4850 EP  (250-5143)            Memory                  Faxback Doc. # 1094

Memory Chip Kits:

256K SIMMS
   √25-5135 consists of two 256K x 9 SIMMS at 80 nanoseconds.

1MB SIMMS
    25-5137 consists of two 1MB x 9 SIMMS at 70 nanoseconds.

4MB SIMMS
   √25-5136 consists of two 4MB x 9 SIMMS at 60 nanoseconds.  This item
       is available through Tandy National Parts.  Contact your local Radio
       Shack to order this special item.

√ = Discontinued Radio Shack product.

┌───────────────────────────────────────────────┐
│ 4850 EP (25-5143) - To expand from 4MB:       │
├───────────────────────────────────────────────┤
│              Add to the Main Logic Board      │
├─────────────┬─────────────────────────────────┤
│     5MB     │ (2) 25-5135                     │
├─────────────┼─────────────────────────────────┤
│     8MB     │ (2) 25-5137                     │
├─────────────┼─────────────────────────────────┤
│    20MB     │ (2) 25-5136                     │
├─────────────┼─────────────────────────────────┤
│    32MB     │ (4) 25-5136                     │
│             │ Remove (4) 1MB SIMMS in Bank 0  │
└─────────────┴─────────────────────────────────┘


INSTALLING ADDITIONAL MEMORY

You can increase internal memory from its standard 4MB to as much as 32MB by
installing SIMMs, circuit boards containing RAM (Random Access Memory)
chips.  SIMM boards are available in three densities; each board can
contain 256KB, 1MB, or 4MB of RAM. SIMMs insert into sockets located on
the main logic board, or on a memory expansion board designed for SIMMs.

NOTE: The computer requires SIMMs rated at 80ns or faster.

MEMORY CONFIGURATIONS

Before installing additional memory, determine how much memory you need.
Then, consult the following table to determine the type and number of
SIMMs necessary to achieve that amount. For example, if you want a total
of 5MB of memory, you should add 1MB to the standard configuration of 4MB.

Keep these points in mind:

° Install the same type of SIMMs within a bank. Don't mix SIMMs in one bank.
The main logic board has 4MB of memory. Four empty SIMM sockets (Bank 1) are
available for additional memory. You can install 80ns SIMMs in these
sockets.

° Install the SIMMs as described in your SIMM kit installation guide. If you
install 256KB SIMMs, you must remove them if you later chose to upgrade to
8MB, 20MB, or 32MB.

SIMM CONFIGURATION

┌──────────────┬─────────────────┬────────────────┐
│ Memory Amount│     Bank 0      │     Bank 1     │
├──────────────┼─────────────────┼────────────────┤
│     5MB      │ (4) 1MB SIMMS   │ (4) 256K SIMMS │
├──────────────┼─────────────────┼────────────────┤
│     8MB      │ (4) 1MB SIMMS   │ (4) 25-5137    │
├──────────────┼─────────────────┼────────────────┤
│    20MB      │ (4) 1MB SIMMS   │ (4) 4MB SIMMS  │
├──────────────┼─────────────────┼────────────────┤
│    32MB      │ (4) 4MB SIMMS*  │ (4) 4MB SIMMS  │
└──────────────┴─────────────────┴────────────────┘

After installing the SIMMs, run the setup utility. The setup utility
completes the installation by ensuring that the new memory is
recognized in the system.  Faxback Document # 1095 will provide specific
information on using the SETUP485 utility.


(smm/jej-05/11/94)