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OOOOThe  Boston  Computer  Society 


February  1984 

Volume  3  Number  2 

Januar-y  Meeti  ng 
Mi gh 1 i gh t m 

Because  of  a  surprise  snowstorm 
the  January  regular  meeting  was 
cancelled  at  the  last  minute. 
The  message  didn't  get  out  to 
everyone,  though,  and  an 
abbreviated  meeting  convened  in 
the  small  science  auditorium 
downstairs  from  our  regular 
meeting  place. 


by  Robert  Douglas 






New  M 


First  Q. 

Full  M 


Last  Q 





























A  Timex  Sinclair  1000  is  being 
used  in  Open  Heart  Surgery  Cases 
at  the  University  Hospital  in 
Boston  to  perform  repetitive 
calculations  of  hemodynamic 
status.  The  calculations  were 
originally  performed  by  hand 
until  the  advent  of  the 
programmable  calculator.  The 
programmable  calculator  reduced 
calculation  time  dramatically, 
but  it  too  had  drawbacks.  For 
example,  inputting  and 
outputting  parameters  from  the 
wrong  register  of  the 
calculator.  With  the  Timex 
Sinclair  computer  this  problem 
is  eliminated  .  The  TSIOOO  can 
print  out  the  input  parameters 
and  the  calculated  parameters 

Led  by  Will  Stackman  and  Jack 
Hodgson  the  meeting  consisted  of 
a  demo  by  Will  of  the  ZX  LR8 
fast  loading  program  from  G 
Russel  1  El ectroni cs. 

The  bulk  of  the  meeting 
consisted  of  a  free-wheeling 
discussion  of  the  Timex  and 
Sinclair  computer  communities. 
There  was  much  concern  about  the 
intentions  and  health  of  The 
Timex  Computer  Corp. 

Although  sparsely  attended  the 
meeting  was  interesting.  For 
future  reference,  meeting 
cancel  1 ati ons  will  be  announced 
on  WHDH  (850  AH)  and  WVBF  (105.7 
FH)  . 

BU  1000 

page  4 

The  Boston  Computer  Society  ;  ■  akr  n 

cv.ii  of  personal  computers  If  you  re  jm.f -rested  m 
•omputers foi  homo,  business  oi  education,  come  to 
The  DCS  for  objt  -cUve  mformatioi  an  i  supper  i  He  • 
3CS  is  the  largest  nonprofit  personal  computer  asso¬ 
ciation  m  the  United  States;  our  goal  is  run  to  pro¬ 
mote  any  particular  brand  of  compute’  but  to  help 
computer  users  and  people  who  just  wan1  to  km  ov 
what  a  computer  could  do  foi  them 

Sign  me  up  for  these  user/interest  groups: 

□  Apple/Boston  (Apple) 

□  Atan  User  Group 

□  Business  User  Group 

□  Consultants  &  Entrepreneurs  Interest  Group 

□  Database  User  Group 

□  Displaywntei  User  Group 

□  Educational  Resource  Exchange 

□  80/Boston  (TRS-80) 

C  Family  Home  User  Group 

□  Logo  User  Group 
G  IBM  User  Group 

G  North  Star  User  Group 
G  Osborne  User  Group 

□  OSI/Boston  (Ohio  Scientific.) 

G  Pascal  User  Group 

G  PET/CBM/VIC  User  Group 

□  Robotics  Interest  Group 
Sinclair /Timex  User  Group 

G  Telecommunications  User  Group 

***  ZX  PRO/FILE  *** 
a  16K+  file  manager  for  the  Timex 

ZX  PRO/FILE  is  a  machine  language  data  base 
that  gives  you  tremendous  versatility: 

*instant  access  to  any  file  stored  in  memory 
★  files  of  any  size  in  the  same  program  run 
★single  or  multiple  word  search  capabilities 
^ordered  file  displays 

^comprehensive  programmable  printer  functions 

A  59  page  manual  comes  with  the  cassette.  In  it 
are  complete  instructions,  examples,  directions 
for  upgrading  to  larger  memories,  modifications, 
program  listings,  and  a  detailed  explanation  of 
how'  the  program  works.  There’s  even  an  intro¬ 
duction  to  machine  coding  for  beginners. 

