*** 2 page review/ ???? words/ 3grabs 2Photos (in snailmail! ***

Lacescan

Broaden your horizons with this hardware project. Derryck Croker dons the
surgical gloves...

Lacescan is a development of the original Public Domain OverScan
modification and improves on both the original hardware and software. The
simplicity of the circuit belies the enhanced productivity working on a
screen with more real estate and less useless border. All it takes is two
chips, a resistor, an optional switch, and some minor surgery to the ST's
motherboard. All the components are widely available from electronics stores
(Maplin in the UK). Installation is straightforward and detailed in the
accompanying ST-Guide format hypertext but you could damage your machine so
only perform the modification if you're confident of your ability to perform
the changes detailed here. Neither the Lacescan author, myself, nor the
Atari Computing Group accept any responsibility or liability for any damage
to your machine as a result of attempting this project.

The hardware is only suitable for ST machines due to changes in the hardware
design in STe machines but STe owners can use the large screen emulator
software, so do read on...

The circuit can either be built on stripboard or by piggy-backing the chips
on top of others on the motherboard - as suggested in the ST-Guide
hypertext. I designed a custom printed circuit board (PCB) which is included
on the reader disk ready for printing to drafting film and photoetching.

*** LACE_PCB.GIF here ***

Tiptoe through the tulips
This is the scary bit. We have to follow the Display Enable signal generated
by the Glue chip and interrupt it by cutting through some tracks in order to
introduce our little gadget, a sharp craft knife is the ideal tool.
Soldering the wires to the vias (where tracks pass from one side of the
motherboard to the other) poses less risk of the fine tracks lifting.

Driving a hard bargain
Reboot your machine with the Lacescan driver and optional large screen
emulator and mouse accelerator installed in the Auto folder. Hold down the
left [Shift] key to display the initial setup screen and, using the keys
detailed, adjust the display as large as your monitor can handle without
distorting the edges of the screen. you'll probably need to re-position the
screen using the usual controls for optimum results. Some slots are reserved
to centralise the display area when using non-overscanned screens which is a
nice touch.

Bigger is better
The optional Lacescan virtual screen emulation software enables ST and STe
owners to display (amongst others) a whopping 1024x960 pixels (TT high). At
this resolution there is a speed penalty but my machine remained perfectly
usable. Each virtual screen resolution has a hot-key listed in the
LACE_EMU.INF file, users of boot managers (XBoot, Superboot) can select
resolutions by copying individual DEF files. Mono users may prefer to rename
GEN_MONO.INF to LACE_EMU.INF - it's basically the same except the colour
monitor commands have been stripped out. A cunning piece of coding
initialises new resolutions by clicking on the 'High' button in the 'Set
Preferences' dialog so long as you're using the built-in TOS desktop. If
you're running a replacement desktop which doesn't include this option you
have to quit to the built-in desktop or reboot with the required emulation
set. MagiC users running MagXDesk, Thing or other suitable desktops can use
the 'Change Resolution' dialog. Once an emulation is active the SET_LACE.ACC
desktop accessory can be used to tweak the results or load other emulations
as desired.

The bottom line
Most software written to GEM guidelines will run at any screen resolution.
Some older software does not work properly and I was disappointed to find
the Calamus 1.09N icon toolbox was garbled in both overscan and emulation
modes.
Lacescan attempts to overcome problem applications by providing a hot-key
command to switch the overscan mode off but on my ST this only synchronises
properly on running a program - not so easy when you can't see the desktop!
This may be nothing more than the usual variations between machines but the
presence of a utility called LACE_LOK.PRG in the tools folder suggests the
problem is more widespread. This utility can be assigned to a function key
for easier access to restore stability and it worked fine on my machine. I'm
happy to report LaceScan works perfectly with the popular NVDI and MagiC
system enhancements, the latter's 'Tidy' menu item providing an alternative
to the function key workaround.
The latest version is available from BBSs connected to the FanFiles network
or from the author's webpages.

*** Boxout 1 ***
Alternatives

Overscan
Overscan is a simple design offering no emulation of other screen modes and
is available from most PD/Shareware libraries and online services.

AutoSwitch OverScan
This commercial version of Overscan includes additional programming which
automatically deactivates overscan mode for problem programs using an INF
file to specify incompatible programs. There appears to be some unresolved
compatibility issues when used together with MagiC.
*** BC on ***
OverScan GMBH
http://www.overscan.com/
Price: 90DM (around œ35)
*** bc off ***
*** end boxout 1 ***

*** Boxout 2 ***
What's overscan? Overscan is the difference between the standard screen
sizes for the three resolutions the ST can produce (ST low, medium and high)
and the maximum that can be displayed on a particular monitor. The
difference is the familiar 'wasted' black border around the display area.

Some users adjust the display area to fill the screen (displaying the
standard number of pixels at a larger size). The overscan concept fools the
video shifter chip into displaying a bigger screen by lengthening the
Display Enable signal, switching from displaying palette 0 (the palette for
the familiar black border) earlier and later in the cycle to video memory.
This results in an 'overscanned' screen containing more pixels.
*** end boxout ***

*** product boxout ***

Lacescan

Author: Ulf Ronald Andersson
Email: dlanor@oden.se
URL: http://www.oden.se/~dlanor/
Pros: Cheap, fully configurable, emulation of non-native resolutions
Cons: PCB track cutting and soldering skills required, some STs may have
difficulty in regaining video synch on switching overscan.
Score: 80%

*** end boxout ***

*** (PHOTO) ***
Interior layouts vary between STs, take care to follow the hypertext
carefully. Check twice, cut once!

*** (PHOTO) ***
The LaceScan module fits neatly on top of the modulator using double-sided
sticky foam tape.

*** BEFORE.GIF ***
Once last look before most programs breakout into resolutions above
640x400 forever!

*** OVERSCAN.GIF ***
Overscanned at 672x480 resolution, the maximum size depends on your
machine/monitor combination - your mileage may vary...
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EOF