edit:
SCPH-5502 PAL
BIOS: 3.0 01/06/97 E => crc32 = d786f0b9
ID: SCEE
TEST 0x20: 97 01 10 C2
TEST 0x22: 'for Europe'
TEST 0x23: CXD2545Q
TEST 0x24: CXD2545Q
TEST 0x25: CXD1815Q

SCPH-102 PAL
BIOS: 4.5 05/25/00 E => crc32 = 76b880e5
ID: SCEE
TEST 0x20: 99 02 01 C3
TEST 0x22: 'for Europe'
TEST 0x23: CXD2940Q
TEST 0x24: CXD2940Q
TEST 0x25: CXD2940Q

it adds CD unit control commands, since cdinfo.txt
http://psx.rules.org/psxrul2.shtml
http://hitmen.c02.at/html/psx_docs.html
and this document here
http://members.at.infoseek.co.jp/DrHell/ps1/index.html
were so interesting

so one can now retrive CD unit's chipset information, SCEx code from CD/Modchip,
execute those undocumented test commands, etc.

input besides to what's given on screen:
L2 - flip lower section
R2 - flip output buffer pages
/\ - set max value ($ff)
>< - set min value ($00)
[]+DPad - do things faster
L1+R1+() - execute selected command only (otherwise it's always followed with $1a)
this is sometimes neccessary, eg. for PLAY Command to work properly
L1+R1 + rest buttons - operate with Commands instead of Parameters
(e.g. if you'd want to swap CD you could use STOP command)
SELECT - change video mode
(i'm not sure if it works since all TVs i could get to support both PAL & NTSC but at least it will change resolution
basically video mode will be set on startup based on ROM detected so likely you won't need to use this at all
but you could try if you don't get an output for example)

chip IDs i get from my SCPH-5502 are:
CXD2545Q from sub-commands 23&24. it's servo system + signal processor,
so likely 23 is for servo & 24 for sp or vice-versa
CXD1815Q from 25. this is CD-ROM decoder
subcommand 22 return: 'for Europe'
subcommand 20: 97 01 10 C2, which @DrHell's page given above is described as Year, Mon, Day, Ver and it does look so

sub-commands 60 & 71..76 look interesting, could be they return unit's internal memory content

and please be careful with 00..1a - those control drive mechanics, like you can make it spin with tray open - don't do it
only interesting ones in this range appear to be 04 & 05

so instead i've wrote program that calculates CRC directly on PSX
and compares this value against existing db: http://redump.org/datfile/psx-bios/

very easy - record CD, boot on PSX, and you'll get CRC + status: dumped or not yet
http://www.mediafire.com/?nzmttnwi0ut

didn't want to revive that theread there
and my results from SCPH-5502 are as expected anyway:
System ROM Version 3.0 01/06/97 E
CRC32: d786f0b9
so nothing new but at least i'm sure now this is a good ROM

maybe somebody else feels like checking out his system
if it turns out undumped, you could use Shendo's program then
http://forums.ngemu.com/misc-psx-discus … guide.html
or ask somebody with right equipment to do it for you