CBM's Plans for the RISC-Chipset By: Dave Haynie
Reproduced from an 1995 issue of Amiga Report.
#33630 comp.sys.amiga.misc 8k
From: email@example.com (Dave Haynie)
Subject: Re: CBM4s Plans for the RISC-Chipset
Date: Tue, 24 Jan 1995 23:21:15 GMT
Organization: Scala Inc., US Research & Development
>Just found this article in c.s.a.advocacy and thought it would
someone here too.
>Following the original article : ...
>Here are the highlights of an interview of Chris Ludwig, an
>CBM's engineering staff, at the World of Amiga exposition,
>the french mag "Amiga News" January 1995.
>AN: Who decided the choice of the CPU [HP-PA]: the
>CL: It was CBM's decision. We spent a lot of time choosing the
>CPU for our needs. Our decision was based on these factors:
>compatibilty with existing HP products because they've
>Apollo (graphic stations manufactured) and compatibilty with
>(there is a 68000 emulation mode in the PA-RISC).
Wrong. The HP-PA was chosen for use in The RISC Project
based on the needs of that project. HP-PA code is reasonably
dense for a
RISC processor, the instruction set is easily extensible, the core
enough to sit on a chip occupied by other functional units
copper, system control), etc. There is no "68000 emulation
PA-RISC, the Apollos Commodore had were 680x0 based and not an
>AN: Is this emulation hardware ?
>CL: Both. In a lot of cases, the instructions' architecture
>similar to the 68000 and there are also software emulation
>so that makes the porting easier.
HP-PA offers the same feature that makes porting from 680x0 to
PowerPC easier -- big endian word ordering. That's it.
We had some
concern and the early stages of a future plan for use of the Hombre
in high-end Amigas (based on my "Acutiator" system architecture),
would initially be as a graphics card, not a host CPU. The
for Hombre would be a next-generation CD32 replacement with no
>AN: So it will be quite easy to create a portable AmigaDOS
Nope. Lots of the AmigaOS was in assembly, and would have
to be rewritten.
There's a good chance data alignment issues would be an additional
even on C code, though Apple solved some of this by building in
compiler options for alignment control.
>It was one of the main reasons for the choice of HP's
Not even in the top 10 as far as the reasons for the choice.
>CL: We already got software emulation of the four parts of
>they are working well so we're quite happy.
>AN: Will these four chips be a single chip later ?
The design called for two chips. The PA-RISC core,
blitter, copper, etc.
live in a "system control" chip, roughly analogous to
at least in a rough sense. The other was the actual video
the same basic idea as Denise/Lisa/Monica. Neither design was
more work was done on the former, but it's a much larger
chip. And there
was basically one guy working on it, Ed Hepler. Tim MacDonald
designer) worked on the display chip for awhile, before he left C=
to work on display chips for Compaq.
>CL: Of course, it will, but we don't need extraordinary
backup, at least
>not much more than what we needed in the past. We can
certainly do it
>in 18 months with reasonable backup.
The initial schedule of 18 months was for the Hombre game
There's no real OS here, just a library of routines, including a
package, which would probably be licensed. The Amiga OS was
not to have
run on this system in any form. An AmigaOS port to RISC for
machines was something those of us in the high-end group were
favor of, but it was not at the time under consideration by
course, at that time, Commodore was going down fast, so there no
any of that stuff.
>AN: Windows NT will running on it.
>CL: Yes, Windows NT works on PA-RISC and we won't do anything
>it (WinNT) from working on our system.
Supposedly an NT port is underway for PA-RISC, but not yet
at that, there's no reference platform for building binary
systems. Clearly this could be solved by the HAL (Hardware
Layer) that NT talks to on all machines, kind of a higher-level
despite the clear logic of that approach, the short sighted weenies
seem to control the system architectures (if you can call them
that) of the
Next Generation Personal Computers don't seem to have advanced much
the 1970s when it comes to these areas. Look no further than
nonsense for a good example; Apple and IBM have spent years arguing
hardware trivialities that shouldn't be anything a "shinkwrapped
ever have to be directly concerned about. Maybe NT did
better, but maybe
Even if you had NT, what would you really have? My guess
is a slower way
to run Windows 3.1 programs than you current get on cheap
NT applications are rare. Native NT applications that support
Alpha platforms, which have been shipping for quite some time, are
still. Rarer even still are applications compiled for
PowerPC, since only
Motorola is pushing that. Microsoft could have gone to a
distribution format, but again, why do something the right way,
users benefit. And they're not to be trusted.
