On Apr 22, 23:01, Tony Duell wrote:
> > I thought of that too. Then you might be able to do it with an AOI
package,
>
> Oh, AOIs are fun, but not general enough for this...
You tend to need more than one small package to anything very useful
> > but I'd use a 156, which is a demultiplexer/decoder but with open-collector
> > outputs, which I'd wire-AND.
>
> Good guess. What you need is a fixed AND matrix to get all the possible
> product terms and then a programmable OR matrix to combine the right ones
> to form the desired output.
>
> That's _exactly_ what a PROM is, of course.
>
> It's also what a multiplexer is.
A neat solution. Of course, anything you can do with minterms can also be done
with maxterms.
> What worries me is that the above seems not the taught any more. And
> people don't seem to have grown up fiddling with TTL chips (or
> equivalent).
Here, 1st Year CompScis do a series of practical problem exercises with TTL,
one of which ends up building a multiplexer from basic gates. The next (or
maybe next but one) involves something that's complex to do with normal minterm
techniques, and often involves using a multiplexer as a building block.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
On Apr 22, 19:12, Allison J Parent wrote:
> LSI-11/03 cpu and box. The backplane was wired for only 16bit addesses.
> Also that particular CPU put some of the microcode signals on what would
> have ben the A16-21 lines.
Nitpick: Actually, it's wired for 18-bit (it has to be, for parity), and the
extra microcode signals are only on the A18-21 lines.
You can have fun with General Robotics backplanes/PSUs. Some of these put 24V
AC on the lines normaly used for A20 and A21.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
But, since Alphas must share SOMETHING in common with the PDP-11,
wouldn't it be possible to write a normal program for the Alpha,
running under NT or Linux, that would give PDP emulation at P-II-like
performance? Of course, I'm assuming that some of the PDP instructions
can go unchanged directly into the Alpha. Also, I would guess that a
G3 with an emulator could outperform the slower pentiums. But, then
again, why not emulate a Whirlwind or a Mark I for the same? It would
be much easier. I don't really see how an emulated PDP-11 outper-
forming a pentium would mean anything at all.
Now, making a VAX that would do that is a bit more interesting, though
probably already done. VAX is much more useful these days than PDP-11.
More on this subject: I have long thought that some computers that
are now mostly PD, like the C-64, should be rebuilt in kit form and
sold to kids for $20 each. Now THAT would be nice. Oh, and make them
make their own kernel, and hold a contest for the best one. The
winner gets an emulated PDP-11.
I really must stop eating sugar as well.
>incremented value) and three for JSR I Z 10 (fetch 10, write
incremented
>value, stash return address at location pointed to by incremented
value),
>so I could be wrong) each of which depend on the previous one. You're
not
>going to get hot performance out of that unless you decide that the
main
>memory can be built using a 5-port register file on the chip.
>
>I've occasionally wondered about doing a tight hand-coded PDP-11
emulator that
>fits in the primary cache of an Alpha. If possible, you'd be using the
Alpha
>essentially as a programmable microengine and programming it to be
PDP-11.
>The reason to fit it in the primary cache is because of how the Alpha
boots;
>at reset, it loads its primary cache from an external serial ROM and
begins
>executing it. If you could fit the emulator in the primary cache, you
could
>think of the Alpha+SROM as a PDP-11 microprocessor.
>
>Roger Ivie
>ivie(a)cc.usu.edu
>
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What would happen if we made a PC-sized PDP-11 processor using the Alpha
technology? (On a single chip, clock it at ~300-400 MHz)
As the PDP-11 instruction set is MUCH better than 80x86, would it outrun
a PC? Could this be a Pentium Killer?
-------
<>As the PDP-11 instruction set is MUCH better than 80x86, would it
<outrun
<>a PC? Could this be a Pentium Killer?
as it was in 1982-3 the PCversion of the PDP-11 aka PRO350 could eat
the XT and turbo XT for a snack. When the AT came around DEC popped
out the pro380 with the J-11 cpu...gulp, burp! ATs are tasty.
Competing against the mostly 16bit 8088/6 and the 286 the PDP11 was out
front. To match a 16bit cpu against a 32bitter... you must be inhaling!
Allison
After your done laughing remember this...
