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Description of the 68030 based system
Vidéo purchase
Evolution of the système


The ancestor of this system dates the time in which it was necessary to spend a fortune to have an information system of development deserving of this name (years 83/84). It was a question to have a tool of development for microcontrollers of the family MOTOROLA (put into series MC680X for the specialists) to realize "fiddle" electronics more original than eternal audio amplifiers and other gradators published in the specialized reviews.

This drove to the realization of a system with MC6809's base containing a KiloOctets RAM board, a compatible Péritel video board (a television acting as video display) and a tape recorder interface to save various programs. Basic software was contained in a 2 Koctet ROM(of type 2716 for the same specialists) and contained mainly the management of the screen (25 lines of 40 columns), a text editor and the routines of serial connection for the tape recorder. First recorded software was obviously the assembler 6809 then came the assemblers of the microcontrollers and the various programs associated to various applications.

Then, arrived the 3" 1/2 floppy disk reader which allowed to save more easily data but by introducing a difficulty: the necessity of having a files and repertoires management software.

The assembly language, although very effective to pull the maximum of performances of a some microprocessor, showed himself fast little adapted for the development of more and more complex software packages.

I asked then the following question: which compiler of high-level language am I going to have to develop?

One spoke then at the time of a semi-compiled language easily developping by a single person because, contrary to assembler or other Pascal and C languages, compilation makes only in a single pass without requiring the creation of a labels table: the FORTH. The other enormous advantage at these times when size memory was something relatively weak, the kernel including the compiler and the interpretor could be contained in a space lower than 16 KiloOctets! Knowing that a processor of type MC6809 can not administer directly more than 64 KiloOctets, this language allows to have a complete information system in this space.

One thousand congratulations to Charles MOORE who invented this fabulous language at the beginning of the 70s!

This gave such a flexibility to the system as it became there fast the main subject of "fiddle" with evolution of the processor towards a MC68000 then a MC68030 and development of several interfaces as a graphics board VGA 640x480 (from which arise the screen views) and an SCSI interface allowing the connection of a hard disk, a ZIP reader (goodbye 3"1/2 floppy disks) and even of a CDROM reader!

Description of the 68030 based system

System in the current state is builded around a MC68030 pu rhythm with a 40 megacycles frequency clock. This frequency can seem exceeded toward the PENTIUMS or the other G4s curling GigaHertz, but it is necessary to know that FORTH is an informatics language which, due to the concept, is very close to the assembly language, what allows the software developernot to ask too much the question to know if it has to pass in machine language for the most par of applications.

Without too much entering the detail, one can describe the main constituents distributed on several cards:

The processor board

  • MC68030 to 40 MHZ.
  • 32 KiloOctets ROM including the real-time kernel, the FORTH compiler / interpretor, the graphics board management subroutines with multi-window, the access routines to the various filessystems for the starting up.
  • RAM with zero wait state cycle organized in 512 KiloMots of 16 bits and fate to be received the contents of the ROM as well as the set of the software packages of which you saw outlines.
  • RAM with 2 wait state cycles organized in 512 KiloOctets and fate to be completed the previous one for less successful programs (if the place was insufficient, the games software packages could be there settled without one realizes the difference).
  • Management of a keyboard, a serial connection puts RS232 and of the clock of the real-time kernel by a compatible peripheral circuit 680x0 (MC68681 for the specialists). Software can administer until 64 tasks which can have each a different priority level (I do not exceed about twenty tasks with the set of existing applications and still it is necessary to activate them by opening their respective windows). Every task is scrutinized all the millisecondes what gives to the system a very fast response time.
  • A compatible bus 6800 to pilot the other boards through a back panel board.
The interfaces board
  • An SCSI-1 interface ( 8 bits) allowing to connect an internal HARD DISK, an internal CDROM reader accepting PC standard, a ZIP IOMEGA reader in external (goodbye 3"1/2 disk reader) and even a SCANNER (AGFA's Snapscan 310) of which software is in the course of development (one can another add 3 other ring peripherals on this bus).
  • A parallel interface CENTRONICS for the printer (BJC4000 of CANON). It is to note that printing is administered in task of not priority bottom what leaves the maximum of power of the available processor at any time.
  • An mouse interface of type ATARI (it was the least expensive at the time).
The video board
  • It is built around the simple sweeping circuit (MC6845 for the specialists) sharing access to the memory of screen with the processor which executes all the graphic routines. The clock frequency is 25 MHZ what allows to have a compatible video VGA there 640x480. The number of shown colours is 128 what explains the framage process used to feign more tint (womb of 8x8 for the specialists).
The dynamic RAM board
  • It uses 8 modules of 1 Méga Octets of which 1 is reserved in variable various programs, the 7 others allowing to arrange a virtual disc for files plugs.
The video purchase board
  • This board has a static RAM of 128 KiloOctets allowing to protect a complete video weft samples of which arise from an analogic to digital converter 8 bits put rhythm to 12 MHZ (TDA8708 for the specialists). One of applications other than the seizure of image can be decoding Teletext.

It is necessary all the same to insist on the fact that the performances of this system can not reach that of PC or curren MAC but it is necessary to not forget that he was in its entirety conceived by a single person. In its entirety conceived implies the conception of hardware AND software!


Example of an occupied well desk:

Animation software for 3 dimensions objects:

Software of display of the video lines (numbers 1 to 625 in SECAM or PAL and of 1 to 525 in NTSC):

Video purchase

SECAM pictures:

PAL pictures:

NTSC pictures (digital camera with video NTSC output: VIVITAR VIVICAM 2000):

Evolution of the system

Further to a discussion with working colleagues, it turns out that I found two of them particularly interested by the system described in this site:

  • A development engineer specialized in DSP software packages for radiocommunications, who proposed for the realization of a printed circuit in the size of PC boards in progress,

  • A development engineer specialized in FPGA design in VHDL language and seduced by the FORTH language, suggests simply building a processor FORTH allowing the realization of basic instructions in a single cycle of clock. He is realizing the FPGAs code for the new board.

I thus created an web site in order to make known the system in the world.

A web surfer, enjoyed by the system, have suggested to me to make a light version of it: the FORTH mini system.

The FORTH is a language very close of the machine, the bes thing is to build a processor containing the basic instructions of this language as the FORTH core.