ ß datß managemen⌠ system¼á wσ ì
áááámus⌠ definσ somσ parameter≤ anΣ condition≤ s∩ tha⌠ ß definitioε caεá bσ ì
áááádeveloped« Wσ mus⌠ conside≥ sucΦ thing≤ a≤ flopp∙ disδ capacity¼ volumσ ì
áááálabels¼ seria∞ numbers¼ date¼ timσ anΣ s∩ on« What¼ fo≥ example¼ caε wσ ì
áááád∩á wheε thσ tota∞ capacit∙ oµ ß flopp∙ disδ i≤ les≤ thaε thσ datßá se⌠ ì
áááásize┐á Ho≈ activσ i≤ thσ datß set┐á Wheε wa≤ i⌠ las⌠ accessed┐ Wheε wa≤ ì
áááái⌠ las⌠ archived┐ Ho≈ man∙ archiveΣ copie≤ neeΣ bσ kept┐ Ho≈ ofteε mus⌠ ì
ááááa data set be archived? How long should the archived data set be saved?

ááááLe⌠ us¼ fo≥ ß moment¼ conside≥ ß theoretica∞ system« Le⌠ u≤ als∩ definσ ì
ááááterm≤ anΣ analyzσ thei≥ meaning≤ anΣ consequence≤ a≤ wσ proceed« Fo≥ u≤ ì
áááát∩ d∩ thi≤ properly¼ we'l∞ definσ thσ operatinτ systeφ t∩ bσ CP/═ (o≥ ß ì
ááááCP/═ compatiblσ -- ZRDOS¼ P2DOS¼ etc)« Thσ systeφ ha≤ fou≥ floppie≤ anΣ ì
ááááß 60M┬ harΣ disk« Flopp∙ capacit∙ i≤ eithe≥ 256╦ o≥ 1.2MB¼ althougΦ an∙ ì
ááááothe≥á size≤á arσ equall∙ applicable«á Thi≤ systeφ i≤ accesseΣ b∙á man∙ ì
ááááperson≤ oε ß dail∙ basi≤ (e.g«á RAS)«á Tw∩ flopp∙ drive≤ arσ 8ó anΣ tw∩ ì
ááááarσá 5.25"«á Thσ harΣ disδ i≤ logicall∙ divideΣ int∩ eigh⌠á sub-drives« ì
ááááThσá capacit∙ oµ eacΦ sub-drivσ i≤ fixeΣ a⌠ 7.68MB«á An∙ logica∞á drivσ ì
ááááwil∞ havσ use≥ area≤ 0-1╡ (o≥ 0-3▒ iµ applicable)«

ááááHarΣá disδ mediß i≤ generall∙ considereΣ t∩ bσ non-removable«á Tha⌠ is¼ ì
áááán∩á par⌠ oµ i⌠ caε eve≥ bσ removeΣ froφ thσ system«á Thi≤ implie≤á tha⌠ ì
ááááeacΦ sub-drivσ caε bσ defineΣ a≤ ß fixeΣ booδ o≥ volume« Flopp∙ drives¼ ì
ááááoε thσ othe≥ hand¼ havσ mediß whicΦ i≤ removablσ (disk≤ caε bσ inserteΣ ì
ááááo≥ removeΣ a⌠ will)«á EacΦ flopp∙ disk¼ therefore¼ caε bσ considereΣ t∩ ì
áááábσ ß removablσ booδ o≥ volume«á EacΦ fixeΣ volumσ ma∙ havσ thσ capacit∙ ì
áááát∩ contaiε severa∞ removablσ volumes« WitΦ curren⌠ flopp∙ capacitie≤ i⌠ ì
áááái≤á unlikel∙ tha⌠ ß removablσ volumσ woulΣ contaiε thσ entirσá content≤ ì
ááááoµ ß fixeΣ volume.

ááááOnσá oµ thσ ver∙ firs⌠ thing≤ tha⌠ shoulΣ occu≥ t∩ us¼á i≤ thσ neeΣá t∩ ì
ááááidentif∙ eacΦ fixeΣ o≥ removablσ volumσ tha⌠ caε bσ oε thσ system« Thi≤ ì
ááááidentifie≥ wσ shal∞ cal∞ thσ volumσ labe∞ and/o≥ volumσ seria∞á number« ì
ááááThi≤ means¼á eacΦ flopp∙ disδ will¼ a≤ ß minimum¼ requirσ aε individua∞ ì
áááávolumσ number«á Thσ disδ ma∙ o≥ ma∙ no⌠ havσ aε individua∞ volumσ date« ì
ááááEacΦ volumσ oε thσ systeφ wil∞ havσ ß tablσ oµ content≤ (directory⌐ fo≥ ì
ááááthσ datß set≤ tha⌠ arσ containeΣ oε thσ volume.

