12 Dec
2005
12 Dec
'05
8:28 a.m.
woodelf wrote:
Dave Dunfield wrote:
Consider memory mapping, e.g. with the already somewhere mentioned
74ls610/611/612/613. At least the 612 is still
available from unicornelectronics. Using memory pages is not worse than
x86 segments. With some external
memory (74F189) it should also fit into a 9572.
(The debug enhancements are brought to you
courtesy of the stack
corruption bug :-).
and the number 6809 ...
Looking at his home page you got alot more stuff about old machines
including a few 8's 11's and 12's.
I think cubix was a good idea, but this 15 years too late for me as I
realize in hindsight that 128k of
memory - split code and data is needed for any real work. This the
crummy 8088 has but not the 6809. Part of the reason I building a 9/18 bit cpu ( If I
can ever keep the
same instruction set or bit with --
next week it could be 12/24 bits using 2901 bit slices rather than the
CPLD's I have ) is that I have
256k of memory something that I feel is right for a 'small'
computer. With the CPLD's I can run @
What is *right* or *wrong* with a small computer? I think we are
meanwhile somewhat "damaged" from the
wealth of CPU and memory resources from even mediocre PCs. Small systems
are attractive IMHO because
they are still manageable by a single person to be designed and built up
from the ground. For daily work I use
PCs or Macs
or alike, but the small system is fun and hobby. I'll never
load a modern MS-Word file into such
a system, therefore even 256k would be too small. My diploma thesis in
the eighties was typesetted on a C64.
Generations of adults played with toy trains; the relation to small but
handcrafted computers is quite close.
1.25 MHZ and get the feel for home-brew other than the
PC or COCO-3
options I had at the time.
I did have a COCO-3 but I never did get memory or OS9-II and a HD to
upgrade it to a real machine.
A new design will probably contain a compact flash or SD card for
external storage; far more space available
than required to store all available software for such systems. I have
no scruples to deviate from the rules of purity
(thou shalt not use modern parts in old computers) there. I'm after all
hobbyist, not curator.
Holger