MacFormat 1995 May/macformat-024.iso/Shareware City/Developers/kvik/text/posting1/text0000.txt

Text File | 1995-02-22 | 15.1 KB | 412 lines

THE KVIKKALKUL PROGRAMMING LANGUAGE

Note: this message contains top secret information of the Swedish Navy.
      Possession of this information in Sweden can (and will in most cases)
      lead to Capital Punishment. DO NOT DISTRIBUTE THIS INFORMATION
      TO SWEDEN!!!

INTRODUCTION

When I worked for the Swedish Navy in 1957 as a programmer, my task was to
write programs for the SABINA computer, one of the first transistorised
computers in the world, manufactured by SAAB for use on Swedish submarines.
The computer was located on a test facility in Karlskrona, the Swedish
Navy base. All programming was done in a funky language called 'kvikkalkul',
a language that makes Assembler (or even INTERCAL) look friendly.
The mere existence of SABINA and the programming language 'kvikkalkul' was and
still is top secret. Other top secrets of that age leaked into publicity long
ago, but this one is still preserved. Until now.

Apart from real-time submarine applications such as guided torpedo control, I
did an accounting package in kvikkalkul as well.

THE CHARACTER SET

Kvikkalkul was typed on Baudot encoded teletype machines. Programs were
stored on paper tape. As you might know, Baudot is a five bit code. The
machine can be in two modes, the 'letters' mode and the 'figures' mode.
In 'letters' mode you have the 26 letter symbols, in 'figures' mode you have
the ten digits and some punctuation marks. The codes to switch to the 'letters'
or 'figures' mode, the space, the linefeed and carriage return codes are
available in both modes. Kvikkalkul used symbols from the 'figures' mode
exclusively, therefore it had no letters. If you typed letters in your program
they were interpreted as the corresponding 'figures' mode symbols. Kvikkalkul
had no comments or text literals either; there were no letters in the
language. Period.

The available symbols were: CR/LF, Space, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
period(.), comma(,), quote("), colon(:), dash(-), slash(/) and the left and right
parentheses ( and ).

Each statement was on a separate line.

THE NUMBER SYSTEM

The only data type in kvikkalkul was the signed fixed point fractional number.
The reason for this was that the precision of numbers could be extended without
breaking existing programs. Kvikkalkul was designed for such things as real
time control, so this seemed sensible. The downside was that you had no
integers or whatever other data type. Even arrays were indexed with
fractional numbers.

The minimum precision you could rely on was 15 bits. This is a sign bit and
14 significant fractional bits. The representation was one's complement.
The data word with all bits set (minus zero) denoted overflow. There were
16383 positive numbers, 0 and 16383 negative numbers. The minimum number
was a bit higher than -1 and the maximum number was a bit lower than 1.
You didn't have numbers greater than 1, even not 1 itself.

Every operation that would produce a result outside the range (-1,1)
would return the special overflow value with all bits set.

Numbers were entered as decimal fractions, starting with a comma (the Swedish
representation for decimal point).  e.g. ,125 denotes 1/8.

Kvikkalkul had the following operators

Assignment/pointer
(-  Assignment
-)  Points to
((  Previous
))  Next

Arithmetic
-/- Plus
  --  Minus
)(  Times
-:- Divide
-   Unary Minus

Relational
::  Equal
:/: Not Equal
(   Less
)   Greater
(:  Less or Equal
):  Greater or Equal

Assignment statements consisted of an object, the assignment operator and
an expression. The expression consisted of one operand or two operands
separated by an arithmetic operator. An operand was either a number or
an object with an optional unary minus operator.
Below are two assignment statements

.9 (- ,5
.8 (- .9 )( -,33333333

The first assigns 1/2 to register 9, the second one multiplies register 9 by
1/3 and assigns that to register 8.


THE PROGRAM OBJECTS

The kvikkalkul objects are registers, data pointers, program pointers
and channels. They are denoted by a special symbol followed by a
digit.

There are 10 objects of each type, numbered from 0 to 9. In fact there
were 16 of each, but the other six were secret and for internal use
by the library routines only.

1 REGISTERS

A register can store one number. Registers are denoted by a period(.) followed
by a digit. Registers my be used in assignment statements and as
operands in conditional jump statements.

2 DATA POINTERS

A data pointer points to a data area in memory. Data pointers are denoted
by a slash (/) followed by a digit. Data pointers may be used as registers
in assignment statements and conditional jump statements. The contents of the
memory location the data area points to are used in that case. Before
you can use a data pointer that way, you have to make it point to
a memory location and you have to reserve memory for it.