ááááNo≈ le⌠ u≤ conside≥ ho≈ ß datß se⌠ (file⌐ i≤ created«á Thσ mos⌠ obviou≤ ì
áááámethoΣ i≤ fo≥ ß use≥ t∩ invokσ aε edito≥ o≥ worΣ processo≥ anΣ creatσ ß ì
ááááne≈ datß set«á Aε existinτ datß se⌠ i≤ editeΣ anΣ ß new¼á modifieΣ datß ì
ááááse⌠á i≤ created«áA remotσ use≥ may upload ß ne≈ datß set«áPerhaps ß ne≈ ì
ááááflopp∙ arrive≤ iε thσ mai∞ witΦ ne≈ datß set≤ oε it«á Les≤ obviou≤á arσ ì
ááááthosσá datß set≤ whicΦ arσ createΣ a≤ ß consequencσ oµ runninτ program≤ ì
ááááo≥ utilities«

ááááEveεá les≤ obviou≤ arσ thosσ datß set≤ whicΦ changσ durinτá thσá norma∞ ì
áááácoursσ oµ systeφ operatioε (messagσ bases¼á upload/downloaΣ logs¼á datß ì
ááááse⌠ descriptions¼ use≥ datß bases¼ disδ directories¼ etc.)« Thi≤ latte≥ ì
áááácasσ i≤ special« ┴ ne≈ datß se⌠ wa≤ no⌠ created¼ bu⌠ rathe≥ aε existinτ ì
ááááonσá wa≤á modifieΣá t∩ contaiε informatioε differen⌠ froφ wha⌠á i⌠á wa≤ ì
áááápreviously.è
                        DATA SET NAMES & VOLUME HEADERS

ááááI⌠ i≤ no⌠ withiε thσ scopσ oµ thi≤ documen⌠ t∩ presen⌠ ß discussioεá oε ì
ááááfilσ naminτ conventions« However¼ ß fe≈ elementar∙ observation≤ wil∞ bσ ì
áááápresented in the interest of clarity and understanding.

áááá┴ datß se⌠ i≤ aε individua∞ file¼á o≥ ß collectioε oµ individua∞ files« ì
ááááAεá examplσ oµ aε individua∞ filσ migh⌠ bσ ZCPR33.Z80«á ┴ collectioε oµ ì
ááááindividua∞ file≤ migh⌠ bσ al∞ thosσ file≤ containeΣ iε aε archivσ o≥ iε ì
ááááß librar∙ (ZCPR33.LB╥ o≥ ZCPR33.AR├ o≥ ZCPR33.ARK)«á Earlie≥ wσ assumeΣ ì
ááááCP/═ compatabilit∙ whicΦ state≤ tha⌠ ß filσ ma∙ havσ aε 8-bytσ namσ anΣ ì
ááááa 3-byte extension.

ááááThσ firs⌠ 8-byte≤ shoulΣ describσ thσ namσ oµ thσ filσ anΣ it≤ revisioε ì
ááááleve∞ (ZCPR30¼ ZCPR33¼ etc.)« Thσ las⌠ 3-byte≤ shoulΣ describσ thσ typσ ì
ááááoµ filσ i⌠ i≤ (ASM¼á DAT¼ DOC¼ HEX¼ LST¼ MAC¼ PRN¼ REL¼ UP─ anΣ s∩ on)« ì
ááááCompresseΣá file≤á generall∙á havσá ß eithe≥ ßá ╤á (Squeezed⌐á o≥á ßá ┌ ì
áááá(Crunched⌐ a≤ thσ middlσ lette≥ oµ thσ filσ type.

ááááSomσá oµ thσ mos⌠ commoε filename≤ containeΣ iε ß datß se⌠á collection≤ ì
ááááarσ -README¼á -READ.ME¼á -README.1ST« Thesσ filename≤ neithe≥ tel∞ wha⌠ ì
áááádatß se⌠ the∙ belonτ to¼á no≥ d∩ the∙ conve∙ an∙ particula≥ informatioε ì
ááááabou⌠á thσá datß set«á Thσ purposσ oµ precedinτ thσ filσ namσ witΦá thσ ì
áááádasΦ o≥ hypheε (-⌐ wa≤ s∩ thσ filenamσ woulΣ sor⌠ t∩ thσ beginninτ oµ ß ì
áááádirector∙ listing«á Presumably¼ thi≤ i≤ s∩ thσ persoε lookinτ a⌠ sucΦ ß ì
áááádirector∙ woulΣ reaΣ tha⌠ filσ first«á Thi≤ i≤ absurd« I⌠ woulΣ bσ mucΦ ì
áááábette≥ t∩ havσ ß filσ extensioε (type⌐ oµ .RM╞ (ReaΣ Mσ First⌐ anΣ havσ ì
ááááthσ 8-bytσ filenamσ represen⌠ thσ samσ collectivσ se⌠ oµ data.

ááááSomσá disδá cataloτ program≤ usσ thσ dasΦ t∩ precedσ thσ volumσá seria∞ ì
áááánumber¼á volumσ name¼á and/o≥ volumσ date/time« Thσ reasoε i≤ thσ same║ ì
áááás∩á thσ cataloτ prograφ wil∞ seσ thσ volumσ identificatioεá first«á Fo≥ ì
ááááthσ purpose≤ oµ ou≥ discussion¼ wσ wil∞ assumσ thσ samσ convention« Fo≥ ì
ááááexample:

áááá          -       .000   <--- Volume Number
áááá          -VOLUME .      <--- Volume Name
áááá          -01JAN87.      <--- Volume Date
áááá          -140045 .      <--- Volume Time

áááá          -VOLUME .000   <--- Volume Name and Number combined
áááá          -01JAN87.000   <--- Volume Date and Number combined
áááá          -140045 .000   <--- Volume Time and Number combined

ááááThσ volumσ numbe≥ ma∙ bσ an∙ numbe≥ betweeε 00░ anΣ 999¼ o≥ betweeε A0░ ì
ááááanΣ Z99« Thi≤ rangσ provide≤ ß maximuφ oµ 360░ volume≤ anΣ wil∞ bσ morσ ì
ááááthaε adequatσ fo≥ most¼ iµ no⌠ al∞ flopp∙ baseΣ disδ systems.

