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
網路上查到的.參考一下:+ \% `- ?! B2 Y0 V
"Diffusion ROM is based on VT change (using VT implant mask) => Hihg VT transistors not conducting, low VT ones conducting & b' I, \& o- J! l& ]% u- M3 ~: a
VIA ROM is using via to "connect" or "not connect", resulting 0 and 1 5 e7 n, F( F1 J0 o' P9 tVIA ROM may have bigger cell size "