11 Nov
2005
11 Nov
'05
7:33 p.m.
Subject: Re: FPGA VAX update, now DIY TTL computers
From: woodelf <bfranchuk at jetnet.ab.ca>
Date: Fri, 11 Nov 2005 16:14:58 -0700
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>
Chuck Guzis wrote:
74LS10 dip .25 at ea .17 at Q25 |74F10 dip .19 at ea .14 at Q25 |74HCT10 dip .25 at ea .18
at Q25
JDRmicrodevices.com
Even at a buck a chip if your only using 36 of them thats not painful.
Allison
Consider the very old Packard Bell PB250--22 bit
words, fewer than 400
transistors and 2500 diodes, 63 instructions. Power consumption about 40
watts, exclusive of I/O:
The trick, of course, is to use bit-serial methods. It seems to me that
one could greatly simplify construction of a homebrew machine that way.
We're not doing this for speed, right?
Not really that much, it is registers that hog all the logic gates.
I guess you would save only about 1/3 of your logic gates.
Cheers,
Chuck
I got playing around with 74xx logic and the best I can do for my CPU design
is about 36 chips for a two bit slice. Now who sells 3-input NAND's
and Gated
J/K F/F's cheap like they did in the 70's? And lots and lots of 14
pin Sockets!
12 Nov
12 Nov
1:12 a.m.
Allison wrote:
74LS10 dip .25 at ea .17 at Q25 |74F10 dip .19 at ea
.14 at Q25 |74HCT10 dip .25 at ea .18 at Q25
JDRmicrodevices
I plan to get then from unicorn electronics, about the same pricing.
Even at a buck a chip if your only using 36 of them
thats not painful.
The quick logic alu design is about 20 TTL per bit and
I am planning 18 bits wide... say 50 ents each for a 74XX gate that
is $10 per bit.
Rounding that to 20 bits that is $200 for the logic. Good sockets are
$.50 so
about $200. Not knowing PCB layout say a square inch per chip ... 20
sq inches
@ 75 cents a inch ... $300 for the PCB's ... That is where my money
is going.
OH well I have all next year for that project, but I have two goals
for the ALU
and Control so I can have feel for what the 60's Computers were like
size wise.
1) 14 pin DIPS. 2) 7400 logic.
Allison
I can get a 200 watt PC power supply ... 5 volts @ 20 amps that I
hope is
ample ...
PS. As for getting 7400 off scrap boards, if I had the scrap boards I
would
most likely try to get the scrap item working again. :D
2:06 a.m.
On 11/11/2005 at 11:12 PM woodelf wrote:
PS. As for getting 7400 off scrap boards, if I had
the scrap boards I
would most likely try to get the scrap item working again. :D
There are plenty of junk boards that have no particular useful function.
I've got a bunch of ISA cards that I salvaged. All were old models of a
gizmo that appeared to a PC as a monochrome adapter, but which translated
the CPU writes to video memory to serial codes to a VT-220 type terminal.
Why would anyone want to do this? Dunno--it wasn't fast and all of these
boards lack the PROMs that would make them work in any case. But they've
got lots of LSTTL, some 4x16K DRAMs and a Z80A, Z80 CTC and a Z80 DART, all
in sockets. Perfect scrap items.
Cheers,
Chuck
4:38 a.m.
There are plenty of junk boards that have no
particular useful
function.
Doubtless true, but...
I've got a bunch of ISA cards that I salvaged.
All were old models
of a gizmo that appeared to a PC as a monochrome adapter, but which
translated the CPU writes to video memory to serial codes to a VT-220
type terminal.
...this does *not* qualify! Argh!
Why would anyone want to do this?
So you can take a peecee with a BIOS not supporting serial console and
hook it up to a multi-serial-port gadget for remote console access, of
course.
I believe there's a company making those gadgets right now (PC Weasel,
I think they call it - it took a while before I twigged to the
difference between that and the kind of weasel used to read "odd" disks
- catweasel, I think it's called). That they have a market indicates
that this is not "no particular useful function", even today.
Dunno--it wasn't fast and all of these boards lack
the PROMs that
would make them work in any case.