ááááThσá volumσá namσ wil∞ bσ ß dasΦ followeΣ b∙ an∙ combinatioεá oµá valiΣ ì
áááácharacter≤ whicΦ arσ permitteΣ iε ß filσ name«á Thσ volumσ name¼á iµ i⌠ ì
ááááexists, will not be used by the cataloging system at this time.
.paè
ááááThe volume date will be a dash followed by one of the two forms:

áááá          -87JAN01.
ááááor
áááá          -01JAN87.

áááádependinτ upoε thσ implementioε preferred« Purσ numeriπ date≤ shoulΣ bσ ì
ááááavoideΣ t∩ preven⌠ confusioε witΦ thσ volumσ time« Onσ migh⌠ reasonabl∙ ì
ááááargue that the date could be written year, month, day:

áááá          -870101 .

ááááThi≤á methoΣ i≤ acceptablσ s∩ lonτ a≤ thσ rangσ oµ year≤ i≤á restricteΣ ì
áááát∩ betweeε 2┤ anΣ 9╣ sincσ thσ hour≤ caε neve≥ exceeΣ 23« I⌠ present≤ ß ì
ááááproblem¼á however¼á wheneve≥ thσ yea≥ change≤ froφ 9╣ t∩ 00« I⌠ i≤ als∩ ì
áááápossiblσ t∩ selec⌠ ß differen⌠ prefi° fo≥ thσ datσ anΣ time.

ááááThσ volumσ timσ wil∞ bσ ß dasΦ followeΣ b∙ thσ timσ iεá hours¼á minute≤ ì
ááááanΣ seconds« Thσ hour≤ wil∞ bσ kep⌠ iε militar∙ o≥ 24-hou≥ timσ t∩ makσ ì
áááásorting easier. For example:

áááá          -090015 .      <--- 09:00:15 AM
áááá          -210015 .      <--- 09:00:15 PM

ááááTw∩ morσ piece≤ oµ informatioε abou⌠ eacΦ volumσ migh⌠ bσ included║ thσ ì
ááááamoun⌠ oµ availablσ spacσ remaininτ oε thσ volumσ anΣ CR├ o≥á Checksum« ì
ááááAl∞ oµ thi≤ information¼ volumσ name¼ seria∞ number¼ date¼ time¼ space¼ ì
ááááanΣ CR├ wil∞ bσ calleΣ thσ volumσ header« Iµ wσ arσ t∩ accomodatσ thesσ ì
ááááadditional data, a different prefix (modified) may have to be selected.

.paè
                              THE MASTER CATALOG


ááááThσ maste≥ cataloτ contains¼ amonτ othe≥ things¼ thσ namσ oµ ever∙ datß ì
ááááse⌠ containeΣ oε ever∙ volumσ (fixeΣ o≥ removable⌐ tha⌠ caε bσ accesseΣ ì
ááááb∙ thσ system«á I⌠ ma∙ als∩ contaiε sucΦ thing≤ a≤ creatioε datσ and/o≥ ì
áááátime¼á datß se⌠ size¼ checksuφ o≥ CRC¼ numbe≥ oµ accesses¼ datσ oµ las⌠ ì
ááááaccess¼á statu≤ flags¼ backu≡ frequency¼ datσ oµ las⌠ backup¼ retentioε ì
áááácycle¼ locatioε oµ datß set¼ volumσ number(s)¼ etc.¼ anΣ an∙ othe≥ sucΦ ì
ááááinformatioε a≤ ma∙ bσ relative.

ááááIε additioε t∩ thσ maste≥ catalog¼ anothe≥ filσ calleΣ ß Volumσ Cataloτ ì
ááááma∙ bσ required«á Thi≤ cataloτ migh⌠ contaiε thσ volumσ header≤ fo≥ al∞ ì
áááávolumes in the system.

ááááWσ caε no≈ conside≥ buildinτ thσ maste≥ anΣ volumσ catalogs«á Wσá shal∞ ì
ááááconside≥ tw∩ cases║á volume≤ witΦ anΣ withou⌠ headers« Thσ volume≤ witΦ ì
ááááheader≤ i≤ rathe≥ trivial«á Thσ volume≤ withou⌠ header≤ caε bσ resolveΣ ì
ááááiµá thσ cataloginτ systeφ i≤ alloweΣ t∩ generatσ appropriatσ header≤ a≤ ì
ááááthe disks are entered into the system.

ááááWσá caε furthe≥ assumσ thσ harΣ disδ t∩ contaiε datß set≤ whicΦ ma∙á o≥ ì
ááááma∙ no⌠ bσ residen⌠ oε ß removablσ volumσ (floppy⌐ a≤ ß backup«á I⌠ ma∙ ì
ááááor may not have volume headers for each logical sub-drive.

