FORTH83 by L.C. Benschop.

This is Forth83 system I wrote for the Spectrum in 1988. Some of the stuff
I copied (with permission) from Coos Haak, most notably the assembler and a
few machine code definitions. Of course I had seen the FIGFORTH source too.
It was developed on a Spectrum 128 with microdrives, but it works on the 48
as well and it can use tapes. 

This archive contains the system both as a TAP tape image file and as a
microdrive image. Both of these can be used with many Spectrum emulators.
The manual (in Dutch) is also included. I'm not going to translate the whole
thing into English, but I'll give some helpful hints so an experienced Forth
programmer can get started.

Forth screens are 1024 bytes in size and consist of 32 lines of 32
characters each. They are stored in a RAM disk (normally 10 screens on the
Spectrum 48k and 80 screens outside the normal 48k on the Spectrum 128k).
The screens can be stored on tape or Microdrive.

1 Microdrive commands.

FORMAT clears RAM disk.
0 DRIVE selects tape.
1 DRIVE or 2 DRIVE etc. selects first/second microdrive.
60 BCAL saves system (need to type HERE FENCE ! if extensions are added).
DELETE <name> deletes file.
CAT shows directory
n1 n2 PUT <name> stores screens n1 through n2 on tape or microdrive.
n1 GET <name> loads screens from tape or microdrive, starting at n1.
RUN <name> loads screens into RAM disk and starts loading them (executing
     or compiling the Forth source code contained therein).

2 The editor.

Start editing screen n1 with
n1 EDIT.

You see only 16 lines of a forth screen.

Cursor keys are CAPS SHIFT 5 through CAPS SHIFT 8
GRAPHICS (CAPS SHIFT 9) inserts a space at the cursor.
DELETE (CAPS SHIFT 0) deletes the character under the cursor.
TRUE VIDEO (CAPS SHIFT 3) inserts a line.
INV VIDEO  (CAPS SHIFT 4) deletes a line.
SYMBOL SHIFT Q goes to previous half screen.
SYMBOL SHIFT E goes to next half screen.
SYMBOL SHIFT W goes to the home position on the current screen.
EDIT (CAPS SHIFT 1) leaves the editor.


3 Something to play with.

The sequence

RUN TASM (takes quite some time)
RUN DOUBLE
RUN FLOATING
RUN TRANSCEN

gives you all the double and floating point math stuff. The & character is
the floating point indicator/exponent character. 1.2&-3 is what we would
normally write as 1.2E-3.

If you give the following sequence of commands instead, you get a nice UDG
(user defined graphics) editor.
RUN TASM
RUN GRAPHIC
RUN UED

The following programs are included.

TASM Transient assembler loader (can be removed after use).
ASSEMBLER the assembler itself.
DOUBLE double precision.
FLOATING floating point.
TRANSCEN transcendental functions.
GRAPHIC graphics.
UED User Defined Graphics editor.
UTIL decompiler.
MUSIC sound.
LOGO turtle graphics and screen drawing stuff.
TASKS some primitive multitasking words.
OBJECT object
UTIL decompiler.
META1 META2 META3 META4 meta forth source.
EDITOR editor.