At the time the VAX was new in the market the PDP-11 group took most of
their standard 11/70 peices and cooked up the 11/74 which was a 4cpu SMP
11/70 and could eat vaxen(11/780) for snacks. That was it's demise...
there were only four working 11/74s built before that was crushed.
<Hmm, refresh my memory, now what were the PDP-11 instructions to
<directly address 4GB of memory? I can't seem to recall any 32 bit
<address registers.
Look in the VAX archectecture book.
<Darn. I've really lost it...how did the virtual memory hardware work in
<a PDP-11?
Nicely (again the vax is a mostly stretched 11).
<Seriously, if you mean the sorta RISC like instruction set in the 11 is
RISC?????? PDP-11 is the most CISC machine in the 16bit realm. What
other 16bitter is a two address orthoginal machine?
<better than the x86 set, then DEC probably would have come up with
<something like that. Course, with extra silicon, they could have gone
<to 64 bits, and put more cache onboard, then clock it really fast. Then
<come up with some catchy marketing name, like Gamma, or Beta, or ....
They did called it VAX and when it came time to outvax VAX then comes
alpha.
Allison
<Um... Am I way out here? Doesn't the 23 support 22 bit addressing? And
The basic M8186 early revs are 18bit but most work as 22bit, the later
revs were 22bit. That's assuming the backplane is wired for 22bit as
well.
<I never before heard of a 16 bit Qbus! ISTRT the F11 processor is
LSI-11/03 cpu and box. The backplane was wired for only 16bit addesses.
Also that particular CPU put some of the microcode signals on what would
have ben the A16-21 lines.
<settable between 18 and 22 bit (128KW, 256KB and 2MW, 4MB respectively).
<The 18 bit setting is used in the 23 on 18 bit Qbuses and in the 24 on
<unibuses. The 22 bit setting is used on 22 bit Qbuses, but you need
<extra hardware to use it in the 24 (i.e. on unibus).
Your thinking of latter machines with specific backplanes.
Allison
> What would happen if we made a PC-sized PDP-11 processor using the Alpha
> technology? (On a single chip, clock it at ~300-400 MHz)
> As the PDP-11 instruction set is MUCH better than 80x86, would it outrun
> a PC? Could this be a Pentium Killer?
I doubt it could be a Pentium killer, but I could be wrong. The RISC
machines get performance by making it difficult to go to memory; on the
PDP-11, it's much to easy to go to memory.
Take, for example, the PDP-8. The worst-case instruction on the PDP-8
could require as many as five memory accesses (hmm; I forget which one
took five. I only count four for ISZ I Z 10 (fetch 10, write incremented
value, fetch from incremented value, write incremented value pointed to by
incremented value) and three for JSR I Z 10 (fetch 10, write incremented
value, stash return address at location pointed to by incremented value),
so I could be wrong) each of which depend on the previous one. You're not
going to get hot performance out of that unless you decide that the main
memory can be built using a 5-port register file on the chip.
I've occasionally wondered about doing a tight hand-coded PDP-11 emulator that
fits in the primary cache of an Alpha. If possible, you'd be using the Alpha
essentially as a programmable microengine and programming it to be PDP-11.
The reason to fit it in the primary cache is because of how the Alpha boots;
at reset, it loads its primary cache from an external serial ROM and begins
executing it. If you could fit the emulator in the primary cache, you could
think of the Alpha+SROM as a PDP-11 microprocessor.
Roger Ivie
ivie(a)cc.usu.edu
Seth and Pete were discussing the PDP11-23...
>> 2) Same as above, but for the M8044-DB boards. I could put one
>> of these in with the M8047's to get a full 64Kword of RAM, yes?
>> Does anyone know what the DIP-switch settings for these boards
>> are?
>
> Yes, but I'm not sure why you say "full" and 64Kword" together :-)
> 32KW (64KB) is the limit for 16-bit addressing, or 128KW (256KB) for 18-bit
> addressing. Ignoring the I/O page, that is.
Um... Am I way out here? Doesn't the 23 support 22 bit addressing? And
I never before heard of a 16 bit Qbus! ISTRT the F11 processor is
settable between 18 and 22 bit (128KW, 256KB and 2MW, 4MB respectively).
