2500 SX (250-4076)              Memory                 Faxback Doc. # 1004

Memory Chip Kits -

256K SIMMS
    √25-5135 consists of two 256K X 9 SIMM chips at 80 nanoseconds.

1MB SIMMS
     25-5137 consists of two 1 MB x 9 SIMM chips at 60 nanoseconds.

Memory Boards

     Third Party - Memory expansion can be accomplished by using a third
        party 16-bit memory board.

√ = Discontinued Radio Shack product

 ┌───────────────────────────────────┐
 │ Tandy 2500SX - Expand from 1MB:   │
 ├───────────────────────────────────┤
 │   Add to the Main Logic Board     │
 ├───────┬───────────────────────────┤
 │  2MB  │  (2) 25-5135*             │
 ├───────┼───────────────────────────┤
 │  3MB  │    25-5137                │
 ├───────┼───────────────────────────┤
 │  5MB  │  (2) 25-5137              │
 ├───────┴───────────────────────────┤
 │Use a Third Party Memory Adapter to│
 │ continue memory expansion, see    │
 │ vendor instructions for chip kits │
 │ necessary.                        │
 └───────────────────────────────────┘

INSTALLING ADDITIONAL SYSTEM MEMORY

The main logic board has 1 MB of permanently installed memory in Banks 0 and
1. Four empty SIMM sockets (Banks 2 and 3) are available for additional
memory. You can install 80 ns SIMMs, either 256KB or 1MB, in these sockets.
Banks 2 and 3 are labeled A and B on the main logic board.

Refer to the following table for the number and type of SIMMs required for
each memory configuration:

┌─────────┬───────────────┬───────────┬───────────────┐
│TOTAL    │  TOTAL NUMBER │SIMM TYPE  │  BANKS USED   │
│MEMORY   │  OF SIMMs     │           │  IN UPGRADE   │
├─────────┼───────────────┼───────────┼───────────────┤
│1.5 MB   │    2          │ 256 KB    │     2         │
│2 MB     │    4          │ 256 KB    │     2,3       │
│3 MB     │    2          │ 1 MB      │     2         │
│5 MB     │    4          │ 1 MB      │     2,3       │
└─────────┴───────────────┴───────────┴───────────────┘

Install the SIMMs as described in your SIMM kit installation guide. If you
install 256 KB SIMMs, you must remove them if you later choose to upgrade to
3 MB or 5 MB. Do not mix 256 KB SIMMs with any other type of SIMMs.

After installing the SIMMs, run the SetupSX program on MS-DOS Disk 1.
SetupSX completes the installation by ensuring that the new memory is
recognized in the system. Faxback Document # 1005 will provide specific instructions on running the SetupSX utility.


(smm 08/05/93)