ZX  PRO/FILE  is  the  best  file  manager  you  can 
get  for  your  Timex.  In  fact,  users  report  that  it 
provides  data  handling  functions  found  only  on 
the  most  sophisticated  systems. 

Price:  just  $16.95 

Let  me  send  you  full  specifications.  Write  to: 

Thomas  B.  Woods 
P.O.  Box  64,  Jefferson,  NH  03583 
Phone:  (603)  586-7734 

OOTTe  Boston 
GO  Computer  Society 

Three  Center  Plaza 
Boston,  MA  02108 

U  S.  Postage 

Permit  1138 
Boston,  MA 

1  O  REM 

There  are  typos  and  there  are 
typos.  Last  month  the  M/L  Group 
highlights  piece  stated 
repeatedly  that  that  group  meets 
on  the  -first  monday  of  the 
month.  That's  not  true.  It  meets 
on  the  first  Wednesday. 

We  try  to  be  very  careful  about 
typos  in  this  publication. 
Especially  those  in  technical 
items  like  data  or  program 
listings.  But  the  way  this 
letter  is  put  together, 
particularly  the  shortage  of 
manpower,  result  in  some  jobs, 
like  proof-reading,  get  less 
attention  than  others.  And  that 
brings  me  to  my  second  item 

We  really  need  some  more  help 
putting  this  newsletter 
together.  Particularly  we  need 
help  with  collecting  and  editing 

the  stories  (an  associate  editor 
)  and  someone  to  help  with  the 
typsetting  and  "cut  and  paste" 
work  of  creating  the  letter  ( 
graphic  artists) .  This 
newsletter  is  an  important 
endeavor  and  we  are  more 
fortunate  than  other  BCS 
newsletters  in  that  we  have  a 
strong  core  of  devoted 
contributors.  Other  larger 
groups  are  impresed  with  the 
supports  we  get.  But  now  we  need 
a  bit  more  support.  If  you  have 
some  abilities  along  these  lines 
call  me. 

Lastly,  the  new  BCS  office  is 
now  open.  It  is  located  at  One 
Center  Plaza,  at  the  other  end 
of  the  plaza  from  the  old 
office.  It  is  a  wonderful 
facility  and  is  going  to  be  a 
real  asset  to  the  Society’s 
growth.  Stop  by  and  visit. 

A  final  note:  Do  you  know  what 
the  difference  is  between  the 
Timex  Computer  Corp.  and  a  Boy 
Scout  Troop?  The  Scouts  have 
adult  supervision. 

O  Boston 



This  newsletter  is  produced  to 
inform  group  members  of  the 
agenda  and  logistics  of  future 
meetings,  as  well  as  to  recap 
and  amplify  the  information 
provided  at  the  meetings.  It 
also  provides  a  forum  for 
members  and  interested  parties 
to  communicate  what  thay  have 
learned  or  developed  relating  to 
Sinclair  and  Timex  computing. 
Meetings  are  open  to  the  public 
(non-member  admission  is  *3); 
however  attendees  are  encouraged 
to  join  the  Boston  Computer 
Society  (BCS)  This  newsletter 
is  free  to  members.  Back  issues 
are  one  dollar  each. 

User  Group  meets  in  the  Large 
Science  Audi ti ori um  (Room  8/2/ 
009)  of  the  University  of 
Massachusetts,  Boston  Harbor 
Campus.  It  is  located  only  3 
miles  from  downtown  Boston  and 
easily  accessible  by  public  and 
private  transportation.  From 
the  north  or  west,  take  the 
Southeast  Expressway  to  Exit  17. 

