Spoken like a true software guy
Dave!
I think there are varying
interests in the group. Personally I just like
“messing with chips”, for any one of these board
there are numerous permutations and combinations as
to how they could be built. If you just want to
work with one CPU/software/application, then a SBC
is probably the way to go. The one thing the S-100
bus has going for is that it has the capability of
housing (in theory) up to 16 CPU/DMA controllers. So
if you want to have a computer that has multiple
CPU’s or develop hardware/software for one CPU using
another there is something to be said for the S-100
bus approach.
Could this be done in hardware in
other ways – absolutely. The fact that there is an
agreed upon standard and literally thousands of
S-100 boards still out there makes it easier to get
going, certainly for 8 bit CPU’s, a few 16 bit CPU’s
and now hopefully with 32 bit CPU’s.
My current system has a Z80, a
6502, an 8086, an 80386 and 68010 CPU all working
together in one box. All do (or will) share the
same hardware i.e. RAM, FDC HD controller, video,
printer etc.. BTW, we need software guys like you to
make this better!
Is there a commercial need for
this, absolutely not. Is it fun, yes (most of the
time). The future other CPU’s like the new 32 bit
Propeller (when it comes out), ARM’s, XVGA board,
SCSI etc.
That’s just me, others may
differ!
John
John Monahan Ph.D
e-mail: mon...@vitasoft.org
Text: mon...@txt.att.net
From: n8ve...@googlegroups.com
[mailto:n8vem...@googlegroups.com]
On Behalf Of yoda
Sent: Wednesday, August 14, 2013 10:09 AM
To: n8ve...@googlegroups.com
Subject: Re: [N8VEM-S100:1818] S-100 68K CPU
board V3
Hi Andrew!
I guess the real question to me
is what are we doing? Are we building / designing
hardware because we can or is there a higher
purpose. I am basically a software guy that likes
to dabble in hardware and I don't see a lot of
software being created for all these boards (maybe
the software folks are being really quiet). Like
I tell my hardware compatriots at work - you are
just building an expensive pile of sand (silicon)
without the software to be able to use it.
I think SBC is probably the
better way to go as the S100 bus is becoming a
more expensive I/O bus for these more powerful
processors and in the end limits their speed and
adds more complexity. Maybe we should explore a
better bus structure for these more powerful
processors?
Just my thoughts - would be
nice to hear what others think. No use building a
jet engine to place in a Model T Ford ?
Dave
On Wednesday, August 14, 2013 10:27:01 AM UTC-5,
lynchaj wrote:
Hi
On the S-100 80386
CPU board there is a special connector “over
the top” for memory boards with full 32 bit
addressing and 32 bit data width. The S-100
bus serves for accessing base memory and IO
mostly since it is limited to 24 bit
addressing and 16 bit data width. The S-100
80386 CPU board can work with just bus
memory but is limited to 16MB of 16 bit wide
memory and is going to be slower than with
the special memory board.
Assuming we move
forward with a more advanced 68K series
processor (68020, 68030, 68040, etc) on the
S-100 bus I recommend a similar approach if
not the same “over the top” memory boards to
make them more economical and provide a
useful amount of RAM to more powerful CPUs.
I was considering using the PAK68 approach
for a 68020 or 68030 CPU socket mezzanine
board for the S-100 68K board but in
retrospect it would probably be better to
design a new board instead.
Thanks and have a
nice day!
Andrew Lynch
Not sure it makes sense
on an S-100 board as the address space is
limited to 16 MB. It will probably be an
SBC with a couple hundred MB of memory -
when we start getting in the GB range it
is not quite as practical and the old
chips are limited to 4GB anyway without a
lot of additional memory decode tricks. I
can probably get old version of NetBSD
flavor running on even a 68K with some
tricks - at least I will be able to gauge
the complexity.
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