On Tue, 20 Mar 2001, Chris Tribo wrote:

> >     b) What is the LSI L1A7242 and L1A7231?  LSI was recently bought by
> > Philips and there is
> >     little information on LSI chips.
> 
> 	As per a recent email of the thread "No heatsinks on 5000/240
> cpu?" those would be the CPU ASIC and the Motherboard ASIC. Definitely
> custom jobs specifically for DEC, not likely you will find much doco on
> either of those.

 Or the MB (memory buffer) and the MT (memory controller) ASICs.

 The MB ASIC is a 40/25 MHz (CPU/system) domain separator (basically a
FIFO).  Apart from the CPU and the cache, it's the only chip that is 40
MHz driven.  The 40 MHz clock generator is integral to the daughterboard.

 The MT ASIC is a memory controller (with all usual functions except from
driving RAS and CAS lines, which is performed by the onboard MS ASIC) as
well as a bridge between the CPU, TURBOchannel and memory. 

> > 2) The R3000 is a time multiplex 32-bit bus chip, the PGA R4400 was packaged
> > as 64bit bus, so is the bus going to the main board a 32 or 64bit path?
> 
> 	Since the 5000/2x0 ran both R3x00 and R4x00, my guess is that it's
> 64 on the CPU card and possibly _to_ the motherboard ASIC, but no further
> with the R4x00

 No idea here, but since at the time /240 was being developed, an R4K
daughterboard was already being considered the data path might either be
64-bit or 32-bit.  Given the memory controller is on the daughterboard it
really depends on how data lines are routed between the daughterboard and
memory modules.

> > 4) There is no reference to 144pin PGA R3000 packaged CPU anywhere, anyone
> > know exactly what make and model of R3000 DEC used?
> 
> 	No clue, it was probably also a custom design just for DEC.

 DEC states they used R3400.  I wasn't able to find any reference on the
chip.  I admit I haven't searched extensively, though.

> > 3) Does the SG-615P chip, on the daughter card, control the CPU frequency?
> > If so, does it also generate the clock for the main board?
> 
> 	No clue.

 No -- the board uses an own clock generator.  The CPU clock is not
available outside the daughterboard.

 Most of the info is available in "DECstation 5000 Model 240 Technical
Overview".  It's not deep enough to write any code but it definitely sheds
some light on /240's internals and may be a useful complement to other
sources of information.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +