Intel iapx 432 manual Transfer Mjde

iAPX 432 Interface Processor Architecture Reference Manual

DIRECl'ICN

The direction attribute specifies whether the windowed object may be read, written, both read and written, or neither read nor written. When the window is opened the IP checks the requested direction attribute with the access rights granted by the object reference. The access rights requested in the direction attribute must be equal to, or logically less than, the rights granted by the object reference. For example, if the object reference indicates t~at the object may be read, then the permi.ssable di.rection attributes are read, or neither read nor write~ requesting the ability to write, or to read and write the object would be illegal.

Orx::e a window has been successfully opened, the IP checks every subsequent subrange address reference to insure that it conforms to the direction attribute, otherwise an active window fault occurs. (The IP's read/write line identifies the type of access being attenpted. ) This perroits the IP controller to open a window for reading with the assurance that a mis-programmed DMA controller will not be able to write into it.

TRANSFER STATUS

An open window may take one of four states: o transfer in progress~

o transfer terminated by fault~

otransfer terminated by count runout~ (block mode only) o transfer termination forced~ (block mode only) •

The IP controller will open a winnow with the status attribute set for "in progress". If the IP detects a fault asscx::iated with an active window, it will change the status attribute to "terminated by fault". A randan node window which is closed (set invalid) with a transfer status of "in progress" is considered to have terminated normally since there is no means for an IP to predict when a randan mode transfer is finished. The remaining two states are associated with window 0 block IOOde transfers only and are described in section

3-3. -

TRANSFER MJDE

Windows 0 and 1 have alternate transfer nn:1es that may be selected by setting the mode attribute when the window is opened. Window 0 may be opened in block TOC>de, which permits buffered high speed transfers of contiguous blocks of data~ this is described in section 3-3. Window 1 may be opened onto the i.nterconnect address space ~ this is described in section 3-4. The transfer mode attribute has

3-6