The 18 bit setting is used in the 23 on 18 bit Qbuses and in the 24 on
unibuses. The 22 bit setting is used on 22 bit Qbuses, but you need
extra hardware to use it in the 24 (i.e. on unibus).
Just my half groat's worth.
Philip.
On Apr 22, 1:57, Tony Duell wrote:
> Jack Peacock wrote:
> > 'No, I can do it with a normal 16 pin TTL chip that doesn't have to go
> > in a programmer first'. So, what was the chip ?
> >
> > 74LS138, 1 of 8 decoder, the three inputs go to A, B, C, all 8
> > possibilities decoded on the outputs.
>
> Alas not.. I didn't want the 8 separate combinations of the 3 input
> variables - I wanted a single output that was a complex function of them
> - something like A.C + A.B/ + A/.C/.B or something...
I thought of that too. Then you might be able to do it with an AOI package,
but I'd use a 156, which is a demultiplexer/decoder but with open-collector
outputs, which I'd wire-AND.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
Sure. And then Apple would show our mascot, Barney, in flames.
I like this already!
>
>What would happen if we made a PC-sized PDP-11 processor using the
Alpha
>technology? (On a single chip, clock it at ~300-400 MHz)
>As the PDP-11 instruction set is MUCH better than 80x86, would it
outrun
>a PC? Could this be a Pentium Killer?
>-------
>
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<are there any good sites out there containing collections of schematics
<for old machines? I occasionally come across sites with a few schematics
No.
<interest in this? I was thinking more along the lines of some of the
<more obscure hardware out there though, as there's probably plenty of
<places to get details on common machines such as the popular 8-bit
<micros of the early 80's. Would be nice to have copies of ROM/Disk
<images where possible too...)
There is the problem of copyrights and permission. Not as easy as you'd
think as the copyright live past the companies demise so you have to
track where or who still holds it.
Allison
As the PDP-11 instruction set is MUCH better than 80x86, would it outrun
a PC?
-------
Hmm, refresh my memory, now what were the PDP-11 instructions to
directly address 4GB of memory? I can't seem to recall any 32 bit
address registers.
Darn. I've really lost it...how did the virtual memory hardware work in
a PDP-11?
Seriously, if you mean the sorta RISC like instruction set in the 11 is
better than the x86 set, then DEC probably would have come up with
something like that. Course, with extra silicon, they could have gone
to 64 bits, and put more cache onboard, then clock it really fast. Then
come up with some catchy marketing name, like Gamma, or Beta, or ....
Jack Peacock
I have C-64 ones. You could attach a gender changer to the koala
pad if it has an Apple plug, and use it on a Commodore.
>Does anyone have the disks for the paint program that came with the
Apple
>Koala pad?
>
>Thanks
>
>manney(a)lrbcg.com
>
>
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<PROM, or maybe one of those TI PALs with the 74-series numbers'. I said
<'No, I can do it with a normal 16 pin TTL chip that doesn't have to go
<in
<a programmer first'. So, what was the chip ?
<
<74LS138, 1 of 8 decoder, the three inputs go to A, B, C, all 8
<possibilities decoded on the outputs.
< Jack Peacock
How about 74153 or 74155 real handy for creating complex miniterms that
a small prom or pal might be used for.
Allison
<> =============================================================guide rai
<> +
<> +
<> +
<> +
<> +++++++++++++++++++++++++++ <<<<<<<direction of motion (96 needed)
<> ^ +
<> | +
<> / +
<> | +
<> |=============================================================guide rai
<> ^optos to read the leading edge of the card for column clock, spacing
<> is such that each one is obscured as the column is over the column
<> leds making it self indexing. It's possible to go very fast.
<
<Now that I like!. I wonder where I can find some cheap photodiodes.
<
<What about one of the CCD (or similar) linear image sensor chips? They're
<quite cheap in surplus shops now, I think... A bit of optics to focus the
<image onto the sensor, and a bit of electronics to drive it (which is not
<that hard to design).
CCD needs a fair amount of electronics, photo transistors are cheaper and
simpler. Jade, JAMCO, JDR and BG micro list phototransistors pretty
cheap.
Allison
>(Cautiously, looking around). Is all the nastiness over, now?
Been over for weeks. It seemed to merely be 'growing pains.'
