Z-System Corne� (c)
by Jay Sage
The Computer Journal, Issue 43
Reproduced with permission
of author and publisher
Thi� �tim� �m� �colum� �i� goin� t� b� quit� �short� � I� �respons� �t� �m� �
requests� �� numbe� o� author� hav� submitte� som� ver� interestin� �articles� �
bu� �ther� ha� no� bee� enoug� spac� t� prin� them� � wan� t� mak� sur� �tha� �
thos� �article� �ar� no� delaye� further� On� o� the� i� o� �th� �super� �LS� �
histor� shel� b� Ro� Friefeld� wh� ha� contribute� quit� � numbe� o� excellen� �
�-Syste� �program� (SALIAS� VCOMP� an� BCOMP� t� nam� � few)� Yo� shoul� �no� �
mis� tha� article.
Afte� �workin� �firs� �wit� th� origina� �-Syste� �histor� �shel� �(HS� �b� �
Michae� �Rubenstein� an� the� wit� EAS� b� Pau� Pomerleau� i� occurre� �t� �m� �
tha� �i� �woul� �b� eve� nice� t� hav� � ful�-scree� histor� �shell� � Wha� �� �
envisione� �wa� bringin� th� ful� resource� o� � wordprocesso� t� bea� o� �th� �
comman� �transcript� �s� �tha� �command� coul� �b� �easil� �viewed� �modified� �
reordered� �an� �regrouped� I� th� histor� fil� wer� � standar� �ASCI� �file� �
the� �on� �coul� �massag� �th� fil� wit� � standar� �edito� �o� �eve� �prepar� �
'history� script� i� advanc� fo� specia� purposes.
Afte� �seein� �th� splendi� ful�-scree� wor� Ro� Friefel� ha� don� �i� �hi� �
SALIA� �(Scree� �ALIA� editor)� � aske� hi� i� h� woul� tak� o� �th� �tas� �o� �
writin� �suc� �� histor� shell� H� did� an� h� ha� don� � �splendi� �job� � � �
would� �therefore� �lik� �t� �publicl� �tak� �credi� �fo� �tha� �al�-importan� �
managemen� skil� o� askin� th� righ� perso� t� d� � job!
Softwar� Updat� Service
Whil� Echelo� wa� stil� i� busines� marketin� th� �-System� the� offere� �� �
ver� �nic� �produc� calle� SU� o� Softwar� Updat� Service� � Peopl� �wh� �hav� �
modem� an� � nearb� �-Nod� o� RCP/� syste� generall� d� no� hav� muc� �troubl� �
pickin� �u� �th� lates� release� o� publi�-domai� �-Syste� �an� �genera� �CP/� �
software� � However� fo� thos� wh� d� no� hav� modem� o� fo� who� th� �neares� �
�-Nod� �i� a� expensiv� lon�-distanc� call� obtainin� � ful� se� �o� ��-Syste� �
tool� �o� keepin� u� wit� ne� release� i� muc� mor� difficult� Th� �Echelo� �
SU� �wa� �designe� t� solv� tha� proble� b� makin� th� materia� �availabl� �o� �
diskett� b� mail� I� wa� � dis� subscriptio� service� an� roughl� ever� mont� �
subscriber� woul� ge� � diskett� ful� o� publi�-domai� software.
� �a� happ� t� announc� tha� SU� i� comin� back� thank� t� th� �urgin� �an� �
energ� o� Chri� McEwen� syso� o� th� Socrate� �-Nod� (#32)� i� Plainfield� NJ� �
Chri� an� Bil� Tishey� togethe� wit� Sag� Microsystem� East� wil� b� �offerin� �
a� �eve� mor� extensiv� servic� tha� Echelon's� Bil� Tishey� a� mos� �o� �yo� �
know� �ha� �fo� �som� tim� bee� maintainin� � �complet� �catalo� �o� ��-Syste� �
program� �(ZFILESnn.LST� an� � compendiu� o� HL� file� coverin� al� �o� �them� �
A� �frequen� �intervals� �Bil� release� a� updat� LB� wit� al� �th� �ne� �hel� �
files� � Now� �i� �additio� t� tha� service� Bil� �wil� �b� �puttin� �togethe� ��diskette� wit� th� softwar� a� wel� a� th� documentation.
