Mostly because the CPU cannot access the RAM while the refresh is taking place. it's a real timing issue. Alan -----Original Message----- From: Tony Nixon To: PICLIST@MITVMA.MIT.EDU Date: Thursday, February 11, 1999 8:01 PM Subject: Re: DRAM I wonder why they can't make a DRAM chip that has automatic refresh that is transparent to the user. It would seem more practicle. -- Best regards Tony Multimedia 16F84 Beginners PIC Tools. ** NEW PicNPro Programmer and Port Interface ** http://www.picnpoke.com Email picnpoke@cdi.com.au