Rombo ZX Manual

RomboZX.txt

		 VIDI
	ROMBO PRODUCTIONS
	
	
	

		VIDI-ZX

	VIDEO DIGITISER FOR ZX-SPECTRUM


Copyright 1988, ROMBO Productions.



			Credits :


			Hardware	Colin Faulkner
			Software	Marcus Sharp




			ROMBO Productions
			107 Raeburn Rigg
			Livingston
			West Lothian
			EH54 8PH
			Tel : (0506) 39046



CONTENTS                                                          PAGE

1. INTRODUCTION
        1.1 Items Supplied .......................................... 1
        1.2 Hardware Requirements ................................... 1
        1.3 VIDI-ZX Overview ........................................ 1

2. GETTING STARTED
        2.1 Connecting Up ........................................... 2
        2.2 Loading the Software .................................... 2

3. USING VIDI-ZX
    3.1 Grab/Run .................................................... 2
    3.2 Shades On/Off ............................................... 2
    3.3 View ........................................................ 2
    3.4 Menu ........................................................ 3
    3.5 Load ........................................................ 3
    3.6 Save ........................................................ 3
    3.7 Copy ........................................................ 3
    3.8 Menu-2 ...................................................... 3

4. TECHNICAL DETAILS
    4.1 Troubleshooting and Video Cables ............................ 4
    4.2 DISCiple interface and VIDI4 program ........................ 4
    4.3 Using Microdrives and other Storage devices ................. 4
    4.4 The Machine Code program .................................... 5
    4.5 Driving VIDI from your own BASIC program .................... 5
    4.6 Backing up the VIDI software ................................ 5
    4.7 Technical Support ........................................... 5

VIDI-ZX                                                          VIDI-ZX

1. INTRODUCTION

1.1 Items Supplied

        Your VIDI-ZX pack should contain :- VIDI-ZX interface,
        Software on tape or disc and this manual.

1.2 Hardware Requirements

        To use VIDI-ZX you will need a Spectrum 48k, 128, +2 or +3. A
        video source is also required. This can be a Video Recorder,
        Camera (Black and White or Colour) or any Composite Video
        Signal (usually marked as Video Out). A suitable cable is
        also required. (SEE Technical details)

1.3 VIDI-ZX Overview

        VIDI-ZX is a Video Digitiser. This means that it is able to
        scan signals from a Video Source and represent them on the
        Spectrum display. VIDI-ZX is a frame-grabber, taking a single
        frame in full flight. This means that a still frame is not
        necessary to get a good picture.

        VIDI-ZX represents each point on the picture (or Pixel) as
        either black or white. It can also use a stipple method to
        produce an intermediate grey.

        Software is included to easily grab a picture, load and save
        and print (Using the Spectrum's COPY command).

        VIDI-ZX produces screen files suitable for use in all the
        major Spectrum art and design packages, or can be loaded
        eaSily in the user's own programs.

        Full details are included to allow you to drive the VIDI-ZX
        hardware from within you own customised programs. VIDI-ZX is
        easily configurable to work with other storage devices
        (DISCiple interface, Microdrives etc.).

                                    1

VIDI-ZX                                                          VIDI-ZX

2. GETTING STARTED

2.1 Connecting Up

        Connect the VIDI-ZX interface to the Expansion Connector at
        the back of your Spectrum.
IMPORTANT:
        NEVER CONNECT OR REMOVE THE VIDI-ZX INTERFACE WITH SPECTRUM
        POWERED UP - YOU WILL DAMAGE YOUR COMPUTER.

        Connect the Video Lead to the Socket on the side of VIDI-ZZ
        and the other end to the Video Out on the video source.

2.2 Loading the Software

        Load the tape in the normal way by typing LOAD"" . The first
        program is VIDI (BASIC) and then VIDCODE (Machine Code). The
        programs are recorded twice on the same side of the tape.

        N.B. If you are using the DISCiple interface see Technical
        Details for details of using the different VIDI4 program.

3. USING VIDI-ZX

3.1 Grab/Run

        You should now be watching the Spectrum screen displaying your
        video picture (if not then SEE Troubleshooting in the
        Technical Details section).

        The VIDI program has a MENU bar along the top of the screen.
        Options are selected by pressing the letter in brackets. For
        example the first option is (G)rab. Press G and the picture
        will freeze (or be grabbed). The Option now says (R)un. Press
        R to action it.

3.2 Brightness Control

        The orange knob on the side of the VIDI-ZX is the Brightness
        Control. Adjust it by turning to get the best Picture.

3.2 Shades On/Off

        The (S)hades On/Off option selects either 2 or 3 shaded
        pictures. Remember the option is to change the current mode -
        so when you actually have shades on then the menu will say
        (S)hades Off, as that is the next option.

3.3 View

        (V)iew if selected will remove the menu bar and show the
        entire screen. This is useful to see how the whole screen
        looks. The menu options operate exactly the same regardless of
        whether the View is on or off. Press V again to redisplay the
        menu.

                                        2

VIDI-ZX                                                          VIDI-ZX

3.4 Menu

        The (M)enu option will take you to the 2nd menu. This is used
        for loading, saving and printing. When you move to this menu
        the picture is automatically frozen.