Thi� �mean� tha� yo� wil� b� abl� t� purchas� diskette� wit� �th� �complet� �
se� �o� �-Syste� program� and/o� subscrib� t� � monthl� updat� service� � Bil� �
an� �Chri� wil� b� handlin� mos� o� th� diskett� production� SM� �wil� �handl� �
th� order� an� bookkeepin� an� wil� produc� diskette� i� th� fe� format� �tha� �
Chri� an� Bil� canno� handl� (8� IB� SSSD� NorthSta� har�-sector� an� �Amstra� �
3").
W� hav� no� ye� worke� ou� al� th� pricin� detail� fo� al� th� options� bu� �
b� �th� tim� yo� ar� readin� thi� column� w� wil� hav� flyer� �availabl� �wit� �
al� �th� information� Jus� dro� m� � lette� o� postcard� o� leav� �� �messag� �
fo� m� i� an� o� th� way� indicate� i� th� sideba� t� thi� column� an� � �wil� �
ge� � flye� t� you� T� giv� yo� som� ide� o� wha� w� ar� talkin� about� � ��-�
mont� SU� subscriptio� t� � U� addres� wil� probabl� b� $4� ($� pe� disk� �an� �
� year'� subscriptio� $7� ($� pe� diskette)� A� yo� ca� see� w� ar� tryin� t� �
kee� th� pric� ver� low� W� reall� wan� al� o� yo� t� b� abl� t� ge� an� �us� �
al� thes� wonderfu� programs.
Full� Customizin� NZCOM
M� �technica� topi� fo� thi� tim� wil� b� abou� designin� full� �customize� �
NZCO� ��-Systems� � hav� alway� bee� satisfie� wit� th� system� tha� �ca� �b� �
produce� s� easil� usin� th� MKZC� (MaK� nZCoM� men�-drive� utility� an� s� �� �
neve� �reall� �delve� �int� �thi� are� ver� much� Abou� � �wee� �o� �s� �ago� �
however� �Dav� Goodma� brough� th� proble� t� me� H� ha� � NorthSta� �Horizo� �
wit� �a� ad�-o� har� disk� an� th� operatin� syste� ha� � RO� stuc� �somewher� �
i� �th� middl� o� th� addres� space� Tha� lef� som� disjoin� block� �o� �fre� �
memory� �an� Dav� reall� wante� t� mak� us� o� al� th� space� � tol� �hi� �m� �
standar� answe� t� tha� problem.
I� sectio� � (especiall� subsectio� 5.2.3� o� th� NZCO� manual� � poin� ou� �
tha� th� NZCO� syste� i� define� b� � descripto� fil� an� tha� thi� fil� (wit� �
typ� �ZCM� �i� � pur� ASCI� fil� tha� ca� b� edite� wit� one'� �favorit� �tex� �
editor� Th� manua� recommend� tha� everyon� mak� certai� change� s� tha� �th� �
descripto� wil� properl� reflec� th� user'� hardwar� environment� suc� a� �th� �
dis� �drive� �availabl� an� th� characteristic� o� th� �system'� �printe� �an� �
terminal.
� �di� �no� �actuall� �com� ou� an� sa� i� �explicitly� �bu� �ther� �i� �a� �
implicatio� tha� othe� value� i� th� ZC� fil� ca� als� b� changed� Th� �trut� �
is� � believe� tha� � avoide� thi� subjec� i� par� becaus� � wa� no� �entirel� �
sur� whic� value� coul� an� whic� value� coul� no� b� changed� M� �suggestio� �
t� Dav� Goodma� wa� tha� h� experimen� wit� designin� � custo� memor� ma� �fo� �
hi� �system� edi� th� value� int� th� ZC� file� an� se� wha� happene� whe� �h� �
trie� t� loa� it.