The statement

333/ 44

declares a storage area for 44 numbers with the label 333.

/0 -) 333

makes data pointer 0 point to the first number in that area.

/0 (- ,127

stores the number ,127 into that location.

/0 ))

makes data pointer 0 point to the next location in that area.

/0 ((

makes it point to the previous location.

Making the pointer point to a random location in the data area, it a bit
tricky. First you have to determine the smallest power of two that is not
less than the size of the data area. For area 333, that is 64. To point to
location n (counting from zero) you have to use a number that's n/64,
e.g. location 16 is the number ,25 The following statement makes the
pointer point to the desired location.

/0 -) 333 ,25

The second operand may also be a register or a data pointer.

3 PROGRAM POINTERS

A program pointer points to a location in the program. Program pointers are
denoted by a colon (:) followed by a digit. Program pointers cannot
be used as ordinary operands in assignment statements and such.

You can declare labels in your program and you can make program pointers
point to them. Then you can jump to those pointers.

The statement

4400:

declares a program label 4400:

:2 -) 4400

makes program pointer 2 point to label 4400.

-) :2

jumps to program pointer 2, in this case it's the label 4400.

Program pointer 0 is the default subroutine return address.
Look at the following program.

.0 (- ,375
:0 -) 6000
:1 -) 100
-) :1
6000:

First a value is assigned to register 0. Then program pointer 0 is made
to point to label 6000. Then program pointer 1 is made to point to label 100.
Next that pointer is jumped to. At label 100 there is the standard subroutine
to print the contents of register 0 to the teletype. After that's
done the subroutine jumps to program pointer 0, and that's label 6000.

There is also a conditional jump, which consists of two operands separated
by a relational operator followed by an ordinary jump statement.

.0 ( ,0 -) :4

means jump to program pointer 4 if register 0 is less than zero.

There are also program pointer storage areas. You declare them as
data storage areas but with /: instead of /

666/: 32

reserves a program pointer storage area for 32 pointers.
You can set a data pointer to this area. If you do this it is illegal
to use that data pointer for data, but now it is legal to assign
program pointers to the data pointer and back.

:3 -) 7777
/4 (- :3

stores the label 7777 (through program pointer 3) into the location the
data pointer 4 points to.

:5 (- /4

sets program pointer 5 to the contents of the memory location the
data pointer points to, in this case label 7777

4 CONSTANTS

Constants are just constants. These are quantities that are hard to
type otherwise. A constant is denoted by a quote(") followed by a digit.
They may be used as ordinary arithmetic operands, but not on the
left hand side of an assignment.

"0 is the minimum number ( -,9999999999999999)
"1 is the smallest distance between two numbers ( 2^-14)
"2 is the special overflow value.
"3 is 1/pi
"4 is ln 2
"5 is 1/32
"6 is 1/sqrt(2)
"7 is sqrt(3)/2
"8 is log 2 (base 10)
"9 is the maximum number (  ,9999999999999999)

5 CHANNELS

Channels are the input/output devices of the computer. Channels are
denoted by surrounding a digit with parentheses. Channels may be used as
operands in arithmetic expressions and conditional jump statements. In
this case the channel is read. They may also be used as the left hand side
of an assignment expression. In this case a value is written to the
channel.

(0) is the teletype channel. The value sent to it/ received from it
is the binary value of the Baudot code divided by 32. If the channel is read
and no character is available, a negative value is returned.

(1) is the paper tape channel. Same remarks as for (0).

(2) is the real time clock. It can only be read. Runs from "0 to "9 in
one hour, then returns to "0 again.

(3) was the random number generator. It could only be read. This was
implemented using germanium noise diodes and it was very unreliable.
If it ran hot, it returned all 1 bits (overflow value) almost all the time.
Its use was highly discouraged.

(4) to (7) are connected to radar, torpedoes or whatever stuff the
computer is supposed to control.


The statement
(0) (- ,03125

sends Baudot code 1 to the teletype.

PROGRAM AND DATA LABELS

Data areas and program pointer storage areas are denoted by numeric
labels in the range 0--32767. The labels above 30000 are reserved for
internal use only and may not be used. A program pointer
storage area and a data area may not have the same label.

Program labels are numbers in the range 0--32767. Numbers below 1000
are reserved for standard subroutines. Numbers above 30000 are
reserved for internal use only and may not be used.

Note that kvikkalkul does not have integers or scaled fractions. But
some of the library routines treat their arguments as if they were
scaled fractions in the range (-256,256) or integers in the
range (16383,16383).

Some of the library routines I still remember are.

