PC-100

NOTE! As PC100 is getting increasingly difficult to acquire, PC133 can be used instead. Using PC133 may or may not increase the performance of your model, as some models may underclock it to their respective original DRAM speeds. PC100 This is SDRAM at 100 MHz in a 144-pin SO-DIMM form-factor.

Available DRAM modules from IBM

SDR type	Option Part Number (OPT)	Field Replacement Unit (FRU)
Non-ECC, unbuffered 1Rx16 32MB PC100 CL2	20L0253	20L0263
Non-ECC, unbuffered 1Rx8 64MB PC100 CL2	20L0254	20L0264
Non-ECC, unbuffered 1Rx8 128MB PC100 CL2	20L0255	20L0265
Non-ECC, unbuffered 2Rx8 256MB PC100 CL2	33L3069	33L3070

Models that support this technology

Models	Soldered on motherboard	SO-DIMM Slot 1	SO-DIMM Slot 2	Official Max-Memory	Unofficial Max-Memory
240X, 240Z, i Series 1124	64 or 128MB (240Z)	Depends	N/A	192 or 256MB (240Z)	192 or 256MB (240Z)3
390X, i Series 1700 i Series 1780, i Series 1781	N/A	Occupied	Depends	256MB	512MB2
570E, i Series 1157	64MB	Depends	N/A	192MB	320MB1
600X	64MB	Occupied	Depends	320MB	576MB2
A20m, A20p	N/A	Occupied	Depends	256MB	512MB2
A21e5, A21m, A21p	N/A	Occupied	Depends	256MB	512MB2
A22e5, A22m, A22p	N/A	Occupied	Depends	256MB	512MB2
A21e, A22e, i Series 1800	N/A	Occupied	Depends	128MB	256MB4
T20, T21, T22	N/A	Occupied	Depends	256MB	512MB2
X20, X21 i Series 1620, TransNote	64 or 128MB (X21)	Occupied	Depends	192 or 256MB (X21)	320 or 384MB (X21)1
S30, S31	128MB	Depends	N/A	256MB	256MB3
i Series 1200, i Series 1210, i Series 1230 i Series 1250, i Series 1260, i Series 1300 i Series 1330, i Series 1370, 130	32 (1210) or 64MB	Depends	N/A	160 (1210) or 192MB	160 (1210) or 192MB3
i Series 1422, i Series 1442, i Series 1482 i Series 1483, i Series 1492	N/A	Occupied	Depends	256MB	512MB2
i Series 1542, i Series 1562, i Series 1592	N/A	Occupied	Depends	256MB	512MB2

FOOTNOTES [Δ]

1. Attained via one 2Rx8 256MB PC100 non-ECC SO-UDIMMs, not possible with 1Rx8 256MB PC100 non-ECC SO-UDIMMs.
2. Attained via two 2Rx8 256MB PC100 non-ECC SO-UDIMMs, not possible with 1Rx8 256MB PC100 non-ECC SO-UDIMMs.
3. Attained via one 1Rx8 128MB PC100 non-ECC SO-UDIMMs, not possible with 1Rx8 256MB PC100 non-ECC SO-UDIMMs.
4. Attained via two 1Rx8 128MB PC100 non-ECC SO-UDIMMs, not possible with 1Rx8 256MB PC100 non-ECC SO-UDIMMs.
5. These are uncommon models that utilize the 82443BX memory controller, which allows them to accept 512MB of RAM in total. Not all of them come with this specific memory controller however, as some are limited to 256MB due to their 82443MX memory controller.

Available DRAM modules from other companies

Manufacturer	Partnumber	Description	Tested on model
TBD	TBD	TBD	TBD