Turn  left  onto  Columbia  Road. 
Follow  construction  signs  to  get 
to  Morrissey  Boulevard  in  the 
direction  of  UMASS  and  the 
Kennedy  Library.  Bear  right  on 
traffic  island,  get  in  the  right 
two  lanes,  following  UMass/ 
Boston  signs.  Turn  left  at  the 
light  into  Campus.  From  the 
south,  take  Morrissey  Boulevard 
northward  to  the  campus.  On  the 
MBTA,  take  the  Red  Line  CAshmont 
Train)  to  Columbia  Station. 
Transfer  to  the  free  Uni ✓ er s i t y 
shuttl ebus  in  the  T  parking  lot. 


piugs  1,2, and  3  into  your  little 
equation  and  give*  you  back  the 
answer,  in  this  case  putting  it 
in  the  variable  X.  The  values 
you  pass  to  the  funtion  don’t 
have  to  be  actual  numbers  but 
can  be  other  variables! 

X  =  FN  2  (M,  N,  0) 

where  M,N,  and  0  have  been 
established  earlier  in  the 

;be  -following  example  show  a 
more  practical  use  of  DEF  FN.  It 
goes  like  thisi 

DEF  FN  8  ( A, B, C)  -  < A>B> * < A-B> +B 

-<B-C>  * (B>C) 

This  function  is  quite  useful  as 
a  kind  of  bandpass  filter;  that 

FN  S  (1 ef t , x , right ) * 
left,  if  XCleftj 
X,  if  1 ef t<*X<*ri ght 
right,  if  X>right 

The  function  could  be  used,  for 
example,  in  a  game  program  to 
keep  an  object  within  bounds. 

it  a  also  interesting  to  note 

BU  1000  continued 

The  system  consists  of  the 
Si nclair  ZX81  computer  with  16K 
memory,  the  f S2040  printer  and  a 
Sony  Television  which  has  been 
adapted  to  run  off  12  volts  DC 
to  meet  Hospital  Electrical 
Safety  Codes.  The  Timex  supplied 
power  supply  for  the  computer 

inadequate  for  our  application. 

!°  *  new,one  ***  designed  which 
runs  coaler  and  is  more 

reliable.  The  computer  is  left 
on  constantly  to  prevent 
reloading  the  program  daily 
(incidental ly,  it  has  not 
crashed  in  the  six  months  that 
it  ha*  been  in  u*e)  8 

Although  the  Timex  Sinclair 
computer  is  considered  a  toy  by 
some  when  compared  to  other 
larger  and  more  expensive 
computers,  there  are 
applications  for  it  where  large 
computing  power  is  not  required. 

JDur  system,  which  cost  under 
*200,  is  thousands  of  dol 1 ars 
cheaper  than  current  models 
disigned  for  this  application. 

FN  S  (X, Y, Y) “Maximum  of  (X.Y) 
and  * 

FN  S  (X, X, Y) -Minimum  of  (X,Y>. 

[Robert  Douglas  is  a  Clinical 
Engineer  with  the  Anesthesia 
Department  of  the  Uni versi ty 
Hospi tal ,  Boston  Uni versi ty 
Medical  Center! 

The  Sinclair  Timex  User  Group 


Sue  Mahoney 
Di  rector 
c/o  BCS  Office 
or  203-755-2699 

Jack  Hodgson 
Publ isher /Editor 
P.0.  Box  526 
Cambridge,  MA  02238 

John  Kemeny 

User  Group  Correspondent 
284  Great  Road,  Apt.  D5 
Acton,  MA  01720 

Beth  Elliot 
Group  Librarian 
c/o  Sinclair  Research 
50  Staniford  Street 
Boston,  MA  02114 

Allan  Cohen 
Meeting  Coordinator 

Jeff  Parker 
Advertising  Manager 
c/o  P0  Box  526 
Cambridge,  MA  02238 

The  Sinclair  Timex  Newsletter  is 
published  monthly  by  the 
Sinclair  Timex  User  Group  of  the 
Boston  Computer  Society. 
Membership  in  the  BCS  is  »24  per 
year  which  includes  a 
subscription  to  its  magazine 
"The  Computer  Updata"  and 
subscription  to  two  of  its  group 
newsletters  (such  as  this  one). 

