You sure can boot from slot0: Make sure you format the compact flash card from your 3700 series router. Here is an example from my lab router
Cisco3700#dir slot0:
Directory of slot0:/
1 -rw- 13023624 Mar 01 1993 02:08:22 +00:00 c3725-ipbase-mz.123-7.T
2 -rw- 25305088 Mar 30 2002 19:32:34 +00:00 c3725-advipservicesk9-mz.123-8.T.bin
3 -rw- 21443444 Mar 03 1993 08:10:46 +00:00 c3725-advipservicesk9-mz.123-9.bin
4 -rw- 19922944 Mar 01 1993 00:13:02 +00:00 W2N-4.11-3745-B-coreiomem_19930301-001044
128079872 bytes total (48381952 bytes free)
Cisco3700#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Cisco3700(config)#boot system slot0:c3725-ipbase-mz.123-7.T
Cisco3700(config)#end
Cisco3700#wr
Building configuration...
*Apr 19 10:51:09.024: %SYS-5-CONFIG_I: Configured from console by console[OK]
Cisco3700#
Cisco3700#reload
Proceed with reload? [confirm]
*Apr 19 10:51:18.348: %SYS-5-RELOAD: Reload requested by console. Reload Reason: Reload command.
System Bootstrap, Version 12.2(4r)XT2, RELEASE SOFTWARE (fc1)
TAC Support: http://www.cisco.com/tac
Copyright (c) 2001 by cisco Systems, Inc.
c3725 processor with 131072 Kbytes of main memory
Main memory is configured to 64 bit mode with parity disabled
Readonly ROMMON initialized
program load complete, entry point: 0x80008000, size: 0xa2c0
program load complete, entry point: 0x80008000, size: 0xc6b7e8
Self decompressing the image : #################################################################################################################################### [OK]
Smart Init is disabled. IOMEM set to: 15
Using iomem percentage: 15
Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134-1706
Cisco IOS Software, 3700 Software (C3725-IPBASE-M), Version 12.3(7)T, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2004 by Cisco Systems, Inc.
Compiled Sat 21-Feb-04 02:13 by eaarmas
Image text-base: 0x60008D08, data-base: 0x6128E000
Cisco3700#sh ver
Cisco IOS Software, 3700 Software (C3725-IPBASE-M), Version 12.3(7)T, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2004 by Cisco Systems, Inc.
Compiled Sat 21-Feb-04 02:13 by eaarmas
ROM: System Bootstrap, Version 12.2(4r)XT2, RELEASE SOFTWARE (fc1)
Cisco3700 uptime is 1 minute
System returned to ROM by reload
System image file is "slot0:c3725-ipbase-mz.123-7.T" <<----
Cisco 3725 (R7000) processor (revision 0.1) with 111616K/19456K bytes of memory.
Processor board ID JMXxxxxxxxx
R7000 CPU at 240MHz, Implementation 39, Rev 3.3, 256KB L2 Cache
2 FastEthernet interfaces
4 Channelized T1/PRI ports
DRAM configuration is 64 bits wide with parity disabled.
55K bytes of NVRAM.
31360K bytes of ATA System CompactFlash (Read/Write)
125440K bytes of ATA Slot0 CompactFlash (Read/Write)
Configuration register is 0x2102
Cisco3700#