11 Multiply integers .0 is .0 times .1
12 Divide integers. .0 is .0 div .1

21 convert fraction to scaled fraction.
22 convert fractional part of scaled fraction to fraction.

31 Multiply scaled fractions.
32 Divide scaled fractions.

48 Wait until character ready on teletype, read to .0
49 same for paper tape.

100 Writes the contents of .0 to the teletype in decimal fraction format.
101 same for paper tape.
150 Reads a decimal fractional number from the teletype to .0
151 same for paper tape.
200 send CRLF to teletype
201 same for paper tape
250 wait until CRLF received from teletype
251 same for paper tape.

300/301 350/351 Number read/write routines for integers in the range
-16383 .. 16383.

302/303 352/353 Same for Scaled fractions (-256,256)

400 square root. (argument and result in .0)
450 Sine (where -1..1 as argument was interpreted as -180..180 degrees)
460 Cosine.
470 Arctan (argument is scaled fraction, result is scaled to (-1,+1)
480 Log (1+x) (base 2)
490 2^x-1

530 Read a line from the teletype into memory pointed to by /0, one
    character per number 0..1 in steps of ,03125
531 Same for paper tape.
540 Write a line to paper tape from memory pointed to by /0, one
    character per number.
541 Same for paper tape.
550/551 560/561 Line read/write routines that packed three characters
    per number, first was 5 most significant bits. These were
    stored more efficiently but a HELL to process, as negatives, positives
    and even overflow was a valid character triplet.

900 Read hour number to .0 Must be called at least twice an hour, because
it relies on the positive/negative transition of (2) to increment the internal
hour number.

666 emergency stop.

888 Dump internal program state to paper tape and stop. Many programs
    needed to do a lot of processing to initialize tables. If text strings
    were needed, they were read from teletype and/or paper tape and
    not written in the program itself. So each nontrivial program had an
    initialization phase in which it read data and computed numbers
    for tables. Then the program called 888. The resulting dump
    could be used by the kvikkalkul compiler to generate a program
    with all tables already initialized.

KVIKKALKUL TODAY

I left the Swedish Navy in 1958 and now I live in a country whose name I
rather not tell. I fear that I will be extradited to Sweden if the
Swedish authorities see this message. What I described was the state of
kvikkalkul in 1958. What I tell in this section is based on rumours,
on tiny pieces of information I got from colleagues and on intelligent
guesswork.

Kvikkalkul is still in use today, at least that was the case in 1991.
There is an Ada to kvikkalkul translator and most new programs are
written in Ada and then translated to kvikkalkul. The kvikkalkul
version was the definitive program that was reviewed, approved,
tested and maintained. There was also a Simula to kvikkalkul translator
in the 70s and some programs were written with it.

Some changes have been made to the language.
The guaranteed precision of numbers was increased over the years and
is now at least 32 bits. Valid label numbers are now in the range
0..4000000000 with some haphazard reserved areas for library routines and
internally used labels. Most library routines that are widely used today
lie in the range 60001-65535. I have no details of them.

The language itself remained remarkably constant. It's still a language
without letters and the smiley notation for operators in still in use,
though for source text the angle brackets may be used instead of parentheses
and + and = are valid substitutes for the -/- and :: operators. Now
new construct have been added and the only data type in the language
is still the fixed point fractional number.  Channel number 3 for
the random generator has been deleted and numbers 8 and 9 were added.

Channel 9 is the OS supervisory channel. By sending messages to it, you can
assign arbitrary files to the channels 0, 1, and 3 through 7. You can
specify the character conversion type of the channels. It is possible
to connect channel 0 to an ASCII terminal and convert all incoming
characters to (more or less) Baudot equivalents and convert all outgoing
Baudot characters back to ASCII. In fact this is the default
for channels 0 and 1. All typical OS services can be accessed through
channel 9.

Channel 8 is the floating point processor. You can send numbers and
opcodes to it and retrieve the computed results. The numbers that you
send to it are 32-bit fractionals that bear no relationship to the FP
numbers as the FP processor sees them. There are library routines
for printing and reading them. The 640000 type standard FP library
calls were made obsolete by channel 8. They still work.

An ex-colleague of mine tried my accounting package from 1958 on
a modern kvikkalkul compiler in 1991. It still works flawlessly, except
that the year cannot be set beyond 1973. He had to retype the program
by hand as there was no suitable 5-bit Baudot paper tape reader for
the system.

-------------------------------------------------------------------------
To find out more about the anon service, send mail to [e-mail].
Due to the double-blind, any mail replies to this message will be anonymized,
and an anonymous id will be allocated automatically. You have been warned.
Please report any problems, inappropriate use etc. to [e-mail].