Well, I suppose what's done is done. But taking a board that needs
nothing but a PROM to be a highly useful gadget and blowtorching it to
turn it into a pile of spare parts is the sort of thing that makes me
wince when I hear of it, akin to that time I mentioned I was looking
for the SBus card part of an xbox (the Sun SBus extender, not the game
console) and someone said something like "oh dear, just two weeks ago I
acrapped a dozen of them".
/~\ The ASCII der Mouse
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11:55 a.m.
On 11/12/2005 at 4:38 AM der Mouse wrote:
...this does *not* qualify! Argh!
So, let's look at what I have--old models (not production, but scrapped
prototypes). They didn't work very well and were never the finished
product (I've got one of those). They work only with 4.77MHz PCs and only
with VT-220 type terminals--and only in text mode. With no BIOS and no
schematics, how on earth is it useful doing anything with them other than
scrapping them? I suspect that the original producer would have scrapped
them for parts if it could have done so economically.
Worth of electronic (or any other) stuff is not intrinsic--things are worth
something only if they can meet some need--either utilitarian or emotional.
If it has no value, maybe it's best to find something that it will be good
for. I can use the chips; the solder will go into the scavenging box that
I use for brass instrument repair. Basically, the only thing left is the
old depopulated PCB and I've even cut those up to use as dividers in
storage bins.
If no one wants the Durango that I've got, I know that it's got a very
expensive 48v DC motor with precision encoder that I can use for something
else. The boards have lots of nice LSTTL and someone will doubtless be
willing to pay bucks for the 100 tpi Tandon floppy drives. The heavy gague
aluminum chassis can go to the smelter to make beer cans. The thing is
loaded with useful Torx-head screws. I've got some spare PCB's for it and
they may meet the torch very soon if I can't find a taker. The case being
HD structural foam will have to be landfill, but there are no heavy metals
there at least.
I've got two of these and don't need a second one. Why should I assume
the burden of keeping a second around? That's what's called a white
elephant.
I used to get upset when I'd find an old tuba used as a garden planter or
fountain or had holes drilled in it to hang it in a restaurant. But not
any more--the instruments were being put their best use by their owners as
they saw it. It's all just man-made stuff, after all--if the best use of a
clarinet is as a tomato stake, so much the better that it stays out of the
waste stream.
Since I'm not a collector, I view anything that I do that keeps things,
either in entirety or in pieces, out of the landfill as a worthy purpose.
It isn't as if there's nothing around that can better perform the same
function as the original. Modern PCs run faster, have better displays and
printing and lots more storage.
Cheers,
Chuck
3:49 p.m.
...this does
*not* qualify! Argh!
So, let's look at what I have--old models (not
production, but
scrapped prototypes). They didn't work very well and were never the
finished product With no BIOS and no schematics, how on earth is it
useful doing
anything with them other than scrapping them?
The same could be said of much of the hardware which is salvaged and
then made workable again. As for "how", well, schematics can be traced
from boards - I've done it in simple cases and
others here have done it
in much more complex cases - and, that aside, just because
you don't
have suitable ROMs doesn't mean nobody does. (Perhaps nobody in fact
does, and what you've now said makes that seem more plausible, but
based on what you said before, I saw no reason to think that.)
I suspect that the original producer would have
scrapped them for
parts if it could have done so economically.
Lots of hardware producers scrap things that we (FSVO "we") find
eminently worth salvaging.
I've got two of these and don't need a second
one. Why should I
assume the burden of keeping a second around? That's what's called a
white elephant.
Sure, but to dissect it for parts before even checking if anyone else
has any use for it? That's something I regularly dealers reviled for
doing.
It isn't as if there's nothing around that can
better perform the
same function as the original. Modern PCs run faster, have better
displays and printing and lots more storage.
As anyone on this list should know, performing the same function, even
if actually done (and depending bus compatability, even the modern
analog - a PC Weasel - may not perform the same function), does not
mean that nobody wants the older version.
Again, what you've now said makes that seem less likely (but still not
impossible).
/~\ The ASCII der Mouse
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5:51 p.m.
On 11/12/2005 at 3:49 PM der Mouse wrote:
Okay, I'll make a deal you can't resist. Anybody wants these things, all
they have to do is come up with a BIOS PROM for these things and pay
shipping. The manufacturer was Tripas Technologies.
