16 Nov
2005
16 Nov
'05
11:54 a.m.
Rumor has it that Ethan Dicks may have mentioned these words:
I've been thinking about the tiny-8008 project for
some time - I may
have to scrape together the parts and give it a go - I can always
borrow an 8008 from my pile of 11/34 spare parts.
I've been thinking of building my own 6809 project (I have four AVR
projects and a couple serial ports on a Linksys router I need to build
first, tho)...[1]
Originally I was going to design and build my own buss structure /
backplane ( I was thinking 80 pins - 40-pin IDE headers are bog-easy to
find... ;-) something that could expand to a 16-bit CPU....
First card would be a fully buffered CPU, next card might be 256K or 512K
RAM, 3rd card might be a small LED/LCD display (2x40 or somesuch) and of
course, one card full'o'blinkinlights... ;-)
My question: Would I be better to do that, or should I center it around an
existing buss, like VME or somesuch?
Of course, as soon as I do that, I'll have to rig
something up for a
4004... ;-) I think it wouldn't be too hard to make a 4004-based
digital clock, at least in terms of the programming.
I've been wanting to build a digital thermostat. "Why spend $50 on one from
the local hardware store, when I can build one for $100!" ;-) Naw, besides,
the prebuilt thingies don't give enough 'programmability' for my tastes.
Having started out with the 6809, personally I find it hard to get excited
about 4-bit CPUs, myself... ;-)
[[ Altho I did have at one time that Radio Shack single-TI-chip-4-bit
computer trainer thingy... ]]
Ah well, back to work.
Laterz,
Roger "Merch" Merchberger
[1] I just got the latest (non-CVS) tarball of PCB compiled on my new Linux
From Scratch 6.1 install on my laptop - I'm ready to start designing things.
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
16 Nov
16 Nov
10:12 a.m.
I've been thinking of building my own>
6809 project (I have four AVR
projects and a couple serial ports on a Linksys router I need to build
first, tho)...[1]
Just to let you know about it - you might want to check into my CUBIX
project. CUBIX is the homegrown operating system that I originally developed
for my 6809 Portable machine. It is easily portable, comes up on
minimal hardware, and gives you over 100 system calls, and a number of
applications including several text editors, assembler, debugger, APL
interpreter, 8080 simulator, lots of utlities and plenty more.
The original machine it was developed for was a homegrown portable
with 6809E CPU, 6845 video controller, parallel keyboard, couple of
6551 uarts and a 765 diskette controller. Details and photos of this
machine (and the mainboard) are on my site. I've also built the system
as a bus oriented device, and had PCBs made for the main boards
(great lab/prototyping system).
This is one of the easiest ways to get a fullly functional 6809 system
up and running. You can build a CUBIX system on quite a small card,
using just a handful of chips. All you really need is the 6809 CPU, some
RAM, 8K ROM**, serial port (I like the 6551 for it's built in baud rate
generator), and a diskette controller (I usually use a 765). I've wirewrapped
systems in just a couple of hours, and I know sevral others who have done
it as well.
Since the enture CUBIX OS fits in the 8K boot rom, RAM requirements
are very low - Also, the internal commands include FORMAT and DOWNLOAD,
which lets you format a diskette and download the applications and utilities
to it (very easy to bootstrap).
There's a 6809 simulator that run CUBIX on my site if you would like to
check it out. Also some sample schematics, as well as full source code
and documentation for the OS and all related applications/utilities.
Regards,
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
12:18 p.m.
New subject: homebrew 'puter project
Roger Merchberger wrote:
I've been thinking of building my own 6809 project (I have four AVR
projects and a couple serial ports on a Linksys router I need to build
first, tho)...[1]
You may be better off splitting it into two cards -- cpu and memory and
console.
A second board for I/O and a optional third for blinking lights. Don't
forget Henk has a 6809
cpu that has great blinking lights. It emulates a pdp 8.
http://www.pdp-11.nl/
12:22 p.m.
On 11/16/2005 at 11:54 AM Roger Merchberger wrote:
Originally I was going to design and build my own buss
structure /
backplane ( I was thinking 80 pins - 40-pin IDE headers are bog-easy to
find... ;-) something that could expand to a 16-bit CPU....
First card would be a fully buffered CPU, next card might be 256K or 512K
RAM, 3rd card might be a small LED/LCD display (2x40 or somesuch) and of
course, one card full'o'blinkinlights... ;-)
Why have a backplane at all? That much RAM is what, one or maybe two
chips?
Better than a backplane/bus, why not just a good I/O connection? A nice
serial hookup maybe?
More than fast enough for blinking lights and LCD displays. Why burden the
CPU-to-memory datapath with yucky bus interface hardware?
Cheers,
Chuck
12:56 p.m.
Rumor has it that Chuck Guzis may have mentioned these words:
On 11/16/2005 at 11:54 AM Roger Merchberger wrote:
How else could you pull a 6809 card, stick in a 68K card, and still use the
same RAM / keyboard / etc.? Or pull out one ROM card (say, running OS-9)
and put in another, running something else. ;-)
Originally I was going to design and build my own
buss structure /
backplane ( I was thinking 80 pins - 40-pin IDE headers are bog-easy to
find... ;-) something that could expand to a 16-bit CPU....
