Subject: MIPS R3000 tasks available; volunteers?

From: [email-masked] (Neil Russell)
Date: Mon, 21 Jun 93 20:50:25 PDT

We need volunteers to design various part of the hardware.  Below is a list
of tasks that need doing.

Most correspondence should be directed at the mailing list:

	[email-masked]

Anything is open for discussion including the choice of CPU.

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*  CPU, peripheral controller and memory
		Allocated to: [email-masked]
	There is no problem getting CPUs.  The memory design is a function
	of what memory controller is available.  At this stage I am aiming
	at using the IDT 79R3730.  To this end I am calling IDT to attempt
	to get advance information and samples.  When I get better information,
	most other developers will get the data sheet from me to allow design
	of their respective interfaces to this chip.

*  Keyboard controller / NV-RAM / RTC
		Allocated to: <no-one>
	Research needs to be done on what is available, its cost and
	then the design of the appropriate circuit.  These devices would
	be connected to the 8-bit bus of the 3730; they would be selected
	with a chip-select and possible several address bits.

*  ISA bus
		Allocated to: <no-one>
	This one is hard.  An interface from probably the B bus of the
	3730 to the ISA backplane needs to be researched and designed.
	I figure that an ASIC for doing this such as found on any
	motherboard these days, along with the associated interface
	logic to convert R3000 control signals to x86 signals would
	be more complicated and more expensive than doing the whole
	thing in discrete logic.  Silicon Graphics Inc have information
	available on how to do this though and should be contacted.

*  SCSI bus
		Allocated to: <no-one>
	The SCSI bus would probably be done with something like a
	NEC 53C94 SCSI controller.  Research needs to be done on this
	and other available SCSI chips.  

*  Serial port
		Allocated to: <no-one>
	Some sort of serial ports should be investigated to be connected
	to the A bus of the 3730.  NS16550's would be appropriate
	but other ideas might be looked into.

*  Ethernet port
		Allocated to: <no-one>
	It has been suggested that we use an Am7990 (Lance) Ethernet
	controller.  I know nothing about this chip.  I expect that it
	could be connected to the 8-bit or 8/16-bit bus of the 3730.

*  Video
		Allocated to: <no-one>
	The IDT 79R3730 handles the DMA of rasters from DRAM and the
	serialization into 1, 2 or 4 bits per pixel.  This could be
	buffered to form 8-bits per pixel then fed into a suitable
	colour palette.  Then all that remains is to generate the
	pixel clock and the appropriate sync signals.  The sync stuff
	could come from a motorola 6845 or the like.  Because of the
	3730, this section should be real cheap.  If it doesn't turn out
	that way, then we should abandon this for some video controller
	on the ISA bus.  Resolutions up to 1280x1024x256 should be
	supported.

*  Diagnostics / monitor code
		Allocated to: [email-masked] and <someone else>
	Some initial code needs to be written to test the board and
	load the operating system.

*  Cross assembler/compiler system
		Allocated to: <no-one>
	Someone needs to compile GCC/GAS/GLD on a x86 system to cross
	compile code for the R3000.

*  Organize the schematics from the various designers.
		Allocate to: [email-masked]
	This one is an interesting one.  What we need is a free CAD
	system to do schematic capture.  Someone what to write one
	by next week? :-)  My alternative suggestion is to use something
	like xfig or even to hand write them and send them to me.
	Alternatively, I use Protel; if anyone has that, then just
	send the schematic files.

*  Printed Circuit Board design
		Allocated to: <no-one>
	I will be happy to design the board.  As I mentioned above,
	I use Protel.  If someone has better, then are certainly welcome
	to design the board.

-- 
Neil Russell		(The wizard from OZ)
Pyramid Technology			Email:  [email-masked]
3860 N. First Street			Voice:  (408) 428-7302
San Jose, CA 95134-1702			  FAX:  (408) 428-8845

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From: Patrick Mackinlay <[email-masked]>
Date: Tue, 22 Jun 1993 14:14:06 +0800 (WST)

>Most correspondence should be directed at the mailing list:

May I suggest getting your mailing list software to include a "Reply-to:"
field? Makes following up a little easier.

>	at using the IDT 79R3730.  To this end I am calling IDT to attempt

Just a comment here: having been in the same boat before waiting for IDT
to produce the R372x series of chips, I'd have to say that this chip is
going to be the most critical one in the whole design. Hopefully they
will produce this and make it available as planned...

>*  Keyboard controller / NV-RAM / RTC

I might just try and take this up. You mentioned the 8051 in your
previous mail, but I have a little further info. The original PC and XT
used the 8051, but all machines since have used the 8041. I know that
AMI (the BIOS people) make them pre-programmed with their PC BIOS (ie:
it's an EPROM as well), and think that this would make a nifty device
if we could get hold of it. It would obviously require re-burning the
EPROM, but I think it might be a good way to cut down on a couple of
chips. As for the NV-RAM and RTC, everything I've ever heard points to
Dallas Semi. Unfortunately, I've also heard that they advertise lots of
stuff that they never actually make. I'll look into both of these, and
see what I can come up with.

>	and other available SCSI chips.  

Ok, I'm probably one of the people who pushed for this. The other SCSI
chips I've had a look at include: NCR53C7xx series (SMT and _big_),
NCR538x series (pretty dumb) and the WD33C98(?) (very buggy). One
advantage of the '94 is that it's second sourced by Emulex, NCR and
Motorola, so it should be pretty easy to get hold of. You should also
note that there's a 53CF94 which is the same device but does FAST SCSI.
Again, there are '96 chips which do wide SCSI (I think). I've been
unable to get any hard data down here though...

>*  Serial port

Might I suggest a Zilog SCC? I've had good experiences with these,
and they give you the ability to use AppleTalk (physically, anyhow)
at some stage. IMHO, we should have one SCC (or something) chip on
the motherboard itself, and use an ISA card for more "regular"
serial chips. Comments?

>	It has been suggested that we use an Am7990 (Lance) Ethernet

I probably suggested this too, but again - I don't know much about
it. I think there's an alternative in the NSC 8390(?) used on a lot
of PC ethernet cards. As I said, I'm not qualified to give an
opinion here.

>*  Video

Ok, I've accepted this idea <grin>. Anyone know if the 6845 is up
to it? What sort of a range does it have on sync signals?

>*  Diagnostics / monitor code

I'd be very interested in doing this. Obviously (I think), we'd want
some sort of an assembler for this step. See below.

>*  Cross assembler/compiler system

I've looked at this before and I think it's relatively trivial. Getting
GAS to produce R3k binaries is going to be the most important first
step, as we'll need that for the boot/debug ROM.

Pat -- "There's only one thing left to do Mama, I got to ding a ding dang
	my dang a long ling long" (Jesus Built My Hotrod -- Ministry)
GCS d* -p+ c++ l++ m--- s+/- !g w- t- r

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From: Patrick Mackinlay <[email-masked]>
Date: Tue, 22 Jun 1993 14:14:06 +0800 (WST)