Xref: utzoo comp.sys.amiga:65118 comp.sys.amiga.hardware:3361 Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!zaphod.mps.ohio-state.edu!van-bc! From: lphillips@lpami.wimsey.bc.ca (Larry Phillips) Newsgroups: comp.sys.amiga,comp.sys.amiga.hardware Subject: Re: Questions. (Autoconfig,RAD:,SCSI) Message-ID: <1926@lpami.wimsey.bc.ca> Date: 4 Sep 90 05:11:33 GMT Lines: 54 Return-Path: To: van-bc!rnews Such short questions, but oh so large and complex answers.... In <678@hexagon.se>, frix@hexagon.se (Fredrik Rothamel) writes: >I have a couple of questions that I hope someone could find some answers >to, or at least pointers to info about. > >1. Autoconfig (tm) > How does it work ? Briefly, a signal is sent out on the Zorro bus, which is intercepted by the first autoconfig card in the chain, and at the same time, a READ is performed. If the data from the READ makes sense, more stuff is read, and the program querying the bus knows from the data, what kind of card it is, and what resources it requires. The program then tells the card what address(es) it occupies, and the card latches that information for any further communication. At this point (give or take a few things), the card stops answering to the autoconfig address and passes the config signal on to the next card in line. This continues until there are no more cards to be config'ed. For more detailed information, see the A500/A2000 Tech Ref Manual, and the expansion.library autodocs. >2. RAD: > How does the Amiga know if and where a RAD: disk is present when > it boots ? A special structure is placed in memory. On bootup, this structure is located and acted upon, and in the case or RAD:, will cause the OS to set up a RAD: device again and protect the memory used from being stomped on. For more information, see the autodocs and includes, especially the parts about ROMTAGs. >3. SCSI > What signals does a SCSI drive need/send. 8 bits for data, and a variety of control signals. The spec for SCSI is relatively complex. Basically, the control signals determine the interpretation of the contents of the data bus, which can be taken as selection, commands, messages, status, or data. For more information, see the SCSI specification, or data sheets for any of the SCSI conttroller chips. -larry -- It is not possible to both understand and appreciate Intel CPUs. -D.Wolfskill +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+