First card would be a fully buffered CPU, next card might be 256K or 512K
RAM, 3rd card might be a small LED/LCD display (2x40 or somesuch) and of
course, one card full'o'blinkinlights... ;-)
Why have a backplane at all? That much RAM is what, one or maybe two
chips? Better than a backplane/bus, why not just a good I/O
connection? A nice
serial hookup maybe?
Expandability - I eventually want to be able to build D/A \ A/D hardware,
keybaord interface(s), dual serial interfaces, I/O ports, maybe a floppy
interface, etc... Modularity can be a wonderful thing sometimes...
I have this weird tendency to over-engineer stuff... ;-) However, that has
served me well over the years; at least I don't have to *re-do* most of the
stuff I've done.
More than fast enough for blinking lights and LCD
displays. Why burden the
CPU-to-memory datapath with yucky bus interface hardware?
Dunno enough about 68Ks (yet) but 6800/6809 CPUs only have memory-mapped
I/O, so all that's needed is to buffer the lines (unless you're feeling
particularly foolhardy, like on the CoCo) and address decoding. Not exactly
a *lot* of hardware, as it were...
Besides, a secondary reason for building this is to put it in a
plexiglas/lucite case so it'll work as a functional display piece - I've
been doing some volunteer work with the local schools about "how computers
actually work" - A single board with an AVR & a few LEDs just doesn't seem
so impressive (or fun!) ;-)
'Course, with my track record, it'll prolly not happen until I retire, but
what the heck... a guy can dream, right? ;-)
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
1:14 p.m.
On 11/16/2005 at 12:56 PM Roger Merchberger wrote:
I know I'm probably suffering from something akin to USB-itis, but even
"slow" serial busses are pretty darned fast now and I really like not
having to lots of traces for bus transceivers, etc. I'd be sore tempted to
just hang on a USB controller to whatever CPU card I was building and
forget about a backplane.
I know--it wouldn't be suitable for display in a nice lucite case with
plenty of blinking lights!
Which reminds me of something that happened within a couple of months of
getting my Altair 8800 going. I'd very carefully toggled in someone's 12K
BASIC interpreter and gotten it to run and actually execute some small
programs. Way cool, I thought. So I invited a co-worker over during the
lunch hour to see what I'd accomplished.
His reaction was one of unabashed scorn. "THAT'S A COMPUTER?" said he.
"I THOUGHT YOU WERE WORKING ON SOMETHING MORE THAN A TOY." The words still
sting today. I imagine that if I'd had a 40hp MG set in my living room, or
a few CDC 607 tape drives he might have been more open-minded.
I suppose he had a point. What I'd spent on getting that Altair and SWTP
TV Typewriter going would have bought a big hunk of a Porsche 914 back
then.
If I were to build a system from chips today, I'd probably relegate all of
my I/O devices to some commodity interface, using single-chip
microcontrollers where some particular intelligence was required. Leave
the CPU free for the heavy computational lifting.
Cheers,
Chuck
Why have a backplane at all? That much RAM is
what, one or maybe two
chips?
How else could you pull a 6809 card, stick in a 68K card, and still use
the
same RAM / keyboard / etc.? Or pull out one ROM card (say, running OS-9)
and put in another, running something else. ;-)
1:18 p.m.
New subject: homebrew 'puter project
Roger Merchberger wrote:
s it were...
Besides, a secondary reason for building this is to put it in a
plexiglas/lucite case so it'll work as a functional display piece -
I've been doing some volunteer work with the local schools about "how
computers actually work" - A single board with an AVR & a few LEDs
just doesn't seem so impressive (or fun!) ;-)
Well how do they work ... :) I think a simple cpu design that is
flowcharted with multi-colored leds
( say red for 1's green for 0's ) where the data walks from gate to
gate in the alu.
Say 32 words of memory for program memory ( loaded from rom ), and 16
words of ram,
and few hands on I/O devices for the people using the project.
1:35 p.m.
--- Roger Merchberger <zmerch at 30below.com> wrote:
Expandability - I eventually want to be able to
build D/A \ A/D hardware,
keybaord interface(s), dual serial interfaces, I/O
ports, maybe a floppy
interface, etc... Modularity can be a wonderful
thing sometimes...
That's nice but there is one problem....
'Course, with my track record, it'll prolly
not
happen until I retire
yep that's the problem!
A point design is a joy to design and build, quick and
much cheaper too
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2:31 p.m.
On 11/17/05, Roger Merchberger <zmerch at 30below.com> wrote:
Dunno enough about 68Ks (yet) but 6800/6809 CPUs only
have memory-mapped
I/O, so all that's needed is to buffer the lines (unless you're feeling
particularly foolhardy, like on the CoCo) and address decoding. Not exactly
a *lot* of hardware, as it were...
The 68000 is like the 6800/6809 in that regard... no special I/O bus
or instrunctions,
just memory decoding, and a lot of MOVE instructions,
-ethan
6824
days inactive
6824
days old
8 comments
6 participants
participants (6)
-
bfranchuk＠jetnet.ab.ca -
cclist＠sydex.com -
dave04a＠dunfield.com -
ethan.dicks＠gmail.com -
gkicomputers＠yahoo.com -
zmerch＠30below.com