.paè
                              THE PROCESS BEGINS


ááááWσá shal∞ no≈ assumσ wσ havσ enougΦ availablσ spacσ oε thσ harΣ disδ t∩ ì
áááácreatσá anΣ contaiε thσ tw∩ requisitσ catalogs«á Thσ softwarσ ha≤á beeε ì
ááááconfigureΣ for our system. A block diagram of the system follows:



                                  Z80 CPU
                                     |
                                     |
                                     |
áááá Physical Hard Disk Drive (1)    |            Logical Drives E-F
áááá +--------+--------+--------+----+---+--------+--------+-------+
áááá |        |        |        |    |   |        |        |       |
áááá |        |        |        |    |   |        |        |       |
ááááH─ ┼     H─ ╞     H─ ╟     H─ ╚  |  H─ ╔     H─ ╩     H─ ╦á  H─ L
                                     |
                                     |
                                     |
                  Physical Floppies  | Logical Drives A-D
                  +----------+-------+-------+----------+
                  |          |               |          |
                  |          |               |          |
                FD A       FD B             FD C       FD D



ááááAttacheΣá t∩ thσ Z8░ Centra∞ Processinτ Uni⌠ (CPU⌐ i≤ onσ physica∞ harΣ ì
áááádisδá drivσ (6░ M┬ Capacity⌐ anΣ fou≥ physica∞ flopp∙ disδá drive≤á (a⌠ ì
áááá1.▓ M┬ eacΦ ╜ 4.╕ MB)« EacΦ sub-drivσ oµ thσ harΣ disδ i≤ labeleΣ anΣ ß ì
áááálogica∞ uni⌠ numbe≥ ha≤ beeε assigneΣ (H─ ┼ througΦ H─ L¼ inclusive)« ┴ ì
áááásimila≥ se⌠ oµ logica∞ unit≤ anΣ flopp∙ disδ drivσ letter≤ arσ showε iε ì
ááááthe diagram (FD A through FD D, inclusive).

ááááWσ wil∞ assumσ tha⌠ F─ ┴ i≤ thσ systeφ disδ anΣ i≤ neve≥ removed«á F─ ┴ ì
ááááanΣ F─ ┬ arσ 8ó SSSD/DSD─ anΣ F─ ├ anΣ F─ ─ arσ 5.25ó SSSD/DSD─ drives« ì
ááááThσ harΣ disδ i≤ ß 5.25ó 5-platte≥ harΣ disk¼ divideΣ int∩ ╕ equa∞ sizσ ì
áááálogica∞ sub-drives¼ eacΦ witΦ 7.6╕ M┬ oµ storagσ capacity« EacΦ logica∞ ì
ááááunit has user areas 00 - 15 inclusive.

ááááFinally¼á fo≥ thσ sakσ oµ brevity¼á le⌠ u≤ assumσ thσ systeφ ha≤ ß rea∞ ì
áááátimσ clock¼á capablσ oµ providinτ thσ correc⌠ timσ oµ da∙ anΣ date« Thσ ì
ááááformat of the time and date are as follows:

áááá               YY MM DD       <-- Year, Month, Day

áááá               HH MM SS       <-- Hour, Minute, Second

ááááBoth fields are kept in two forms: Ascii and BCD.

.paè
ááááWσ migh⌠ begiε thi≤ proces≤ now¼ b∙ submittinτ eacΦ logica∞ uni⌠ oµ thσ ì
ááááharΣ disδ t∩ thσ prograφ whicΦ wil∞ "createó entrie≤ iε botΦ thσ volumσ ì
ááááanΣá maste≥ catalogs«á Iµ thi≤ prograφ doe≤ no⌠ finΣ thσ datß sets¼á i⌠ ì
ááááwil∞ creatσ them« Iµ thσ datß set≤ arσ found¼ thi≤ prograφ ma∙ checδ t∩ ì
ááááseσá iµ thσ logica∞ uni⌠ (volume⌐ ha≤ beeε previousl∙ processed«á Iµ i⌠ ì
ááááha≤ no⌠ beeε processed¼ i⌠ wil∞ bσ addeΣ t∩ thσ existinτ catalog« Iµ i⌠ ì
ááááha≤ beeε processed¼ thσ use≥ wil∞ bσ prompteΣ t∩ decidσ iµ thi≤ logica∞ ì
ááááuni⌠ shoulΣ replacσ thσ entrie≤ alread∙ existinτ o≥ verif∙ thσ content≤ ì
ááááoµ thσ volumσ agains⌠ thσ maste≥ catalog«á Thσ prograφ wil∞ repor⌠á an∙ ì
áááádescrepancies and prompt the user for appropriate input.ì

ááááThσ prograφ whicΦ create≤ thσ catalog≤ wil∞ reaΣ thσ director∙á entrie≤ ì
ááááanΣ calculatσ thσ amoun⌠ oµ spacσ occupieΣ b∙ al∞ oµ thσ datß sets«á I⌠ ì
ááááwil∞á als∩á calculatσ thσ logica∞ unit'≤ remaininτ space«á ┴ CR├á valuσ ì
ááááwil∞ bσ generateΣ fo≥ eacΦ datß se⌠ wheε i⌠ i≤ processed«á  Thσ namσ oµ ì
ááááthσ datß set¼á it≤ size¼á CRC¼á curren⌠ datσ anΣ time¼ anΣ logica∞ uni⌠ ì
ááááanΣ use≥ areß wil∞ bσ entereΣ int∩ thσ maste≥ catalog« Filσ attributes¼ ì
áááásucΦ a≤ $SYS¼á $R/╧ o≥ $DIR¼ wil∞ se⌠ thσ statu≤ flags« Iµ thσ datß se⌠ ì
áááácome≤ froφ ß "publicó area¼ái⌠ may als∩ bσ markeΣ for download status.

