Radisys Type 1 EPC

Embedded Personal Computer (EPC) Index
EXM - EXpansion Module 

EPC-21 / -22  Manuals  Manuals for -21 and -22 are the same.


Inserting an EPC into an EXM Carrier
Note: Make sure that power to your system is off. The EPC-23 is not designed to be inserted or removed from a live system.

Notice: Use of any of the files or information on this page is AT YOUR OWN RISK. If you want a guarantee on this stuff, seek out any repair / service company that supports EXM / EPC devices.

If you have any files or experience with these devices, please reach to Louis Ohland.

Supposedly, the -21 and -22 models were offered with:
-21 386SL-16, no 64KB cache and no 387SX
-22 386SL-25, 64KB cache, 387SX, and 0MB / 1MB / 4MB Base Memory.


EPC-16 4MB Base Memory, 0KB cache, no 387SX




EPC-22 0MB Base Memory, 64KB cache, no 387SX.



EPC-22 386SL-25, 4MB Base Memory, 64KB cache, 387SX.


Intel386 SL Microprocessor SuperSet 
KU82360SL Complete ISA Peripheral Subsystem Advance Information
KU80386SL 386SL CPU DataBook Jul92

64KB Cache
The two ICs under the center of the SIMM are the 64KB cache, CY7C195-25VC
CY7C195-25VC 64K x 4 Static RAM datasheet   

64 KB four-way set-associative write-through cache.  Memory writes from the 386SL that hit the cache (find the addressed location in the cache) also write into the DRAM.

Cached Addresses
0 to 640K are cached
640K to 1M are not cached.
1M to top of  installed memory are cached
   [except for a secondary graphics frame buffer like on the EXM-14 Live video board].

Base Memory 1MB or 4MB
1 MB uses 2 4Mb chips (256K by 18-bit banks). 40 pin chips don't use the rear-most pads.
4 MB uses 2 16Mb chips (1MB x 18-bit banks). 42 pin chips use all pads.
     Note: Documents say this memory architecture supports a 16MB SIMM. YMMD.

EPC-22 Base Memory


EPC-21 / -22 Memory Amounts 
0MB Base Memory, 2MB, 4MB or 8MB SIMM, max 8MB.
1MB Base Memory, 2MB, 4MB or 8MB SIMM, max 9MB.
4MB Base Memory,  2MB, 4MB, 8MB or 16MB SIMM, max 20MB.


Floppy Types Supported
360K, 720K, 1.2 MB, 1.44MB, and 2.88 MB. BUT... If you look at the EMC-FDM, it appears to have a max 500Kbit/s transfer rate, which suggests to me that it tops out at 1.44MB floppies.

Content created and/or collected by:
Louis Ohland, Peter Wendt, William Walsh, David Beem, Tatsuo Sunagawa, Jim Shorney, Tim Clarke, Kevin Bowling, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 06 Oct 2021 - Changes & Credits | Legal Info & Contact