網路上查到的.參考一下: 4 ~, o4 J& S4 U( z u"Diffusion ROM is based on VT change (using VT implant mask) => Hihg VT transistors not conducting, low VT ones conducting ' q8 l# e1 O- T8 K% M! T
VIA ROM is using via to "connect" or "not connect", resulting 0 and 1 ! Y; ~' ^8 p8 f8 A2 \% aVIA ROM may have bigger cell size "
Diffusion ROM通常用在exteranl ROM; Via ROM 跟metal ROM通常是應用在embedded system; Difussion ROM的應用時間是ROM code真的很成熟的時候,這樣才可以gain到體積小而不用改ROM code的優點; Via ROM更改ROM code的cost則比較小