Cambridge Research Systems - Visual stimulators

Why do I need a ViSaGe ?

Getting from that brilliant insight to the crucial experiment can be the hardest part of any research project. The choices for visual stimulus generation can be bewildering, but false starts waste your time and money.

Computer graphics seem the obvious solution, but it's not that simple. Most systems are designed for games: they are difficult to program and unsupported. Their dynamic range is limited, with inadequate contrast and colour control, and timing is unpredictable. You need the ViSaGe advantage ...

Compare VSG Hardware

The table below lists the main VSG hardware features and illustrates the differences between the systems.

Hardware feature

VSG hardware version

ViSaGe

VSG2/5

VSG2/4

VSG2/3

VSG2/2

PC bus type

66 MHz, 64 bit, 4x AGP

33 MHz, 32 bit PCI

8 MHz, 16 bit ISA

Max. transfer rate from PC DRAM

>40 MB/s

4 MB/s

1.5 MB/s

Output resolution

14 bit

15 bit

15 bit, 8 bit

12 bit, 8 bit

8 bit
(12 bit optional)

DAC system

3 x various manufacturers

2 x ADV7162

2 x Bt460

1 x Bt459
(2nd Bt459 optional)

Graphics processor

3DLabs Wildcat VP P9

TMS34020

TMS34010

Graphics processor speed

TBC

50 MHz

40 MHz

32 MHz

Framestore - standard configuration (AKA "VideoPage" memory area)

256 MB - [1]

8 MB

4 MB

Framestore - add-on sizes

256 MB

24 MB

32 MB, 16 MB

N/A

Max. framestore size

512 MB - [1]

32 MB

68 MB (2 x 32 MB)

Framestore pixel size

4 bytes

1 byte or 4 bytes

1 byte

VideoPage video modes

8 bit palette
24 bit true colour

8 bit palette

Overlay plane size (AKA "OverlayPage" memory area)

16 MB

2 MB

N/A

OverlayPage pixel size

4 bytes

1 byte

N/A

OverlayPage video modes

8 bit palette
24 bit true colour

2 bit palette

4 bit or 8 bit palette,

4 bit or 8 bit palette

N/A

On-board, non-display memory (AKA "ScratchPage" memory area)

8 MB - [2]

8 MB

4 MB

ScratchPage pixel size

4 bytes or 1 byte

1 byte or 4 bytes

1 byte

ScratchPage video modes

8 bit palette
24 bit true colour

8 bit palette

8 bit palette,

8 bit palette

Local, non-display memory (AKA "HostPage" memory area)

Unlimited - [3]

HostPage pixel size

4 bytes or 1 byte

1 byte or 4 bytes

1 byte

HostPage video modes

8 bit palette
24 bit true colour

8 bit palette,

8 bit palette

Digital I/O

Ten in
Ten out

Eight in
Nine out

Five in
Nine out

Eight in
Nine out

Analog I/O

Six 16 bit in
Two 16 bit out

Five 12 bit in
One 12 bit out

Seven 12 bit in
One 12 bit out

Zero in
One 12 bit out

Hardware reaction timing
(requires CB6, CT6, CB3 or CT3 response box)

Yes

Max. pixel clock

160 MHz

150 MHz

120 MHz

108 MHz

Max. line rate

200 kHz

Max. frame rate

200 Hz

500 Hz

Support for VSGDSP

Yes

Support for RG1, RG2

Yes

Supported in VSG software version

8, 6

8, 6, 5, 4

8, 6, 5, 4, 3

Important Notes

[1] - The ViSaGe framestore is provided on a dual-head AGP graphics card. The framestore memory space is shared between the Windows desktop and the VSG Stimulus Display. This means that some of the 256/512 MB area is reserved for use by the Windows display.

[2] - The ViSaGe on-board, non-display memory space is emulated using main PC memory and is provided only for backwards compatibility. There is no additional benefit in using this memory space compared to the off-board, non-display, virtual memory space.

[3] - The off-board, non-display memory space is a virtual VSG memory area which uses main PC memory. The memory space size is dependent on the amount of free RAM in your PC.