Dave'� �repor� �bac� �t� �me� no� confirme� b� m� �ow� �experiment� �o� �m� �
Televide� �803H� �indicate� �tha� �AL� �value� �ca� �b� �changed� � Th� ��onl� �
requiremen� �i� �tha� �th� �value� �provid� �� �memor� �ma� �wit� �n� �module� �
overlapping� � Whe� �yo� �us� MKZC� t� desig� th� system� i� �take� �ove� �th� ��responsibilit� �fo� �generatin� �� �vali� memor� map� i� �yo� �d� �th� �desig� �
yourself� yo� bette� b� careful.
� Helpfu� Utility
Thi� �suggest� � ver� nic� utilit� progra� tha� som� thoughtfu� sou� �coul� �
contribut� �t� �th� community� Thi� utilit� (let'� cal� i� ZMAP� migh� �d� �� �
numbe� o� helpfu� things� First� i� coul� display� perhap� i� som� �graphica� �
o� sem�-graphica� way� th� memor� ma� o� � �-System� th� on� actuall� �runnin� �
o� �on� specifie� i� th� for� o� � ZC� o� EN� fil� (an� mayb� eve� th� �Z3PLU� �
descripto� �fil� �o� typ� Z3P)� Presen� utilities� suc� a� SHO� �(ZSHOW� �an� �
Z3LOC� lis� th� modul� addresse� i� � fixe� order� no� i� orde� o� �increasin� �
memor� �address� Thu� the� ar� no� ver� helpfu� i� determinin� i� �ther� �ar� �
gap� �o� �overlap� i� th� map� Ideally� ZMA� woul� fla� an� suc� �defect� �o� �
potentia� defect� i� th� ma� s� tha� the� coul� b� correcte� befor� the� caus� �
harm.
Th� fina� ite� o� m� wishlis� �� an� thi� migh� bette� b� implemente� i� �� �
second� �independen� progra� (ZDESIG� perhaps� �� woul� b� � genera� ��-Syste� �
designer� alon� th� line� o� MKZC� bu� withou� it� restrictions� On� woul� b� �
abl� t� specif� th� orde� o� al� th� module� i� memor� an� thei� sizes� Give� �
th� �highes� memor� addres� available� th� progra� woul� the� figur� �ou� �an� �
displa� �th� memor� map� On� shoul� b� abl� easil� t� alte� th� orde� o� �th� �
modules� an� on� shoul� b� abl� t� overrid� specifi� addresse� t� creat� �gap� �
i� �necessar� (bu� no� t� forc� overlaps)� Onc� th� desire� syste� �ha� �bee� �
designed� �th� �progra� �shoul� writ� ou� � ZC� o� EN� fil� fo� �it� � Suc� �� �
progra� i� � goo� candidat� fo� implementatio� wit� � hig� leve� languag� suc� �
a� �BD� �� �o� �Turb� �Pascal� An� i� sur� woul� �hav� �helpe� �m� �wit� �th� �
experiment� �tha� �� �a� �abou� t� �describ� �(severa� �mistake� �resulte� �i� �
crashes).
M� Experiments
Fig� �� �show� � printou� o� th� standar� NZCOM.ZC� fil� �o� �m� �Televide� �
803H� I� ha� alread� bee� customize� i� severa� way� usin� MKZCM� First� �i� �
allocate� � �-recor� VBIOS� � us� � versio� tha� fixe� th� 803'� fau� pa� �o� �
clobberin� th� inde� register� durin� BIO� call� an� implement� � chec� o� th� �
�-Syste� �driv� vecto� fo� BIO� dis�-selec� call� a� describe� i� �� �previou� �
column� I� als� ha� roo� fo� � 2�-recor� RCP� whic� allow� m� t� us� � �ful�-�
feature� �RC� �wit� Carso� Wilso� an� Ro� Friefeld'� residen� �histor� �shell� �
CLE� (se� RCPZRL11.LB� o� �-Nodes).
