🚀 go-pugleaf

don@zl2tnm.gen.nz (Don Stokes) writes:

>jan@pallas.neuroinformatik.ruhr-uni-bochum.de (Jan Vorbrueggen) writes:
>> A number of smaller Vaxen (only the uVaxI? or also the 725/730?) didn't have
>> these and in general had to do I/O a page at a time...probably still slightly
>> faster than a PC/XT :).

>The MicroVAX I addressed memory on the Qbus, in the same way it addressed
>peripherals.  DMA is no different on these systems, except that there is no
>need for mapping registers because the memory is in the same address space
>as the peripheral and can be addressed directly.  I'm not sure about the 
>11/730, but there's nothing special about the I/O adapters -- bog standard
>Unibus devices that presumably have some sort of map into memory.

The 11/730 had mapping registers.  It's memory (MS730-CA) was same
as VAX 11/750's memory boards (MS730CA = MS750-CA 1MB bds).  The 730
had a special I/O accelerator bus for its "IDC" (Integrated Disk
Controller) on the -ZA models (the RB730).  Basically the IDC RB730
board got signals from the UNIBUS controller integral to the KA730
processor board-set but xfered data on the special accelerator bus
(there was some special microcode for those 8 4-bit AMD2901 bit slice
processors that made up the KA730 that handled these xfers).  The
KA730 did have a normal and FULL UNIBUS interface.  The backplane
of the -ZA (IDC based) model had slots (1 full function HEX, and
5 QUAD slots shared with MS730/750 boards).  You could even extend
the UNIBUS into an external BA11 chassis.  But anyway, more approprate
to this thread, the KA730's had the standard VAX UNIBUS interface with
mapping registers, et al.

The latter -CA 730's did away with the IDC/RB730 and just had normal UNIBUS
--
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Michael F. Santangelo                 + Internet: mike@cbl.umd.edu      [work]
Computer & Network Systems Head       +           mike@kavishar.umd.edu [home]
Univ MD: CEES / CBL (Solomons Island) + BITNET:   MIKE@UMUC  [fwd to mike@cbl]