ááááCataloτ entrie≤ sucΦ a≤ retentioε cycle¼á backu≡ frequency¼ etc.¼ coulΣ ì
áááábσ establisheΣ a≤ default≤ iε thσ beginninτ oµ thσ program¼ o≥ thσ use≥ ì
áááácould be prompted. The former is preferable.

ááááEacΦá logica∞ uni⌠ oµ thσ harΣ disδ i≤ processeΣ accordingl∙ t∩ providσ ì
ááááthσá basiπ maste≥ catalog«á Thσ maste≥ cataloτ no≈ contain≤ onl∙á thosσ ì
áááádatß set≤ whicΦ arσ oε thσ harΣ disk«á (Perhap≤ ß cop∙ oµ thi≤ filσ ma∙ ì
áááábe maintained separately.)

ááááThσá cataloτá prograφ migh⌠ no≈ bσ instructeΣ t∩ begiεá cataloginτá thσ ì
ááááphysica∞ flopp∙ disδ units¼á beginninτ witΦ thσ systeφ disk« Thesσ datß ì
ááááset≤ arσ theε addeΣ t∩ thσ maste≥ catalog«á Afte≥ eacΦ flopp∙ disδá ha≤ ì
áááábeeε entereΣ int∩ thσ catalog¼á i⌠ wil∞ contaiε thσ volumσ heade≥ anΣ ß ì
áááácop∙ oµ thσ maste≥ cataloτ whicΦ pertain≤ t∩ it≤ contents« Thi≤ wσ wil∞ ì
áááácal∞ thσ volumσ tablσ oµ content≤ (VTOC)« I⌠ i≤ functionall∙ equivalen⌠ ì
áááát∩ aε expandeΣ director∙ bu⌠ i≤ ß datß se⌠ iε it≤ owε right.

ááááOncσá thσ flopp∙ volumσ ha≤ beeε cataloged¼á thσ operato≥ wil∞ bσ askeΣ ì
áááát∩á placσ anothe≥ disδ (volume⌐ int∩ thσ samσ drivσ (excep⌠ thσá systeφ ì
áááádisk)«á Thσ nex⌠ flopp∙ drivσ iε sequencσ wil∞ theε bσá processed«á Thσ ì
ááááproces≤á wil∞á continuσá unti∞á al∞ oµ thσ physica∞á drive≤á havσá beeε ì
ááááprocessed«á Thσ cataloτ wil∞ no≈ returε t∩ thσ firs⌠ logica∞ uni⌠ afte≥ ì
ááááthσ systeφ disδ (F─ B⌐ anΣ proces≤ thσ volumσ i⌠ contains« Thi≤ proces≤ ì
ááááwil∞á continuσ unti∞ al∞ physica∞ flopp∙ diskette≤ (volumes⌐ havσá beeε ì
ááááentereΣ int∩ thσ maste≥ catalog.
ì
ááááDuplicatσá datß se⌠ name≤ wil∞ no⌠ bσ entereΣ int∩ thσ maste≥á catalog« ì
ááááInstead¼ ß lis⌠ oµ volume≤ whicΦ contaiε thσ samσ datß se⌠ namσ wil∞ bσ ì
áááágenerated«á Thi≤ datß se⌠ i≤ thσ functionall∙ equivalen⌠ t∩ thσ cataloτ ì
áááátha⌠ i≤ currentl∙ generateΣ b∙ MCAT4╡ anΣ MCAT505.

.paè
                            WHAT HATH GOD WROUGHT?


ááááYo⌡á migh⌠ wel∞ asδ a⌠ thi≤ poin⌠ wha⌠ wσ havσá accomplished«á Wσá havσ ì
áááácreateΣ thσ datß set≤ necessar∙ t∩ implemen⌠ ß direc⌠ acces≤ managemen⌠ ì
áááásystem« Wσ no≈ kno≈ whicΦ volume≤ contaiε wha⌠ datß sets« Wσ kno≈ wherσ ì
ááááever∙á datß se⌠ iε ou≥ possessioε resides«á  Wσ kno≈ thσ numbe≥ oµ datß ì
ááááset≤ whicΦ havσ duplicateΣ filσ names« Iε fact¼ wσ eveε kno≈ ever∙ datß ì
ááááse⌠ whicΦ i≤ currentl∙ on-line« Giveε thσ righ⌠ utility¼ wσ arσ ablσ t∩ ì
áááácreatσ ß director∙ oµ ß volumσ no⌠ eveε oε thσ systemí Wh∙ not┐ Wσ kno≈ ì
ááááeverything there is to know about it.

