Sensation!  (250-1650)    Video Memory Upgrade          Faxback Doc. # 1286

Note: Use (250-1082A) for memory upgrade.

Your computer has 512KB of video memory permanently installed on the main
logic board. Some programs can use additional video memory to run in
high-resolution modes. Install two video memory chip kit (250-1082A) if you
want to increase the amount of video memory on your computer to 1MB (1024KB).

Note: If you are not comfortable installing the video memory chips, your
computer dealer can install them for you.

CAUTION: Before touching electrical components, always touch a grounded
metal object to discharge static electricity from your body.

To install video memory chips:

CAUTION: Incorrect installation of the video memory chips can damage the
chips or your main logic board. Install the chips carefully.

1. Open the computer, and remove the drive tray.
2. Locate socket locations U55-U57-U59-U61 (next to battery holder)
3. Remove one chip from the antistatic packaging. Pin 1 of the chip is
   indicated by a dot or a notch on one end. The main logic board is
   labeled 1 at the Pin 1 end of the memory chip sockets.
4. Orient the memory chip so that the dot on the notched end of the chip
   aligns with the notched end of the socket. Carefully press the memory
   chip into the socket. Be sure that the pins of the chip do not bend.
5. Repeat Steps 3 and 4 for the remaining memory chips.
6. Restart the computer. The system automatically recognizes the additional
   video memory you installed.

Using an 8514/A-Compatible Video Adapter:

You can connect an 8514/a compatible adapter to the video feature connector
on your main logic board. An 8514/a adapter will co-reside with the on board
VGA circuitry, provisions for cooperative operation are built into the
8514/a board. The 26 pin pass through cable will allow the two boards to
interact with each other and display the appropriate output to a
multifrequency VGA monitor. Use the 8514/a video board only if the software
requires that specific video board type. Most video modes can be handled by
the on board VGA circuitry without the addition of another board.

The 8514/a compatible video boards usually come with the appropriate pass
through cable to connect to the VGA board. The Sensation! has a 26 pin
header connector (male) on the main logic board at location J14, this is the
video feature connector.

Memory Considerations:

The VGA-compatible video circuitry uses memory locations A0000-C7FFF for
display memory and the extended video BIOS. These are the same locations
used by a standard VGA adapter. If an EMS (Expanded Memory Specification)
driver or other device currently uses these memory locations, reconfigure
the device to use other memory locations. Contact your computer dealer or
consult your device documentation to determine the memory locations used.
For an EMS (Expanded Memory Specification) adapter, you can usually
designate the exclusions when starting the EMS driver.

The video circuitry uses memory locations B0000-B7FFF for monochrome
mapping. If your EMS software uses this memory range, either reconfigure the
EMS driver or do not switch to monochrome mapping.

Norton Utilities Reporting 256K Video Memory:

Norton Utilities does not report the correct amount of video memory in the
Tandy Sensation!. The standard VGA BIOS function that reports the amount
of memory only goes up to 256K.  The WD VGA BIOS in the Sensation! has its
own BIOS function that can report the actual amount of video memory. Norton
Utilities apparently does not use these specific BIOS functions, but instead
relies on the IBM standard BIOS function that only reports up to 256K. If
the machine is able to get into Windows/Winmate, then the video memory is
working correctly. (640 X 480 256 color mode requires 512K)

(rjs/smm-08/06/93)