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On Sun, 16 Aug 2009 09:16:51 +0100, Orchid XP v8 <voi### [at] dev null> wrote:
>OOC, exactly how much space do you recon it would take to build 64KB out
>of discrete NAND gates?
For memory you could use a D type flip-flop which can be made using 4 NAND gates
and an inverting gate. It would be better to use a Master-slave D type flip-flop
which would double the components. So for each *bit* of memory you would need 2
X 7400s and 1/3 X 7404. or a 7474 or a 7479.
What size of word are you thinking of? IIRC the typical power consumption of TTL
is about 250 ma. You will need a robust power supply.
--
Regards
Stephen
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>> OOC, exactly how much space do you recon it would take to build 64KB out
>> of discrete NAND gates?
>
> For memory you could use a D type flip-flop which can be made using 4 NAND gates
> and an inverting gate. It would be better to use a Master-slave D type flip-flop
> which would double the components. So for each *bit* of memory you would need 2
> X 7400s and 1/3 X 7404. or a 7474 or a 7479.
>
> What size of word are you thinking of? IIRC the typical power consumption of TTL
> is about 250 ma. You will need a robust power supply.
Of course, I have no serious *intention* of making more than about a
dozen bytes of RAM using only NAND gates. ;-) But I'm aware that way
back in prehistoric times, they used to do it this way.
No wonder computers cost more that housing estates - they were *bigger*
than housing estates! :-D
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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triple_r wrote:
> a computer that gets upset when you make programming errors! There must be
> room for an "In Soviet Russia..." joke somewhere around here.
In Soviet Russia, the computer hacks you.
> - Ricky
-Aero
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On Sun, 16 Aug 2009 14:09:32 +0100, Orchid XP v8 <voi### [at] devnull> wrote:
>
>Of course, I have no serious *intention* of making more than about a
>dozen bytes of RAM using only NAND gates. ;-)
Surprise me :D
> But I'm aware that way back in prehistoric times, they used to do it this way.
>
Back in prehistoric days, at least when I started working in computing, RAM was
ferrite-core memory. Literally ferrite or ceramic toroids threaded with wires to
store information via the polarity of the magnetic fields.
http://en.wikipedia.org/wiki/Core_memory
>No wonder computers cost more that housing estates - they were *bigger*
>than housing estates! :-D
It was the air conditioning that took up the room :)
--
Regards
Stephen
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On 16-8-2009 15:09, Orchid XP v8 wrote:
>>> OOC, exactly how much space do you recon it would take to build 64KB
>>> out of discrete NAND gates?
>>
>> For memory you could use a D type flip-flop which can be made using 4
>> NAND gates
>> and an inverting gate. It would be better to use a Master-slave D type
>> flip-flop
>> which would double the components. So for each *bit* of memory you
>> would need 2
>> X 7400s and 1/3 X 7404. or a 7474 or a 7479.
>>
>> What size of word are you thinking of?
let's assume 8 bit and that we need about as much logic to select the
bits. That'll be a breadboard if about 25 by 25 meter (modulo arithmetic
errors), so not too bad.
> IIRC the typical power
>> consumption of TTL
>> is about 250 ma. You will need a robust power supply.
Cooling was a more difficult problem than the logical design of
supercomputers.
> Of course, I have no serious *intention* of making more than about a
> dozen bytes of RAM using only NAND gates. ;-) But I'm aware that way
> back in prehistoric times, they used to do it this way.
I don't think they did it with 7400s. The description of the ENIAC
suggests that they did something similar, though I would not be
surprised if they used a slightly different design. By that time the
tubes were much more versatile than simple transistors.
A popular one afrom the beginning of mainframe computers was core memory
(see e.g. http://www.columbia.edu/acis/history/core.html).
> No wonder computers cost more that housing estates - they were *bigger*
> than housing estates! :-D
That was only in a very short period of time. Aside the analog computers
then were just as big.
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On Sun, 16 Aug 2009 16:55:46 +0200, andrel <a_l### [at] hotmailcom> wrote:
>A popular one afrom the beginning of mainframe computers was core memory
>(see e.g. http://www.columbia.edu/acis/history/core.html).
Just wandering down memory lane I looked up the Honeywell H316 as it was the
first computer that I worked on. At one time marketed as "The Honeywell Kitchen
Computer" LOL http://en.wikipedia.org/wiki/Honeywell_316
http://www.bitsavers.org/pdf/honeywell/series16/h316/70130072179A_RealTimeClk_May69.pdf
I found a site with lots of documents even circuit diagrams
http://www.bitsavers.org/pdf/honeywell/series16/h316/
36 Meg pdf
http://www.bitsavers.org/pdf/honeywell/series16/h316/70130072166AV_316_ModulesAndParts_Nov74.pdf
Bookmark 2-07 gives the "Principles of Magnetic Core Operation"
--
Regards
Stephen
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Orchid XP v8 schrieb:
> It appears I had the right pins, they're just not numbered in the order
> I was expecting.
That /might/ lead to incorrectly wired circuitry :-P
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>> It appears I had the right pins, they're just not numbered in the
>> order I was expecting.
>
> That /might/ lead to incorrectly wired circuitry :-P
The point being, it *is* the two corner pins, as I expected. It's just
that those corners aren't numbered 1 and 14 for some reason.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Since I'm currently using the onboard video adapter (Radeon 3200, they
call it), I wasn't expecting to play many games until I bought a new
video card.
However, I'm quite impressed by the performance of it. Company of
Heroes runs fine (with options turned down, of course ;) ), and HL2 ran
well enough that I decided to get Ep 1&2 (they're on sale, and I've
never gotten around to playing them).
Ooh... I should install Civ IV again! That should run just fine :)
(As if I needed more ways to waste my time ;) )
...Chambers
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Orchid XP v8 schrieb:
> The point being, it *is* the two corner pins, as I expected. It's just
> that those corners aren't numbered 1 and 14 for some reason.
You're talking about the power pins?
They are typically found at the opposite corners of the chip, "bottom
left" being GND and "top right" being VCC. Not only for 74xx, but for a
great number of stuff commonly found in DIL packages (memory ICs,
microcontrollers and what-have-you-nots).
The numbering seems to have evolved independently from this, following a
"U" shape starting at "top left". This is /always/ the case for DIL
packages (with problems arising only if pins are completely left out; I
think they're counted as if they were there).
Indeed this, combined, is not very intuitive.
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