Rombo Vidi-ZX

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.).



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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.



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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.



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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).



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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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