-----------------------------------------------------------------------------
E606 CBIOS 0080 ENVTYP E3F4 EXPATH 0005 EXPATHS D300 RCP
0014 RCPS 0000 IOP 0000 IOPS DD00 FCP 0005 FCPS
DF80 Z3NDIR 0023 Z3NDIRS E400 Z3CL 00CB Z3CLS E280 Z3ENV
0002 Z3ENVS E200 SHSTK 0004 SHSTKS 0020 SHSIZE E380 Z3MSG
E3D0 EXTFCB E4D0 EXTSTK 0000 QUIET E3FF Z3WHL 0004 SPEED
0010 MAXDRV 001F MAXUSR 0001 DUOK 0000 CRT 0000 PRT
0050 COLS 0018 ROWS 0016 LINS FFFF DRVEC 0000 SPAR1
0050 PCOL 0042 PROW 003A PLIN 0001 FORM 0000 SPAR2
�0000 SPAR3 0000 SPAR4 0000 SPAR5 BB00 CCP 0010 CCPS
C300 DOS 001C DOSS D100 BIO 0000 PUBDRV 0000 PUBUSR
Figur� �1� � Th� ZC� descripto� fil� fo� th� norma� NZCO� syste� � us� �o� �m� �
Televide� 803� computer.
����������������������������������������������������������������������������-
� �decide� �t� b� cautious� especiall� afte� on� o� m� ne� �syste� �design� �
cause� th� syste� t� hang� an� � mad� � serie� o� systems� eac� differen� fro� �
th� �previou� on� i� � relativel� smal� way� � a� no� goin� t� sho� �yo� �al� �
th� �step� �alon� th� wa� bu� wil� g� righ� t� th� �mos� �radicall� �differen� �
version� Se� Fig� 2� I� yo� loo� carefully� � thin� yo� wil� fin� tha� �onl� �
th� �comman� �lin� buffe� (Z3CL� i� stil� i� th� sam� plac� a� i� wa� �i� �th� �
origina� syste� (bu� i� i� bigge� now).
-----------------------------------------------------------------------------
E606 CBIOS 0080 ENVTYP E3F4 EXPATH 0005 EXPATHS D700 RCP
0014 RCPS 0000 IOP 0000 IOPS D480 FCP 0005 FCPS
D200 Z3NDIR 0023 Z3NDIRS E400 Z3CL 00FB Z3CLS E180 Z3ENV
0002 Z3ENVS E100 SHSTK 0004 SHSTKS 0020 SHSIZE E280 Z3MSG
E2D0 EXTFCB E300 EXTSTK 0000 QUIET E2FF Z3WHL 0004 SPEED
0010 MAXDRV 001F MAXUSR 0001 DUOK 0000 CRT 0000 PRT
0050 COLS 0018 ROWS 0016 LINS 000F DRVEC 0000 SPAR1
0050 PCOL 0042 PROW 003A PLIN 0001 FORM 0000 SPAR2
0000 SPAR3 0000 SPAR4 0000 SPAR5 BA00 CCP 0010 CCPS
C200 DOS 001C DOSS D000 BIO 0000 PUBDRV 0000 PUBUSR
Figur� 2� � radicall� reconfigure� NZCO� syste� produce� b� manuall� �editin� �
th� ZC� file.
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Perhap� yo� ar� wonderin� wh� � didn'� mak� th� mos� dramati� demonstratio� �
possibl� b� changin� absolutel� ever� addres� (an� perhap� size� too)� � Well� �
ther� �wa� �a� extr� constrain� tha� � wa� explorin� wit� thi� system� � � �a� �
runnin� �ZDDOS� an� � hav� specifie� tha� th� cloc� drive� b� loade� int� �th� �
s�-calle� �use� �buffer� � hav� eve� applie� th� NZCO� �patc� �(NZCOMPAT.HEX� �
tha� come� wit� th� ZSDOS/ZDDO� packag� s� tha� whe� ne� syste� configuration� �
ar� �loaded� �th� cloc� drive� wil� b� reconnecte� t� �th� �DO� �automaticall� �
withou� th� nee� fo� runnin� LDTI� again.