Advertising  space  is  available 
in  this  publication  on  a 
limited,  first  come  first  served 
basis.  The  rate  is  *60  per 
quarter  page.  At  this  time  no 
other  ad  sires  are  available. 
c°r  detailed  rate  and  discount 
information  contact  the 
Advertising  Manager  or  the 
Pud 1 i sher . 

The  machine  code  sub-group  met, 
as  usual,  on  the  first  Wednesday 
MONTH)  at  Itek  Optical  Systems 
in  Lexington.  Attendance 
continues  to  grow  in  size  and 
enthusi asm. 

The  meeting  was  opened  with  a 
brief  presentation  by  Jack 
Hodgson  of  the  Zeus  Assembler 
package  for  the  TS2068  Color 
Computer.  The  Zeus  allows  the  m 
/c  programmer  to  enter  their 
code  with  mnemonics  and  symolic 
jump  and  call  addresses.  "This 
is  a  terrific  tool.  It 
simplifies  the  coding  process  by 
a  significant  factor.  I  don’t 
know  how  I  ever  managed  without 
it,"  remarked  Hodgson 
enthusiastically.  The  Zeus 
Assembler  is  from  Soft Sync. 

Dave  Wood  showed  the  group  his 
newly  arrived  Compusa  51/4  inch 
floppy  disk  system  for  the  1000/ 
1500  computers.  "I  really  love 
it."  He  said.  The  drive  loads 
and  saves  programs  and  data  much 
faster  than  the  standard 
cassette  unit.  Although  Dave’s 
drive  was  ordered  in  October  and 
just  arrived  recently.  It  is 
believed  that  Compusa  is  now 
shipping  the  drives  promptly. 

The  group  viewed  a  demo  of  G. 
Russell’s  ZX  LR8  fast  loading 
program.  ZX  LR8  will  load,  from 
cassette,  16K  in  approx.  60 

Group  leader  Bob  Heath  plugged 
the  special  presentations  coming 
up  in  March  (see  elsewhere  in 
this  letter),  and  urged  members 
to  participate  in  the  Dazy 
Project . 

The  Machine  Language  and 
Hardware  Design  Sub-Group  meets 
on  the  first  Wednesday  of  the 
month  at  Itek  Optical  in 
Lexington.  For  details  and 
directions  call  Bob  Heath  days 
at  276-2424. 

ports  available  -for  IN  use  only 
(using  Al). 


It  should  be  noted  that  the  Z80 
interrupt  system  is  pretty  much 
tied  up  by  the  Timex  operating 
system  in  order  to  maintain  the 
TV  display.  It  might  be 
possible  to  utilize  mode  2 
interrupts  by  operating 
exclusively  in  FAST.  In  this 
case,  the  I  register,  normally 
used  for  TV  character 
generation,  could  be  used  to 
vector  the  interrupt  out  of  the 
ROH  and  into  the  user’s 
application  routine.  An 
additional  complication  is 
introduced  by  the  fact  that  the 
A6  address  line  is  tied  to  the 
Z80  INT  line.  To  the  best  of  my 
knowledge,  no  one  has  made  use 
of  interrupts  on  the  Timex 

I  MS  I  DEE  I  NFO 

from  zilog 

On  March  7  the  Machine  Code 
Group  will  host  Mitch  Russo  of 
Nova  Sales  at  their  regular 
meeting  (first  WEDNESDAY).  Mitch 
owns  a  ZX81 .  That  in  itself  may 
not  seem  too  interesting,  BUT  he 
bought  it  so  he’d  have  something 
to  run  his  emulator  on.  You  see 
Mitch  is  the  local 
representati ve  for  Zilog  and  in 
addition  to  promoting  sales  of 
their  products  he  is  an 
enthusiast  of  the  peripherals 
the  Z80  will  support.  Over  the 
years  he’s  built  a  sizable  home¬ 
made  system. 