Bet there are no takers. Tripas was one of those
flash-in-the-pan-horribly-underfunded Silicon Valley startups. The Valley
was full of them in the 80's. Firms like these helped keep firms like
Halted in business.
With no BIOS
and no schematics, how on earth is it useful doing
anything with them other than scrapping them?
The same could be said of much of the hardware which is salvaged and
then made workable again. As for "how", well, schematics can be traced
from boards - I've done it in simple cases and others here have done it
in much more complex cases - and, that aside, just because you don't
have suitable ROMs doesn't mean nobody does. (Perhaps nobody in fact
does, and what you've now said makes that seem more plausible, but
based on what you said before, I saw no reason to think that.) Sure, but to dissect it for parts before even checking
if anyone else
has any use for it? That's something I regularly dealers reviled for
doing.
I offered it for free, along with a 14" 40 MB HPIB hard disk that went with
it. A couple of tickles, but no serious interest. Too bad--I've got a
fairly good selection of engineering documentation as well as loads of
software for it. Revile me if you want, but I feel no moral imperative to
be a warehouse for unwanted obsolete stuff.
The trouble is that when you get down to the PC era, there were so many
brands that flickered in and out of existence that there's just no point to
accumulating a lot of stuff that pretty much all did the same thing. I can
reel off names like Preis and MAD that almost no one remembers for their
unremarkable products.
Cheers,
Chuck
10:33 p.m.
Okay, I'll make a deal you can't resist.
Anybody wants these things,
all they have to do is come up with a BIOS PROM for these things and
pay shipping. The manufacturer was Tripas Technologies.
What bus are they for? What kind of ROM socket do they have (I'm
assuming the ROM is socketed)?
Sure, but to
dissect it for parts before even checking if anyone
else has any use for it? That's something I regularly dealers
reviled for doing.
I offered it for free, along with a 14" 40 MB HPIB hard
disk that
went with it.
11 p.m.
On 11/12/2005 at 10:33 PM der Mouse wrote:
The ROM is socketed and I believe was a 27128. ISA 8-bit bus.
Cheers,
Chuck
Okay, I'll
make a deal you can't resist. Anybody wants these things,
all they have to do is come up with a BIOS PROM for these things and
pay shipping. The manufacturer was Tripas Technologies.
What bus are they for? What kind of ROM socket do they have (I'm
assuming the ROM is socketed)? 
11:03 p.m.
New subject: IBM 029 or 129
I just saw a IBM 129 keypunch go by on Ebay, so I know there's still a
few out there. :-) For sentimental reasons, I would love to add either
an 029 or 129 keypunch to my collection. Does anyone where one might be
available?
Mike Loewen mloewen at cpumagic.scol.pa.us
Old Technology http://ripsaw.cac.psu.edu/~mloewen/Oldtech/
4:33 p.m.
On 11/11/2005 at 11:12 PM woodelf wrote:
>PS. As for getting 7400 off scrap boards, if I had the scrap boards I
>would most likely try to get the scrap item working again. :D
Me too. I've got piles of obscure boards that I'd like to get going again
sometime. Most have no real practical function, but are part of the
history of computing/electronics.
About the only thing I'll raid for parts are no-name clone PC
motherboards and cards.. And those are not a good source of standard TTL,
alas.
There are plenty of junk boards that have no particular useful function.
I've got a bunch of ISA cards that I salvaged. All were old models of a
gizmo that appeared to a PC as a monochrome adapter, but which translated
the CPU writes to video memory to serial codes to a VT-220 type terminal.
Now that sounds unusual enough to be very interesting. Put it this way,
if I had something like that I'd be trying to track down a dump of that
missing ROM. I would not be raiding it for parts.
-tony
6827
days inactive
6828
days old
10 comments
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participants (6)
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ajp166＠bellatlantic.net -
ard＠p850ug1.demon.co.uk -
bfranchuk＠jetnet.ab.ca -
cclist＠sydex.com -
mloewen＠cpumagic.scol.pa.us -
mouse＠Rodents.Montreal.QC.CA