David Wilson wrote:
aiiadict@gmail.com wrote:the IOU and MMU are custom logic chips that select different circuits depending on address inputs.......what else?The IOU & MMU also implement the Apple IIe soft switches used to control video display modes, main vs aux RAM read/write usage, 16K Language card emulation, C100-CFFF ROM space selection, cassette output etc etc
Including pushbutton inputs and annunciator outputs, which are very dear to me. ;-) Making a feature-for-feature and bug-for-bug clone would be a difficult project without more design information. -michael NadaNet networking for Apple II computers! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it's seriously underused."