[...Sorry to those who might have seen this twice. I didn't see it
come back to my site, so I'm mailing it again...]
>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.
>* CPU, peripheral controller and memory
> Allocated to: firstname.lastname@example.org
> 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
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.
>* 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.
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?
>* Ethernet port
> Allocated to: <no-one>
> 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
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