I� yo� kno� � lo� abou� �-System� yo� wil� kno� tha� ther� i� n� suc� thin� �
a� �� use� buffer� Th� use� buffe� i� � specia� creatur� o� NZCOM� i� i� �no� �
define� �i� th� �-Syste� environmen� descripte� (o� �� loo� closel� �� i� �th� �
ZC� file)� How� then� doe� on� determin� wher� thi� specia� ga� i� th� memor� �
ma� o� a� NZCO� syste� i� located� Tha� i� exactl� wha� � wondere� myself� � �
coul� �hav� �calle� ZDO� author� Ca� Cotril� o� Ha� Bowe� an� aske� �the� �ho� �
the� �infe� it� location� bu� � decide� t� experimen� instead� Wha� �� �foun� �
afte� �variou� trial� an� error� wa� tha� th� NZCO� patc� seeme� t� �b� �happ� �
an� �abl� �t� fin� th� LDTI� cloc� modul� s� lon� a� th� comman� �lin� �buffe� �
staye� �i� th� sam� place� Apparently� th� assumptio� i� mad� tha� �th� �use� ��buffe� �i� th� memor� fro� 100� abov� th� star� o� th� comman� lin� buffe� �u� �
t� th� rea� CBIO� (E40� t� E5F� i� m� case).
� �di� �no� perfor� exhaustiv� test� o� thi� hypothesis� Le� u� �jus� �sa� �
tha� �i� i� no� terribl� pruden� t� tr� t� mak� us� o� � 'use� buffer� wit� �� �
full� �customize� system� I� woul� b� wise� t� desig� th� syste� wit� �� �ga� �
belo� th� CBIO� fo� th� cloc� drive� an� t� creat� � versio� o� LDTI� wit� �a� �
explici� �loa� �address� Th� NZCOMPA� patc� shoul� b� omitte� fro� �NZCO� �i� �
suc� custo� system� ar� goin� t� b� used.
A Few Bugs
Ther� �wer� �� �fe� bug� i� NZCO� tha� surface� durin� �thi� �testin� �tha� �
sugges� tha� NZCOM.CO� wa� no� quit� designe� t� wor� rigorousl� an� t� handl� �
th� �mos� �genera� �syste� loadin� situations� Sometime� �� �foun� �tha� �ND� �
module� �becam� empty� an� th� comman� searc� pat� wa� rarel� �preserve� �wit� �
thes� systems� Cod�-containin� modules� suc� a� th� FCP� RCP� DOS� an� s� on� �
canno� �b� �move� �fro� on� addres� t� another� � I� �thei� �startin� �addres� �
changes� �th� �cod� mus� b� reloade� fres� fro� th� ZR� file� � O� �th� �othe� �
hand� �module� tha� contai� data� suc� a� th� NDR� shel� stack� path� �messag� �
buffer� �an� �s� on� ca� an� shoul� b� move� t� an� ne� address� �s� �lon� �a� �
ther� i� roo� fo� th� ol� content� i� th� ne� home� NZCO� sometime� faile� t� �
d� this� Mayb� no� tha� � hav� uncovere� thes� smal� problems� � ca� pas� th� �
informatio� �o� �t� �Jo� Wright� an� h� ca� fi� u� th� cod� �t� �handl� �thes� �
situations.
[Thi� articl� wa� originall� publishe� i� issu� 4� o� Th� Compute� Journal,
P.O� Bo� 12� Sout� Plainfield� N� 0708�-001� an� i� reproduce� wit� the
permissio� o� th� autho� an� th� publisher� Furthe� reproductio� fo� no�-
commercia� purpose� i� authorized� Thi� copyrigh� notic� mus� b� retained.
(c� Copyrigh� 1990� 199� Socrate� Pres� an� respectiv� authors]