ááááBeforσ wσ caε begiε t∩ explorσ ho≈ sucΦ datß set≤ arσ used¼á wσ mus⌠ bσ ì
ááááablσ t∩ understanΣ ho≈ program≤ anΣ processe≤ caε causσ thesσ datß set≤ ì
áááát∩ bσ changed«á Wσ mus⌠ examinσ wha⌠ wσ mus⌠ bσ donσ wheε ß datß se⌠ i≤ ì
áááácreated¼á modifieΣ o≥ updated¼ o≥ deleted« Jus⌠ ho≈ d∩ wσ kno≈ wheε an∙ ì
ááááof the data sets have changed?

ááááThσ answe≥ i≤ b∙ monitorinτ thσ operatinτ systeφ function≤ whicΦá allo≈ ì
áááádatß set≤ t∩ bσ created¼ erased¼ modified¼ openeΣ anΣ closed« Iε short¼ ì
ááááit means the operating system itself has to be modified!

ááááOh¼á yo⌡ cryí ╔ can'⌠ possibl∙ d∩ that« ╔ don'⌠ havσ thσ sourcσ code« ╔ ì
ááááaφá no⌠á ß programmer«á Wel∞ i⌠ i≤ no⌠ a≤ baΣ a≤ al∞ oµ that«á Wha⌠á i≤ ì
áááátrue¼á however¼á i≤ yo⌡ wil∞ havσ t∩ givσ u≡ somσ memor∙ spacσ anΣá adΣ ì
ááááwha⌠á i≤á calleΣ systeφ overhead«á Systeφ overheaΣ i≤ thσ timσ tha⌠á i≤ ì
áááárequireΣá t∩ monito≥ thσ operatinτ systeφ anΣ takσá appropriatσá actioε ì
ááááwherσ ß datß se⌠ i≤ concerned.

ááááFo≥á thosσá program≤ tha⌠ makσ direc⌠ BDO╙ call≤ t∩á perforφá al∞á disδ ì
áááárelateΣ functions¼á thσ probleφ i≤ relativel∙ simple« ┴ Residen⌠ Systeφ ì
ááááExtensioε (RSX⌐ i≤ created« A≤ thσ namσ implies¼ aε RS╪ live≤ somewherσ ì
ááááiε rea∞ memor∙ (usuall∙ jus⌠ belo≈ thσ CCP)«á I⌠ i≤ resident¼ anΣ i≤ aε ì
ááááextensioεá oµ thσ rea∞ operatinτ system«á Fo≥ thosσ system≤ whicΦá havσ ì
áááábanδ switcheΣ memory¼ thσ RS╪ migh⌠ wel∞ livσ there.

ááááFo≥á thosσ program≤ whicΦ makσ direc⌠ BIO╙ calls¼á thσ probleφ i≤ ß bi⌠ ì
áááámorσ complex¼á bu⌠ essentiall∙ thσ same«á Thσ samσ RS╪ mus⌠ monito≥ thσ ì
ááááBIO╙ call≤ anΣ takσ appropriatσ action« Thσ RS╪ mus⌠ monito≥ botΦ call≤ ì
ááááto the BDOS and the BIOS.

.paè
                               HOW DOES IT WORK


ááááLe⌠á u≤á assumσ yo⌡ wan⌠ t∩ creatσ ß ne≈ filσ witΦ you≥ edito≥ o≥á worΣ ì
ááááprocessinτ program« A≤ fa≥ a≤ you¼ thσ use≥ i≤ concerned¼ yo⌡ simpl∙ g∩ ì
ááááabou⌠ you≥ busines≤ a≤ usual« Wha⌠ happen≤ behinΣ thσ scene≤ i≤ oµ rea∞ ì
ááááinterest.

ááááEssentially¼á thσá edito≥ mus⌠ creatσ ß ne≈ datß set«á Wheε thσá edito≥ ì
áááácall≤ BDO╙ t∩ opeε thσ datß set¼ i⌠ i≤ thσ responsibilit∙ oµ thσ RS╪ t∩ ì
ááááinsurσá tha⌠ ß ne≈ entr∙ i≤ createΣ iε thσ maste≥á catalog«á ┴á simila≥ ì
ááááentr∙á wil∞á bσ createΣ iε thσ volumσ cataloτ iµ necessary«á Thσá entr∙ ì
ááááwil∞ bσ markeΣ temporar∙ unti∞ thσ datß se⌠ i≤ finall∙ closed« Wheε thσ ì
áááádatßá se⌠á i≤ closed¼á al∞ pertinen⌠ datß wil∞ bσ addeΣ t∩á thσá maste≥ ì
áááácataloτ (size¼á CRC¼á date/time¼ retention¼ backup¼ etc.)« Updatinτ thσ ì
áááámaste≥á cataloτ onl∙ wheε thσ datß se⌠ i≤ closeΣ save≤ time«á Iµ ß datß ì
ááááse⌠á i≤á created¼á bu⌠ no⌠ closed¼á thσ fac⌠ wil∞ bσá reflecteΣá b∙á aε ì
ááááappropriatσ statu≤ bi⌠ iε thσ maste≥ catalog«

ááááSuppose¼á tha⌠á we'vσ madσ ß mistakσ iε thi≤ filσ anΣ decidσ wσ wan⌠ t∩ ì
áááádeletσ (erase¼á purge⌐ thσ file«á Wha⌠ d∩ wσ reall∙ mean┐ D∩ deletσ thσ ì
ááááentr∙ froφ thσ maste≥ catalog┐ O≥ d∩ wσ sho≈ i⌠ wa≤ createΣ anΣ deleteΣ ì
ááááon the same day, at different times?

