ZX Cesil 2(ID:7792/)

Country: uk
- languages for uk
- uk/1983
Began: 1983

?Improved version of Cesil by John Miller

ZX Cesil 2

Extension of

References:

Miller, John "ZX-CESIL 2" ZX Computing Apr/May&Jun/Jul.1983 view details Abstract: John Miller has taken a quick break from his A-levels to
prepare us a splendid implementation of the educational
computer language for your ZX Spectrum

Those people studying for 'O' level or 'CSE' Computer
Studies at school, more than likely have to learn the
language CESIL (Computer Education in Schools Interactive
Language) which supports 14 program statements as standard
and a handful of commands. The language I chose to implement
CESIL in was ZX Spectrum BASIC - with 48K RAM. (The use of a
ZX Printer is optional.)

Type in the program (carefully!) and then enter the command:

RUN 1

Two pages of introduction will be displayed, then you will
see the prompt:

Which mode (1 or 2)?

In reply, enter 1 or 2.

Mode 1 means output to screen only and mode 2 means output
to both screen and printer. The Spectrum's screen BORDER
state depends upon the current mode:

Green  for Mode 1
Yellow for Mode 2

When the message 'C?' is output, you are required to enter a
CESIL command:

COMMAND NOTES
beg - Execute the CESIL program.
cha - Change a CESIL line.
del - Delete a CESIL line.
lis - List the CESIL program.
new - Re-initiate program - same as stopping the program and entering RUN 1.
ter - Stop the interpreter - terminate.
*   - Start CESIL entry.

When using 'cha' or 'del', the first parameter is the line
to be edited (del followed by Enter followed by 5 followed
by Enter, will delete the fifth line).

When '?' is output, you are required to enter a CESIL line.
Labelled lines are l1 to l99 and store locations are
designated a1 to a99 (positive constants do not require
'+'). Please note that 'l' means 'label'.

Types of argument

a - The argument required is:
    (i) Space, any whole number between -32768 and +32768.
or (ii) Space, a ; any integer between 1 and 99.
eg. (i) loa -2
   (ii) add a5

b - The argument required is:
    Space, 'l' , any integer 1 to 99.
eg. jiz l10

c - The argument required is:
    Space, quote, any alpha-numeric text of length 1 to 22, close quote.
eg. pri "Hello there!"

d - The argument required is:
    Space, a, any number 1 to 99 (integer).
eg. sto a86

e - The argument required is:
    Any alpha numeric text of length 1 to 23.
eg. ; This is a comment

n - No argument required.

All instructions are standard, except 'kin', which is the
same as BASIC's INPUT number. The instruction 'in' is the
same as BASIC's READ. All arithmetic is calculated solely
using the accumulator.

In order to exit from CESIL 2 entry, enter:

%

As a line, you will then be asked to enter the data string
in the form:

n1,n2,n3,...nx, *
n1=item 1
n2=item2...
nx=last item
eg. 1,2,3,5,7,9, *
(Note the comma before the *)

For no data, just enter an asterisk. (Also, only the first
20 items will be accepted.)

To change the data for another RUN of the same program:

     PROMPT     ENTER
     C?     *
     ?     %
     Data?   data string

Also, if after entering and executing a CESIL program, entry
mode is again initiated and the lines will be added to the
end of the previous lines. The number of program lines
available is 100 (that's my limit - not the Spectrum's).

To change the maximum number of lines, make the following
changes to the BASIC program (!! = the number instead of 100
- maximum value 255).

  20 ...: DIM p$ (!!,25): ...
1380 FOR x=1 TO !!
2030 FOR z=VAL i$ + 1 TO !!
3710 IF lastln<(!!+1) THEN GO TO 3750
4180 FOR c=1 TO !!

During CESIL2 execution or CESIL2 listing (lis), command
mode may be achieved by pressing the space key - as long as
it is unshifted!

Labelled lines

(i)     Labels - l1 to l9
The format is l, n, Space, Space,
instruction + argument.
     eg. l1  lin

[Presumably there should have been a section (ii) here,]
[with the syntax for labels l10 -l99, but it's missing ]
[from the magazine article.                       JimG.]

Also, arguments should be preceded by a single space, in
turn preceded by the instruction.

To SAVE the ZX-CESIL 2 program, type in the following:

SAVE "cesil" LINE 4450

The program, with all variables, uses approximately 18K.
With the screen, printer buffer, etc, this expands to 25.9K.

Errors

ZX-CESIL2 generates error messages for various user errors.
The possible error/report messages are:

(i)     Data all used.
(ii)     List complete.
(iii)     Illegal label error.
(iv)     Instruction does not exist.
(v)     Command as statement error.
(vi)     Illegal use of argument error.
(vii)     Space missing error.
(viii)     Label missing error.
(ix)     Illegal operand.
(x)     Number out of range error.
(xi)     Location missing.
(xii)     Invalid location.
(xiii)     Missing quote error.
(xiv)     Invalid text error.
(xv)     What?
(xvi)     Statement as command error.
(xvii)     No more program room.
(xviii)     Data invalid.
(xix)     First 20 items of data only accepted.
(xx)     No hal instruction.
(xxi)     Last line reached or hal executed.
(xxii)     Called label does not exist.
(xxiii) Arithmetic overflow.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
INSTRUCTION  PURPOSE           ARGUMENT TYPE

add          addition                a
div          division                a
hal          halt execution          n
in           input from data         n
jin          jump if negative        b
jiz          jump if zero            b
jum          jump                    b
kin          input from keyboard     n
lin          start new line          n
loa          load a number           a
mul          multiplication          a
out          output                  n
pri          print                   c
sto          store                   d
sub          subtraction             a
;            comments                e

ArchiveZip file with TAP prepared by Jim Grimwood