>Does anyone have the disks for the paint program that came with the Apple
>Koala pad?
I remember hearing that it should work with any app that supports mice.
Glad to have you back. (I was wondering where the heck you were.)
Tim D. Hotze
(Cautiously, looking around). Is all the nastiness over, now?
Does anyone have the disks for the paint program that came with the Apple
Koala pad?
Thanks
manney(a)lrbcg.com
> > panel monitor used an octal keypad & display, and the octal thinking
carried
> > over to the assembler package. Heath also used "split octal" in the
fashion
> >
> Actually I think Octal is a dumb idea for 8 or 16 bit processors :-) -
A side note...on the IMSAI front panel the address/data switches came in
two colors, red and blue, so you could group them for hex or octal
inputs. (Obscure trivia, the prototype IMSAI used black switches.) You
could tell just by looking at someone's front panel if they preferred
hex or octal. Mine is in hex, S/360 Assembler was the first assembly
language I learned, and it was in hex.
If I recall correctly, Microsoft was an early user of split octal. Soon
after the 4K/8K BASIC, MS came up with an editor/debugger package for
Assembler that used the split octal notation (fuzzy here, does anyone
else remember that package, it was short-lived).
Octal proved useful in suprising ways. On Seymour Cray's CDC 6000
series, with a 60 bit word, you might think that a dump using 15 hex
digits per word would be the most useful, but in fact that was never
done, because the 60 bit word was broken down into 15 and 30 bit
instructions (multiple instructions per word, a Cray innovation I
believe), easy to see in octal but not a good fit in hex. Plus, the
character set normally used was 6 bit, not 7 or 8 bit ANSI.
Jack Peacock
-Matt Pritchard
Graphics Engine and Optimization Specialist
MS Age of Empires & Age of Empires ][
> -----Original Message-----
> From: Jeff Kaneko [SMTP:Jeff.Kaneko@ifrsys.com]
> Sent: Wednesday, April 22, 1998 9:37 AM
> To: Discussion re-collecting of classic computers
> Subject: RE: The PC's Soviet?
>
>
> >
> > There were all kinds of small Apple cloners around, with various
> Apple
> > variety and fruit names ("Granny Smith", "McIntosh", "Pear", etc.).
> The
> > only obvious differences between most of these machines and an
> actual
> > Apple ][+ was the lack of the Apple logo, and usually the presence
> of
> > lower case display (though not necessarily the shift-key mod, which
> my
> > machine lacks). Some had additional stuff, though, like function
> keys and
> > slightly differently shaped cases. Or maybe a different colour of
> > plastic.
>
> I fondly remember an issue of BYTE from long ago, that was the April
> 1st edition, that had a phoney advertisement in it for a 'Lemon
> Computer' that looked suspiciously like an Apple ][ (with a rather
> distressed and dissheveled user scratching his head . .).
>
> Wasn't that Creative Computing?. Back in the late 70's they would do
> an "April fools" section of their magazine. One year they printed it
> upside down at the back of the magazine so if you flipped it over, it
> looked like a different magazine.
Have you considered doing this for acoustic delay lines?
Actually, I was thinking about making an emulator that would use
.WAV files instead of .T64 or whatever.
>too. However, I could generalize and say they were all DOS-based,
>written in Pascal or assembler, don't come with source code, have
>poor documentation, etc. and I want to roll my own in straight portable
C.
>I'd rather make it general to handle old S-100 tapes, C-64 tapes, etc.
>instead of just hard-coding one flavor. It should be ready in
>the year 2010.
>
Don't bet on it. I have a book that predicted quality software by
1990. Seriously, though, I don't think collectors are in danger of
making their hobby worthless by saving too much. I doubt you will see
an "extra" C-64 in 2010. They will all be in the hands of collectors
or landfills.
>rescue old data. Sure, QuickCams are nearly disposable now. Cheap
>$1,500 PCs include them these days. Five years from now, they'll be
>embedded in cheap monitors. Ten years from now, they'll be in cereal
>boxes. Unless the hobby of collecting computer junk is adopted by
>Hollywood stars, I humbly suggest that it will be at least *more
difficult*
>for you to find spares for your original equipment than it will be
>for me to find something that could deliver a bitmap by looking
>at my punched card. :-)
>
>- John
>Jefferson Computer Museum <http://www.threedee.com/jcm>
>
>
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>> If not the schematics themselves, then how about a database indicating who
>> has what? Users could submit a list of what they have, and others could
>> search it for needed contacts.