So,  if  you  want  to  find  out  what 
an  emulator  is  and  hear  lots 
more  about  the  inner  workings  of 
the  Z80  microprocessor  that’s  at 
the  heart  of  all  the  Timex 

Sinclair  computers,  come  join 
with  us  on  the  7th. 

Mitch  has  made  one  request:  he 
asks  that  each  of  us  bring  to 
the  meeting  a  sheet  of  paper 
describing  some  Z80  software  or 
hardware  project  that  we’ve 
either  completed  or  are  working 

For  details  on  last  month’s 
meeting  and  info  about  attending 
see  the  machine  code  group 
highlights  elsewhere  in  this 
newsl etter . 

OIM  THE  TS2068 
by  John  Kemeny 

The  TS2068  has  a  feature  that 
allows  users  to  define  one  line 
functions.  If  you  have  a  math 
formula  that  is  used  many  times 
in  the  program  you  can  program 
it  into  a  ’function’  and  ’plug’ 
any  values  you  choose  into  it. 
For  example  if  you  were  going  to 
multiply  two  numbers  together 
and  then  divide  the  result  by  a 
third  the  formula  might  look 
like  this: 


You  turn  this  into  a  function  by 
using  the  DEF  FN  (beneath  the 
"1"  key),  it  comes  out  looking 
like  this: 

DEF  FN  Z(A,B,C)»(A*B)/C. 

You’ve  now  created  a  function 
called  Z.  When  you  go  to  use 
this  function  you  ’pass’  the 
values  for  A,B,  and  C  by  putting 
them  in  parenthesis  following 
the  function  name.  For  example 
X"  FN  Z  (1,2,3).  The  computer 

and  1 ab*l  *ach  on*  to  avoid 
interchanging  the  values.  The 
physician  can  instantly 
determine  whether  the  readings 
are  valid  and  take  appropriate 

The  program  instructs  the 
physician  to  enter  the  patient's 
weight,  height,  cardiac  output, 
heart  rate,  and  blood  pressure 
measurements  (MPAP,  PCWP,  MAP, 
and  CVP) .  It  then  cal cul ates 
body  surface  area,  stroke 
volume,  stroke  index,  cardiac 
index,  systemic  and  pulmonary 
resistance,  right  and  left  heart 
stroke  work  index ,  and  the  ratio 
of  left  and  right  heart 
resistance.  These  calculated 
parameters  give  the  physician 
valuable  data  on  the  patient's 
condition  and  what  mode  of 
therapy  to  administer.  The  use 
of  the  computer  allows  the 
physician  to  determine  these 
parameter*  rapidly  and  to 
interpret  them  before  they 
become  obsolete.  Shown  below  is 
what  is  displayed  on  the 
television  at  the  start  of  the 
program  to  instruct  the 
physician  on  how  to  enter  each 
of  the  input  parameters.  The 
program  also  performs  a  self 
test  on  itself  to  insure  that  it 
has  loaded  properly,  and  prints 
out  that  it  has  passed. 


E5T  OK 










UHRCTfl C  U  UT  P  UT } 












:  i7t 



Shown  below  are  the  computed 
parameters  along  with  the  input 
which  are  printed  out  on  both 
the  television  and  the  printer . 
The  patient’s  name  can  be  filled 
in  along  with  the  date  and  time. 
Each  printout  is  numbered  in 
consectuti v*  order  at  the  top 
left  hand  corner  next  to  the 
patient' *  name.  The  weight  and 
height  have  to  be  entered  only 
once  for  each  patient  and  are 
stored  in  the  program  until  the 
end  of  the  case. 


