> - we should reserve an input or two for "manufacturing" jumpers
> so that s/w can run some internal diagnostics and board test stuff
I was planning to see what was left of the I/O pins on the 3730 for
just the reason. Maybe if we run out, we need a spare PAL to implement
these plus some LEDs.
> - save a few bits to read the SIMM ID bits, so that s/w can know
> what size DRAM is installed in each bank and 'do the right thing'
You don't need that. Its possible to figure it out in S/W.
> - a name for the %^*%(* thing, how about 'Foghorn' (after Foghorn
> Leghorn of course) If that is too Americentric, feel free to suggest
> something else. Waldorf Salad? LOAM (Linux on a MIPS)?
Good plan, but don't quit your day job.
> - for serial/parallel ports on board, how about a 16C552 - two
> 16550 uarts and a IBM compatible centronics parallel port with 8 bit
> cpu interface. Made by TI and others. Also don't forget those
> pesky line interface chips.
I still think that parallel should go on the ISA bus. I know its cheap,
but this thing is getting too expensive. As for RS-232 drivers,
Motorola 145406, has 3 transmitters and 3 receivers. You need one
> - does someone have a heat chamber to test this thing at elevated
> temperature for a while? It may be GPL h/w, but it doesn't have to
> be flaky...
My kitchen at about 3pm gets to about 110F!! :-) (The sun gets
it just the wrong way.)
> - think about cooling options for the CPU. The 33MHz 79R3051E in the MJ
> package runs pretty hot - I'm sure the 40MHz 3081E will really cook,
> especially with more cache on chip. I would plan on a heat sink and/or fan.
> Don't burn your hands :-)
My NCD-19r (with has a LSI r3k) runs warm at 33MHz; cooler than my 486.
There are temperature specs in the 3081 data sheets. We just need to
check it, as you say.
> - for debug, put some headers around the CPU for each pin. If you only
> run the local bus to the 3730 it will be hard to hook a logic analyzer to
> either the 3730 or the 3081 without using expensive test clips.
The logic analysers that I have access to come with those clips. In any
case, Waldorf want a socket next to the CPU, so this would do.
> - we should budget for appropriate filters and such for EMI. If waldorf
> wants to sell this commercially it will have to pass VDE and/or FCC
> (or CISPR) and/or other agency approvals. Does Waldorf have a
> site where they can scan the unit? Or are they going to do their own
> layout and only test their version?
Hell, I forgot about FCC. Isn't that a requirement before any sales in
the US? I've only done designs for the Australian market which doesn't
need FCC (or anything). Has someone gone though this before?
Neil Russell (The wizard from OZ)
Pyramid Technology Email: email@example.com
3860 N. First Street Voice: (408) 428-7302
San Jose, CA 95134-1702 FAX: (408) 428-8845