ááááThσ answe≥ shoulΣ bσ obvious«á Wσ kee≡ thσ entr∙ iε thσ maste≥ catalog¼ ì
áááábu⌠ wσ deletσ thσ physica∞ datß se⌠ anΣ it≤ relateΣ entrie≤ iε thσ rea∞ ì
áááádisδ director∙ fo≥ thi≤ logica∞ unit« WitΦ thi≤ method¼ wσ caε discove≥ ì
ááááho≈á datß se⌠ name≤ arσ used¼á anΣ eveε thσ frequenc∙ oµ use«á Program≤ ì
áááátha⌠á coulΣá makσá usσ oµá thi≤á information¼á woulΣá receivσá ultimatσ ì
ááááresponsibilit∙á fo≥ makinτ thσ mos⌠ frequentl∙ useΣ datß set≤ availablσ ì
ááááin the shortest period of time.

ááááThσ algorithφ fo≥ thi≤ methoΣ i≤ ß simplσ leas⌠ recentl∙ useΣ (LRU)« Iε ì
ááááthi≤ method¼á datß set≤ witΦ thσ leas⌠ amoun⌠ oµ activit∙ woulΣ bσ sen⌠ ì
áááát∩ aε archivσ volume«á Oncσ removeΣ froφ thσ mos⌠ activσ datß sets¼ thσ ì
áááádatß se⌠ woulΣ bσ writteε t∩ ß flopp∙ disk¼á anΣ perhaps¼á removeΣ froφ ì
ááááthσ system«á Thσ spacσ i⌠ occupieΣ iε thσ mos⌠ activσ datß set≤ i≤ freσ ì
ááááfor a newer, more active data set.

ááááThi≤ implies¼á incidentally¼á tha⌠ onl∙ thσ mos⌠ activσ flopp∙á volume≤ ì
ááááwil∞ bσ includeΣ iε thσ on-linσ datß sets« I⌠ mus⌠ bσ pointeΣ out¼ tha⌠ ì
ááááwσá mus⌠á no⌠ onl∙ havσ ß wa∙ oµ mountinτ requesteΣ datß sets¼á bu⌠á wσ ì
áááámus⌠ havσ ß simila≥ methoΣ oµ dismountinτ datß set≤ thosσ whicΦ requirσ ì
ááááimmediatσ off-linσ storage«á Generally¼á thesσ wil∞ bσ thσ dail∙ backu≡ ì
áááádatß sets«á The∙ migh⌠ contaiε informatioε regardinτ messagσ base≤á anΣ ì
ááááan∙ ver∙ dynamiπ file« Thσ purposσ i≤ t∩ insurσ tha⌠ wσ caε bacδ u≡ onσ ì
ááááda∙ anΣ restorσ ou≥ mos⌠ volatilσ datß sets«á Iε thi≤ manner¼á wσ woulΣ ì
áááábe more likely to lose only one day's transactions.

ááááDatß set≤ whicΦ tenΣ t∩ gro≈ t∩ infinity¼á ver∙ largσ datß sets¼á coulΣ ì
áááábσ maintaineΣ iε thei≥ entirty«á Extremel∙ large¼á ver∙ slo≈ read/writσ ì
áááástoragσá deviceá woulΣ bσ aε idea∞ medium«á Eveε ver∙ largσá write-oncσ ì
ááááoptical memories would be of considerable value.
.paè
                    ABOUT THE OPERATING SYSTEM AND THE RSX


ááááThσ operatinτ system¼á CP/═ o≥ compatible¼ onl∙ provide≤ thσ mos⌠ basiπ ì
ááááfunction≤ necessar∙ t∩ writσ effectivσ programs« Iµ wσ arσ t∩ havσ morσ ì
ááááfunctions¼á perhap≤ "highe≥ functions"¼á tha⌠ coulΣ bσ performeΣ b∙ thσ ì
ááááRSX¼áá theεáá individua∞áá application≤á coulΣá cal∞á oεá thesσáá newe≥ ì
ááááfunctions«á Iµ wσ follo≈ thi≤ t∩ it≤ logica∞ conclusion¼á onl∙ thσ mos⌠ ì
ááááoften used functions would be available in the fastest computer memory.

ááááRicharΣ Conn'≤ ZCPR│ anΣ brillian⌠ enhancement≤ contributeΣ b∙ talenteΣ ì
ááááartisans¼á i≤ ß profounΣ examplσ oµ thi≤ technique« Iε effect¼ thσ CP/═ ì
áááácommanΣ processo≥ i≤ replaceΣ b∙ ß morσ intelligen⌠ version«á A≤ befit≤ ì
áááásucΦ aε undertaking¼ thσ entirσ substructurσ oµ thσ operatinτ systeφ i≤ ì
áááámoved to accomodate additional subroutine storage and data set buffers.

