SASI-Infos

  • Hatte gerade mal wieder Infos zu SASI gesucht und dachte mir, ich stelle das mal hier ein, da es doch manchmal "doof" ist, wenn man was sucht. Die wichtigsten Infos habe ich mal herausgeschrieben, da ich Infos eigentlich immer gern im Textformat habe.


    -- Klaus



    Taken from Shugart SA1400 document:


    SASI - Shugart Associates System Interface


    The SASI bus structure consists of nine control lines and nine data lines on a 50-pin bus.
    All bus lines are implemented as low-true signals.


    (Odd lines are ground)


    2 DB(0) Data bus 0
    4 DB(1) Data bus 1
    6 DB(2) Data bus 2
    8 DB(3) Data bus 3
    10 DB(4) Data bus 4
    12 DB(5) Data bus 5
    14 DB(6) Data bus 6
    16 DB(7) Data bus 7
    18 DB(P) Data bus parity-odd
    20-30 - Spare
    32 ATN Attention
    34 - Spare
    36 BSY Busy
    38 ACK Acknowledge
    40 RST Reset
    42 MSG Message
    44 SEL Select
    46 C/D Control/Data
    48 REQ Request
    50 I/O Input/Output


    Line Definitions


    DB(0-P) These eight bi-directional lines plus optional parity are used
    to transfer 8-bit parallel data to and from a host adapter.


    BSY is asserted in response to the SEL line from the host;
    it indicates that the SASI bus is in use.


    ACK is asserted in response to the REQ line from the host; it is an
    acknowledgement by the controller that the host wants to perform
    a REQ/ACK handshake


    RST resets the controller by returning the microprocessor in the
    controller to the beginning of its microcode


    MSG Asserted by the controller to indicate that a command is complete.
    It is always followed by the assertion of I/O and REQ.


    SEL is asserted by the host in order to select a controller.


    C/D When asserted, the information transmitted across the bus will
    be the command or status bytes (i.a. "control" information).
    When de-asserted, the information will be data or sense bytes.


    REQ is a request for a data transfer; it operates in conjunction
    with I/O, C/D and MSG. When asserted and I/O is asserted, REQ
    will mean that data on the host bus is driven by the controller;
    when asserted and I/O is deasserted, REQ will mean that the data
    is driven by the host adapter.


    I/O Asserted by the controller to indicate the direction of information
    transfer on the data bus lines during a REQ/ACK handshake. I/O is
    "input" to the host, when asserted.


    Up to 5 Memory devices may be connected per controller


    For Example
    5 1/4" Floppies SA400/410/450/460
    5 1/4" Winchester SA600 Series
    8" Floppies SA801/851
    8" Winchester SA 1000/1100 Series
    14" Winchester SA4000 Series
    1/4" Tape Cartridge DEI/Archive Tape Cartridge

  • SASI und SCSI-1 sollten miteinander identisch sein. Ist nur eine Umbenennung.

  • Hier habe ich einen Schaltplan für ein SCSI-Interface mit einem 6502, im asynchronen Modus mit automatischer REQ/ACK-Handhabung: http://www.6502.org/users/andre/csa/scsi/index.html
    Da habe ich eine 80 MB Seagate SCSI-I dran betrieben, aber auch eine IBM 4 GB Ultra-SCSI-II Wide (mit Adapter auf 8-bit) - dass so etwas geht, dafür liebe ich SCSI :-)