HP 2820 - Manual (Page 291)

Memory
Product name Description Part number
Memory upgrades (DIMMs) The standard 96 MB of
memory in the device can be
expanded to up to 224 MB
using the additional DIMM slot.
32 MB
C7845A
Memory upgrades (DIMMs) 64 MB C9680A
Memory upgrades (DIMMs) 128 MB C9121A
Font DIMM (100-pin) You can install an 8-MB
language font ROM in the
DIMM slot. Visit http://www.hp.com for
DIMM availability and ordering.
ENWW Memory 275