That's a pretty good idea... maybe store machines, related hardware,
whether the user has manuals for the machine or not, other notes etc...
It's a shame though about the copyright situation; I try to store binary
images of everything that I can in the hope that I can recreate boot
disks etc. in the event of problems, but it would be nice to be able to
share those freely with others...
(I suppose the danger with this, as with anything on the 'net, is that
we end up with thousands of people all trying to do the same thing and
end up with the current situation of knowing that the information is
probably there *somewhere* but spending years finding it...)
cheers
Jules
>
On Apr 22, 16:08, Philip.Belben(a)powertech.co.uk wrote:
> Subject: Re[2]: PDP 11/23 help needed
> Seth and Pete were discussing the PDP11-23...
> ISTRT the F11 processor is settable between 18 and 22 bit
I forgot -- there's a bit in SSR3 that sets 18/22. You're quite correct about
that.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
On Apr 22, 16:08, Philip.Belben(a)powertech.co.uk wrote:
> Subject: Re[2]: PDP 11/23 help needed
> Seth and Pete were discussing the PDP11-23...
>
> >> 2) Same as above, but for the M8044-DB boards. I could put one
> >> of these in with the M8047's to get a full 64Kword of RAM, yes?
> >> Does anyone know what the DIP-switch settings for these boards
> >> are?
> >
> > Yes, but I'm not sure why you say "full" and 64Kword" together :-)
> > 32KW (64KB) is the limit for 16-bit addressing, or 128KW (256KB) for 18-bit
> > addressing. Ignoring the I/O page, that is.
>
> Um... Am I way out here? Doesn't the 23 support 22 bit addressing? And
> I never before heard of a 16 bit Qbus! ISTRT the F11 processor is
> settable between 18 and 22 bit (128KW, 256KB and 2MW, 4MB respectively).
> The 18 bit setting is used in the 23 on 18 bit Qbuses and in the 24 on
> unibuses. The 22 bit setting is used on 22 bit Qbuses, but you need
> extra hardware to use it in the 24 (i.e. on unibus).
An 11/23 only supports 18/22-bit addressing if it has the MMU chip fitted,
which
almost all do, though it was, strictly speaking, an option (at least, for most
of the 23's life).
Early KDF11-A's (Rev.A) only support 18-bit, most (Rev.C) support 22-bit
addressing -- iff they have the MMU. Otherwise, they can only access 16-bits
of
address space. I don't recall any setting to change that, you just only get 18
bits in an 18-bit backplane. If you try to access beyond that range, you get a
bus error. ISTR that the ODT still works (always 18-bit) without the MMU,
though. I can't easily check as the only one I have running ATM is a 22-bit
system.
A number of KDF11-A's were fitted to 11/03's as upgrades, and those had 18-bit
backplanes. The 11/03, however, only had a 16-bit address range, as did early
core, MOS RAM, and ROM boards. I wasn't referring to the bus as 16-bit, but to
the address range.
For slightly different reasons, you can't use an MSV11-D (or several other
options) in a 22-bit system. It will fit in the backplane, and work fine, but
it effectively turns the whole system into 18-bit, because it doesn't decode
BAL18-21, and therefore responds to sixteen blocks of addresses.
For similar reasons, the RKV11-D is not often used in 18-bit or 22-bit systems,
since it can only perform DMA with 16-bit addressing (you can access the
registers in an 18- or 22-bit system, of course, because it responds to the
BBS7 signal). There are lots of other I/O options with similar restrictions.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
Hi all,
are there any good sites out there containing collections of schematics
for old machines? I occasionally come across sites with a few schematics
/ info for specific machines, but has anyone collected stuff together
for several different machines into one place?
(It's something I keep on meaning to do myself - would there be much
interest in this? I was thinking more along the lines of some of the
more obscure hardware out there though, as there's probably plenty of
places to get details on common machines such as the popular 8-bit
micros of the early 80's. Would be nice to have copies of ROM/Disk
images where possible too...)
cheers
Jules
