PC-100

PC-100 This is 100MHz SDRAM memory in 144-pin SO-DIMM form-factor.

Available memory types from IBM

Partnumber	FRU	Description
20L0253	20L0263	32MB PC100 SDRAM NP SO-DIMM
20L0254	20L0264	64MB PC100 SDRAM NP SO-DIMM
20L0255	20L0265	128MB PC100 SDRAM NP SO-DIMM
33L3069	33L3070	256MB PC100 SDRAM NP SO-DIMM

NOTE!

As PC-100 memory is getting increasingly difficult to aquire, PC-133 memory may be substituted on some models. Using PC-133 memory will not increase system performance, as it will be run at only PC-100 speed. PC133 memory cannot be used on T20, T21, or T22 models.

ThinkPads that support this technology

ThinkPad Models	Soldered on systemboard	DIMM Slot 1	DIMM Slot 2	Official Max-Memory	Unofficial Max-Memory1
240X	64MB	Empty	NA	192MB5	256MB
390X		Occupied	Empty	512MB2	Unknown
570E	64MB	Empty	NA	320MB6	Unknown
600X	64MB	Occupied	Empty	576MB3	Unknown
770X	64MB	Occupied	Empty	Unknown	448MB7 or 512MB2
A20m, A20p		Occupied	Empty	512MB2	Unknown
A21e		Occupied	Empty	256MB4	Unknown
A21m, A21p		Occupied	Empty	512MB2	Unknown8
A22e - Celeron		Occupied	Empty	256MB4	<384MB
A22e - Pentium III		Occupied	Empty	512MB2	Unknown
A22m, A22p		Occupied	Empty	512MB2	Unknown
S30, S31	128MB	Empty	NA	256MB5	Unknown
T20, T21, T22		Occupied	Empty	512MB2	Unknown
TransNote	64MB	Empty	NA	320MB6	Unknown
X20	64MB	Empty or 64MB DIMM	NA	320MB6	Unknown
X21	64 or 128MB	Empty	NA	320MB or 384MB6	Unknown
i Series 1200	32 or 64MB	Empty	NA	160 or 192MB5	PC133/256MB6
i Series 1210	32MB	Empty	NA	160MB5	Unknown
i Series 1230, i Series 1250, i Series 1260	64MB	Empty	NA	192MB5	Unknown
i Series 1300, i Series 1330, i Series 1370	64MB	Empty	NA	192MB5	Unknown
i Series 1422, i Series 1442, i Series 1482, i Series 1483, i Series 1492		Occupied	Empty	256MB4	Unknown
i Series 1542, i Series 1562, i Series 1592		Occupied	Empty	256MB4	Unknown

FOOTNOTES [Δ]

1. See Unofficial_maximum_memory_specs
2. Based on 2x 256MB DIMMs, might require removal of original base memory
3. Based on base 64MB plus 2x 256MB DIMM in Slots 1 and 2
4. Based on 2x 128MB DIMMs, might require removal of original base memory
5. Based on base memory plus 128MB DIMM in Slot 1
6. Based on base memory plus 256MB DIMM in Slot 1
7. Based on Mac-How
8. Based on base 64MB plus 1x 256MB and 1x 128MB DIMMs in Slots 1 and 2
9. Intel 440BX motherboard accepts up to 128 Mbit (not Mbyte) chips on the SODIMM, i.e.: 16MX8, 32MX4, etc. A 256MB SODIMM must have 16 visible chips to be compatible. 512MB per slot, for a total of 1GB, is theoreticaly possible; "stacked" SODIMMS with 32 128Mb chips exist, but they're rare, expensive, and may not fit in the RAM slots with the cover closed.