did you try each stick one at time, in bank 0 first? one can be bad.
that is a very old laptop old DDR ram. (mostly not new but new old stock) no link where you bought your ram , it's name or its full part-numbers from your source, not stated.
finding memory that works right on old laptops, is not easy.
unless luck happens.
first of all only HP can help you, they designed it (engineered ) and built it.
The problems is manifold. (lots of things to get wrong)
first is the chips set in your PC, and then comes BIOS,support.
If BIOS does not recognize the serial ID SEEN , it can fail.
no service tag stated fully, by you, hint that P/N there on that tags tells any HP expert what's inside, (some pc have intel others with AMD processors, and use totally different memory types.
bingo this PC does.
it's not like changing knob on a toaster, not at all, memory is complex and more so back in the dark ages. of 2002,. 16 long years ago.
(line 1,3, and 5 matter big time)
http://pcdied.com/tag_service1.jpg
besides speeds, PC2100
DDR 266MHz !
your holds only 2 sticks, new PC had 1x 256MB
here is list of restrictions common on i5 processors ( wild guess)
density rules both chip and count.
front and back side has memory chips some only allow 1side.
the voltage has to match or buy dual voltages sticks.
this PC has no value on the street at all,zip.
why invest cash in this old dog? sorry, but why>?
why not go to GOODWILL store, buy 10 year newer PC for $20
even go to year 2010 , and give you and it a future..
and run w7 or newer ! that has support now.
also the video GPU may use some of this ram so if you use the wrong RAM the GPU goes dead. (no graphics to the old LCD)
most of these PC long ago burned out the CCLF back lamps.
most go dead in 5 years used, or 10 light usage.
one more reason to get rid of it.
No good OS runs on 1GB,safely.
here are the model numbers of your old PC
from, the offical HP parts surfer page, sorry that are not all the same.
HP did offer this new.
512MB, 266MHz, 200-pin, PC2100 SO-DIMM (Small Outline Dual In-Line Memory Module)
317436-001
DA728AV,
DA728AVR,
DB954A,
DB954AR,
DC583A,
DC583AR,
DC584A,
DC584AR,
DC735A,
DC735AR,
DC959A,
DC959AR,
DC960A,
DC961A,
DC961AR,
DG054A,
DG250AV,
DK587A,
DK587AR,
DK588A,
DK588AR,
DK589A,
DK589AR,
DM373AV,
DM373AVR,
DM393AV,
DM393AVR,
DM726A,
DM726AR,
DM745A,
DM745AR,
DM747A,
DM747AR
VG430AV,
VG432AV,
VG434AV,
VG436AV,
VV451AV,
WA763UA,
WA763UAR,
WA778UA,
WA778UAR,
WA779UA,
WA779UAR,
WA781UA,
WA781UAR,
WA782UA,
WA782UAR,
WA783UA,
WA783UAR,
WA784UA,
WA784UAR,
WA785UA,
WA785UAR,
WA786UA,
WA786UAR,
WA788UA,
WA788UAR,
WA789UA,
WA789UAR,
WA791UA,
WA791UAR,
WC226PA,
WC227PA,
WF604PA,
WF605PA,
WF606PA,
WF606PAR,
WF650PA,
WG367PA,
WH200UA,
WH200UAR,
WH201UA,
WH201UAR,
WH202UA,
WH202UAR,
WH203UA,
WH203UAR,
WH204UA,
WH204UAR,
WH770AV,
WH772AV,
WH830LA,
WH830LAR,
WJ369PA,
WJ842PA,
WJ843PA,
WK881PA,
WK882PA,
WK888PA,
WK889PA,
WK890PA,
WK891PA,
WK892PA,
WK892PAR,
WK893PA,
WK922PA,
WK923PA,
WK924PA,
WK925PA,
WK926PA,
WK927PA,
WK928PA,
WK929PA,
WK930PA,
WK934PA,
WL033LA,
WP636PA,
WP637PA,
WP638PA,
WP689PA,
WP690PA,
WP691PA,
WP694PA,
WP695PA,
WR644PA,
WR645PA,
WV465LA,
WV465LAR
some processors used above. (extremes to be clear)
Intel Mobile Celeron Pentium 4 processor - 1.60GHz
and
AMD Mobile Athlon XP 2200+ processor - 1.80GHz (256KB of internal L2 cache, 266MHz FSB, AMD PowerNow! technology)
what do you have series 2100 PC has many variants.!!!
for sure the MMC, memory manager must be made happy first.
or they will not run at all.
some P4 only used RAMBUS memory. (wiki problem on that)