WEIGHT  :  200 

HEIGHT  :  70 

C . O .  :  5.2 

H.R.  :  60 

MPAP  :  15 

PGUP  :  10 

MAP  :  80 

CUP  :  5 

STROKE  U GLUME  =  88.3 
STROKE  INDEX  =  39.9 
CARDIAC  INDEX  =  2.4- 

SYS  UAS  RES IS  =  1200 
PUL  UAS  RES IS  =  80 

BU  1000 

page  7 


#£*IMD  OUT  "  m  OIM 
by  Dave  Wood 


There  are  three  types  of  input/ 
output  (I/O)  instructions 
available  on  the  Z80 
mi croprocessor  inside  your 
Timex.  All  generate  a  16-bit 
address,  providing  a  potential 
o-f  65536  I/O  ports. 

1.  Accumulator  I/O  CIN  A,  <n) 

OUT  (n) ,  AD.  The  byte  "n" 
provides  the  lower  8  bits  on  the 
address  bus,  and  the  A  register 
provides  the  high  order  8  bits. 

The  data  is  then  read  into  the  A 
register  from  the  data  bus  (IN) 
or  onto  the  data  bus  -from  the  A 
register  (OUT) .  Note  in  the  use 
o-f  OUT,  that  the  A  register 
plays  a  dual  role.  The  output 
byte  al so  -forms  the  hi gh  address 
byte,  limiting  practical 
applications  to  8— bit  port 

2.  General  register  I/O  CIN  r,  < 

C)  OUT  (C) ,  r 3 .  The  C  regi ster 
provides  the  lower  8  bits  on  the 
address  bus,  and  the  B  register 
provides  the  upper  8  bits.  The 
data  is  read  into  or  out  o-f  the 
specified  regi ster ,  r . 

3.  Block  I/O.  Block  I/O 
instructions  are  available  to 
move  data  between  the  port 
addresses  by  the  BC  regi ster  and 
the  memory  location  pointed  to 
by  the  HL  register. 


The  number  of  I/O  ports  actual 1 y 
avai lable  to  machine  language 
programmers  on  the  Timex  is 
quite  limited.  In  general  the 
lower  three  bits  (AO,  Al,  A2) 
are  reserved  for  control  of  the 
computer.  Furthermore,  the  high 
order  8  bits  may  contain  random 

data,  so  must  be  ignored. 

1 i mi ts  the  user  to  31 
uncontested  I/O  ports. 

Bit  AO  is  used  to  control  the 
keyboard  read  as  well  as 
cassette  input  and  output.  If 
AO  is  low  (logical  0),  then  an 
IN  command  will  activate 
keyboard  scan,  read  the  cassette 
input  line,  and  set  the  cassette 
output  line  low.  An  OUT  command 
with  AO  high  sets  the  cassette 
output  high.  TV  output  is  on 
the  same  si gnal  line  as  the 
cassette,  so  these  IN/OUT 
operations  will  flash  on  the 

Bit  Al  (in  combination  with  AO) 
is  used  to  control  the  SLOW/FAST 
model  it  enabl es/di sabl es 
generation  of  the  non-maskable 
interrupt  (NMI)  every  l/60th 
second .  OUT  with  the  two  lower 
bits  containing  10  activates  the 
NMI  generator  for  the  SLOW  mode. 

OUT  with  the  lower  bits 
containing  01  turns  off  NMI  and 
the  computer  runs  in  the  FAST 
mode.  If  both  bits  are  zero  (00 
) ,  then  the  system  will  crash. 

Bit  A2  is  used  to  control  the 
Timex  Printer .  Bit  A2  low  will 
enable  the  printer. 


For  unrestricted  input/output, 
there  are  31  ports  available. 

Bi ts  A0-A2  must  be  high  to  not 
impact  the  system  operation, 
other  than  toggl ing  the  cassette 
and  TV  signal  lines.  Thus  the 
available  ports  are  (in  hex )  07, 
OF,  17,  IF,  ...  ,  E7 ,  EF,  F7. 
Port  FF  is  used  for  writing  to 
the  tape  cassette.  If  the  Timex 
printer  is  not  being  used,  then 
32  more  ports  are  available, 
making  use  of  the  A2  line. 
Furthermore,  since  OUT  is  the 
most  restrictive  (due  to  the  NMI 
setting)  there  are  32  addi ti onal 

continued  next  page