3.5 Load

        (L)oad will load a previously saved picture to the screen.
        Press L then respond to the request for a filename in the
        normal way. If no filename is entered then the command is
        cancelled.

3.6 Save

        (S)ave works in the same way as load, except it saves the
        current screen to tape or disc. Only the picture information
        is saved and not the attributes.

        If for any reason an error occurs and the program stops - type
        RUN to return to the save and Load menu.

3.7 Copy

        (C)opy activates the built in COPY command. Remember this only
        prints the tcp 22 lines and not the bottom two lines on the
        screen.

3.8 Menu-2

        The final option is (M)enu again. This will return you the the
        lst menu bar.

                                        3

VIDI-ZX                                                          VIDI-ZX

4. TECHNICAL DETAILS

4.1 Troubleshooting and Video Cables

        If you have the software loaded and the menu showing, but no
        Picture then check :-

        1. Brightness control on the VIDI-ZX interface, turn it both
        ways to see if a moving picture is actually there. NOTE : when
        adjusting the Brightness control the menu should say (G)rab
        and NOT (R)un.

        2. Video Source - the Video Out should be connected to
        VIDI-ZX, make sure the video is switched on and playing!

        3. Video Lead - most videos have the Video Out on a BNC
        connector, in this case you will need a BNC to PHONO lead
        (available from ROMBO at £3.95 inc). Some older videos have a
        PHONO socket on the Video Out, others (especially in Europe)
        have a SCART connector - in these cases consult your video
        dealer for a suitable cable, remember that the connector on
        the VIDI-ZX is 'PHONO'.

        4. Check the small link on the VIDI-ZX at the back of the
        edge connector. It should be on the inner two pins if you are
        using the VIDI program - or the Outer 2 pins if you are using
        VIDI4, see DISCiple interface below. If the link is
        disconnected the VIDI-ZX will ignore all request signals.

        5. Phone ROMBO technical support.

4.2 DISCiple interface and VIDI4 program

	VIDI-ZX uses address line 6 for its control. This is also used
	by the DISCiple interface. To ensure compatibility there is a
	small link on the VIDI-ZX by the back of the edge connector.
	This is normally on the inner two pins for the VIDI program
	using address line 6.

	To use address line 4 change the link to the outer two pins.
	You will also have to load in the VIDI4 program and not VIDI.
	VIDI4 and its code is recorded twice on the tape after the two
	recordings of the VIDI program.

	If the link is removed then VIDI-ZX will effectively be
	transparent to the system and will not respond to any signals.

4.3 Using Microdrives and other Storage devices

	The Save and Load options are situated at the end of the VIDI
	BASIC program. These can be easily edited to suit microdrives
	etc. The program should be resaved to start at line 20
	(i.e. SAVE "VIDI" LINE 20).

                                        4

VIDI-ZX                                                          VIDI-ZX

4.4 The Machine Code program

        The routines to operate the VIDI-ZX hardware are written in
        machine code. They have been split up into small modules or
        subroutines. Each subroutine controls a specific function of
        the VIDI-ZX.

        The Subroutines are as follows : (the VIDCODE should be loaded
        in at address 32768 it is not relocatable - CLEAR 32767 first)

        If start is 32768 then
        INITIALISE      = START+0       - Initialises the interface
        SYNC            = START+3       - Grabs a frame after a sync
        FETCH           = START+6       - Reads the frame from VIDI-ZX
        VIEWSWITCH      = START+9       - Switches the menu bar on/off
        STORE           = START+12      - Stores the screen
        RETRIEVE        = START+15      - Retrieves the screen
        FETCHSTIPPLE    = START+18      - Reads a stippled frame
        STIPPLE         = START+21      - Stipples a shaded screen
        FILTERVAR       = START+24      - 0=2 shade,  1=3 Shade
        VIEWVAR         = START+25      - 0=menu   1=full screen
        SYNCFLAG        = START+26      - 0=sync   1= no sync

4.5 Driving VIDI from your own BASIC program

        It is not difficult to drive VIDI from BASIC with the VIDCODE
        (or VIDCODE4) machine code loaded at 32768, and the addresses
        set up with BASIC LET statements. Look at the VIDI BASIC
        program to see the technique used.

        The INITIALISE routine must be called at the start.

        To get a picture make sure to POKE,VIEWVAR=0, POKE
        FILTERVAR,0 [or 1], call SYNC to synchronise on the next video
        Picture, if PEEK(SYNCFLAG) = 0 then call (RANDOMIZE USR) FETCH
        (or FETCHSTIPPLE if FILTERVAR=1)

4.6 Backing up the VIDI software

        The VIDI software is unprotected and should be backed up
        straight away. The easiest way is to run the program, press
        BREAK then :

                SAVE "VIDI" LINE 20
                SAVE "VIDCODE" CODE 32768,1000

4.7 Technical Support

        Technical support is available from ROMBO Productions. During
        office hours phone (0506) 39046, or write to :

ROMBO Productions, 107 Raeburn Rigg, Livingston, West Lothian EH54 8PH

        GOOD LUCK! and HAPPY DIGITISING!

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