Cisco 2504 - The diagram indicates DB-9 (token ring) which is correct, even though the port shown is DB-15.  The left most RJ-45 port is BRI.

r3#show version
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-JS-L), Version 11.2(22), RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2000 by cisco Systems, Inc.
Compiled Mon 03-Apr-00 21:13 by htseng
Image text-base: 0x03040380, data-base: 0x00001000

ROM: System Bootstrap, Version 5.2(8a), RELEASE SOFTWARE
BOOTFLASH: 3000 Bootstrap Software (IGS-RXBOOT), Version 10.2(8a), RELEASE SOFTWARE (fc1)

r3 uptime is 20 minutes
System restarted by power-on
System image file is "flash:c2500-js-l_112-22.bin", booted via flash

cisco 2500 (68030) processor (revision L) with 6144K/2048K bytes of memory.
Processor board ID 05275671, with hardware revision 00000000
Bridging software.
SuperLAT software copyright 1990 by Meridian Technology Corp).
X.25 software, Version 2.0, NET2, BFE and GOSIP compliant.
TN3270 Emulation software.
Basic Rate ISDN software, Version 1.0.
1 Token Ring/IEEE 802.5 interface(s)
2 Serial network interface(s)
1 ISDN Basic Rate interface(s)
32K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read ONLY)

Configuration register is 0x2102

r3#show flash all

System flash directory:
File Length    Name/status
          addr           fcksum    ccksum
1    8128764 c2500-js-l_112-22.bin
          0x40         0xB17D   0xB17D
[8128828 bytes used, 259780 available, 8388608 total]
8192K 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
Executing current image from System flash