Cisco 2522 - DB-15 and 10BaseT indicated are actually the same Ethernet.  You can only use one or the other.  There are 10 serial interfaces, s0-s9.  S2-s9 are low-speed and look the same as s0-s1, but they will not accept clock rate higher than 115200.  I used these low-speed serial interfaces when I configured the router as a frame relay switch.  The clock rate is set at 72000, so they would work with the high-speed (regular) serial interfaces.  The router can be configured to simulate frame relay cloud and act as a regular router at the same time.

r5#show version
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(7)T, RELEASE SOFTWARE (fc2)
Copyright (c) 1986-1999 by cisco Systems, Inc.
Compiled Mon 06-Dec-99 17:10 by phanguye
Image text-base: 0x0306C4E0, data-base: 0x00001000

ROM: System Bootstrap, Version 11.0(10c), SOFTWARE
BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE (fc1)

r5 uptime is 38 minutes
System returned to ROM by power-on
System restarted at 19:00:15 EST Sun Feb 28 1993
System image file is "flash:c2500-js-l_120-7_T.bin"

cisco 2522 (68030) processor (revision M) with 14336K/2048K bytes of memory.
Processor board ID 05375389, with hardware revision 00000003
Bridging software.
X.25 software, Version 3.0.0.
SuperLAT software (copyright 1990 by Meridian Technology Corp).
TN3270 Emulation software.
Basic Rate ISDN software, Version 1.1.
1 Ethernet/IEEE 802.3 interface(s)
2 Serial network interface(s)
8 Low-speed serial(sync/async) network interface(s)
1 ISDN Basic Rate interface(s)
32K bytes of non-volatile configuration memory.
16384K bytes of processor board System flash (Read ONLY)

Configuration register is 0x2102

r5#show flash all
Partition  Size        Used      Free     Bank-Size  State                Copy Mode
1            16384K 13500K 2883K  8192K       Read ONLY   RXBOOT-FLH

System flash directory:
File Length      Name/status
          addr             fcksum   ccksum
1    13824500 c2500-js-l_120-7_T.bin
          0x40           0x82E1   0x82E1
[13824564 bytes used, 2952652 available, 16777216 total]
16384K bytes of processor board System flash (Read ONLY)

Chip Bank Code Size        Name
1      1       89A0 2048KB INTEL 28F016SA
2      1       89A0 2048KB INTEL 28F016SA
3      1       89A0 2048KB INTEL 28F016SA
4      1       89A0 2048KB INTEL 28F016SA
1      2       01AD 2048KB AMD 29F016
2      2       01AD 2048KB AMD 29F016
3      2       01AD 2048KB AMD 29F016
4      2       01AD 2048KB AMD 29F016
Executing current image from System flash