ááááThσ subroutine≤ providσ additiona∞ "residentó command≤ and/o≥ function≤ ì
áááát∩ contro∞ thσ flo≈ oµ processing«á Hence¼ i⌠ caε bσ seen¼ tha⌠ loadinτ ì
áááádifferen⌠ portion≤ oµ operatinτ system¼á a⌠ differen⌠ times¼ migh⌠ wel∞ ì
áááácontro∞ ho≈ thσ entirσ systeφ functions.

ááááAnothe≥ examplσ i≤ Waynσ Mastersº anΣ Ir÷ Hoff'≤ BYE51░á program«á Thi≤ ì
ááááresiden⌠á extensioε take≤ contro∞ oµ thσ BDO╙ anΣ BIO╙ contro∞ vectors« ì
ááááI⌠ monitor≤ thσ systeφ call≤ anΣ intercept≤ thosσ oµ interest« I⌠ quitσ ì
ááááliterally, patches itself into the system.

ááááBackGrounder¼á Prin⌠ Spooler¼ Datσ Stampe≥ arσ furthe≥ example≤ oµ thi≤ ì
áááámethoΣ oµ functiona∞ systeφ expansion.

.paè
                                 IN CONCLUSION


          If you thought this was then end, then you are dead wrong!

ááááThσ newe≥ processors¼ namel∙ thσ HD6418░ anΣ Z280¼ fo≥ thσ 8-bi⌠ world¼ ì
ááááarσ wel∞ adapteΣ t∩ thi≤ typσ oµ structure«á Whilσ thσ HD6418░ doe≤ no⌠ ì
ááááhavσ al∞ oµ thσ pagσ faul⌠ detectioε oµ thσ Z280¼á i⌠ caε bσ effective« ì
áááá┴ greate≥ numbe≥ oµ "residentó function≤ arσ madσ available¼ anΣ systeφ ì
ááááresponsσ caε bσ quitσ dramatic.

ááááThσ Z280¼á oε thσ othe≥ hand¼ caε handlσ severa∞ "partitionsó anΣ i≤ iε ì
ááááeffec⌠ botΦ multi-tasksinτ anΣ multi-user« WitΦ addressablσ maiε memor∙ ì
ááááexpandablσ t∩ 1╢ MB¼á managinτ datß set≤ wil∞ becomσ imperative« Fo≥ wσ ì
áááámus⌠ realizσ tha⌠ thσ operatinτ systeφ, anΣ it≤ function≤, arσ in fact,ì
ááááa very definite data set. Namely, the data set of available functions.

ááááLargσ maiε memorie≤ allo≈ morσ comple° operatinτ systeφ function≤ t∩ bσ ì
ááááprovideΣá anΣ simplif∙ applicatioε programming«á Iµ man∙á microcompute≥ ì
áááásystem≤ operatσ ß commoε operatinτ system¼ theε applicatioε program≤ oε ì
ááááthesσ system≤ wil∞ becomσ morσ portable«á Onσ oµ thσ fine≥ example≤á i≤ ì
ááááthe UNIX Operating System and its related language 'C'.

ááááThσá Remotσ Acces≤ Systeφ Monito≥ (RASM⌐ anΣ thσ Direc⌠ Storagσá Systeφ ì
ááááMonito≥ (DASM⌐ arσ bu⌠ tw∩ projec⌠ whicΦ requirσ thσ facilitie≤ wσ havσ ì
áááábeeε discussing«á RASM¼ a≤ it≤ namσ implies¼ monitor≤ modeφ anΣ consolσ ì
ááááinput¼ oε ß remotel∙ accessiblσ system« DAS═ monitor≤ anΣ control≤ datß ì
ááááset≤ availablσ fo≥ systeφ use.

ááááWσá 8-bi⌠ CP/═ compatiblσ compute≥ user≤ havσ beeε giveε aε opportunit∙ ì
áááát∩á kee≡ ou≥ wel∞ loveΣ softwarσ anΣ stil∞ enjo∙ thσ benefit≤á tha⌠á i≤ ì
ááááexperienceΣ b∙ simila≥ 16-bi⌠ counterparts« I⌠ i≤ u≡ t∩ thosσ oµ u≤ wh∩ ì
áááásharσ ß concerε t∩ d∩ wha⌠ wσ can«á A≤ wσ work¼ collectively¼ wσ caε bσ ì
ááááprouΣá t∩ kno≈ wσ havσ salvageΣ wha⌠ migh⌠ otherwisσ havσ beeε ßá dyinτ ì
ááááculture.

ááááYou≥ comment≤ shoulΣ bσ iε thσ forφ oµ aε uploadablσ "datß setó t∩á thσ ì
ááááprivatσá uploaΣ area«á Iµ thσ comment≤ caε bσ reasonabl∙ explaineΣ iε ß ì
áááápublic message, then that is preferable. Please direct your comments to


ááááG. Benson Grey, Sysop                   [503] 641-6101 voice
ááááCedar Mill Z-Node  24                   [503] 644-4621 data
áááá12275 NW Cornell Rd, Ste 5              Available on PC Pursuit
ááááPortland,  OR   97229-5611

ááááIµ yo⌡ havσ downloadeΣ thi≤ file¼ pleasσ pas≤ i⌠ alonτ t∩ othe≥ system≤ ì
ááááthat you call regularly. Thanks in advance for your contributions. Ben.