>It will be a system running three OS (including HP's own
We never intended to run HP-UX, and at least at the time, HP was
nervous about direct competition (which is why the PA-RISC isn't
off the shelf like SPARC, MIPS, PowerPC, etc.). It would have
impossible to legally run it.
>AN: Mr Amor of CEI told on Portal last day that he wasn't
quite sure on
>the choice of the RISC chip. He said Macs and PCs are
heading to the
That's a valid concern for "computer-level" machines, such as
people think of as a RISC-Amiga (eg, any RISC machine running a
of the AmigaOS). It's a non-issue with games machines, there
machines out there with compatible CPUs, and the CPU is the least
worries, since every graphics subsystems is even more different
another than the host CPU. Again, PA-RISC was the choice of
for the Hombre chipset and probably a games machine or low-cost,
performance smart 3D graphics subsystem (Hombre will be both if
>[...] In short: It's important for them to have a cheap
>for multimedia stuff, video games ... Some of the old
>be present and new ones should be impressive
Hombre doesn't support any of the existing modes. It does
support 16 and
24-bit true color displays, I don't know if there's a LUT mode or
main emphasis is on 16-bit direct color. You could have four
playfields active at once, and there were blitter mathematics
like in AAA, only better) that could operate very efficiently on
>heard and seen from Sega's Saturn specs, it should not even
come close to
>the new Amiga Chipset specs,
Strictly speaking, Hombre is not an Amiga chip set. While
it supports some
of the Amiga ideas, it's no more Amiga compatible than an SVGA chip
actually, since all SVGA chips support planar as well as chunky
at least up to 4 bits/pixel). This shouldn't be a big deal
planned Retargetable Graphics system for AmigaOS 4.0 was to support
pixels, though much more work was needed for that, especially to
direct mapped color.
ex-Commodore Engineering | See my first film
Sr. Systems Engineer | Class of
'94 | "The Deathbed
Scala Inc., US R&D | C= Failure n. See: Greed
"Caught a bolt of lightning, cursed the day he let it go"
...And, Mr. Haynie's response to my request for reprint
#20 jcompton 4k
Subject: Reprint right request, sir.
Date: Wed, 25 Jan 95 11:17:52 EST
Yeah, sure. I guess you should mention that in both cases,
we're acting on
whatever information we have on the Hombre project. This was
hush-hush, not only because it was The Secret Project, but since Ed
was for the first two years or so the only guy working on it, he
necessarily have lots of design review meetings. My only
involvement with the project was simply ensuring Ed knew about
requirements for Hombre to be used as a PCI card, which was in the
last I saw them. I certainly haven't seen anything about the
June, but I do know what was said about it last Spring. The
work at the time was Dr. Alan Havemose's investigation of 3D
plans were underway for any kind of AmigaOS port at the time.
Many issues hadn't been resolved by the time I left. It
was assumed that
most of the "generic peripheral" type things would hang off the PCI
though few should be necessary for a games machine. They
hadn't decided on
the audio subsystem; there was at one time talk about adopting the
channel subsystem from Mary (AAA), but there was also talk about
off-the-shelf sound chip or cheap DSP.
Should Hombre ever see the light of day, there's certainly the
that more traditional Amiga features could be incorporated,
AAA is not also resurrected (keep in mind that during most of the
the Hombre project, it was assumed that AAA would exist and it
much too expensive for games machines or very low end personal
It's possible that a port of the Amiga OS could be done, but it
lots of work, even if they could get together enough Amiga
get the thing going intelligently. And of course the
has been around for awhile. A 680x0 is not that hard to
especially since applications under the AmigaOS run in user mode,
supervisor instructions (all the MMU codes, for instance) need be
And emulation should be much faster than under the Mac, since
are all indirected jumps, not A-line traps.