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Invisible wrote:
> - Board B has less writing printed on it between the two RAM chips. The
> actual components mounted there appear identical, but just fewer markings.
Wrong. Actually there are slightly more components on board A and C (the
"rev:3" boards).
BTW, what *are* those absurdly tiny 2-pin devices scattered all over the
board? Resisters? Many of them have labels printed on the board such as
"R7". But a few are labelled "C13" or similar...
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> BTW, what *are* those absurdly tiny 2-pin devices scattered all over the
> board? Resisters? Many of them have labels printed on the board such as
> "R7". But a few are labelled "C13" or similar...
Yes, take a wild guess what R and C stand for :-)
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Invisible <voi### [at] dev null> wrote:
> BTW, what *are* those absurdly tiny 2-pin devices scattered all over the
> board?
Wouldn't you be referring to surface-mount resistors?
--
- Warp
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scott wrote:
>> BTW, what *are* those absurdly tiny 2-pin devices scattered all over
>> the board? Resisters? Many of them have labels printed on the board
>> such as "R7". But a few are labelled "C13" or similar...
>
> Yes, take a wild guess what R and C stand for :-)
I was under the impression that capacitors have to be of a specific
physical size in order to have the correct capacitance...
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Invisible <voi### [at] devnull> wrote:
> I was under the impression that capacitors have to be of a specific
> physical size in order to have the correct capacitance...
It's all about total surface area. If you pack tons of really thin
surfaces really close to each other in a layered fashion, you can get
a surprisingly large surface area inside a surprisingly small volume.
--
- Warp
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On 22-4-2009 12:56, Invisible wrote:
> scott wrote:
>>> BTW, what *are* those absurdly tiny 2-pin devices scattered all over
>>> the board? Resisters? Many of them have labels printed on the board
>>> such as "R7". But a few are labelled "C13" or similar...
>>
>> Yes, take a wild guess what R and C stand for :-)
>
> I was under the impression that capacitors have to be of a specific
> physical size in order to have the correct capacitance...
depends on what the correct capacitance is. On a board that runs at a
high frequency I expect some very tiny ones.
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On 22-4-2009 13:05, Warp wrote:
> Invisible <voi### [at] devnull> wrote:
>> I was under the impression that capacitors have to be of a specific
>> physical size in order to have the correct capacitance...
>
> It's all about total surface area.
and the width and composition of the insulator layers.
> If you pack tons of really thin
> surfaces really close to each other in a layered fashion, you can get
> a surprisingly large surface area inside a surprisingly small volume.
>
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> I was under the impression that capacitors have to be of a specific
> physical size in order to have the correct capacitance...
Within reason, yes. I suspect they can manufacture a range of values for
each package size.
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Le 22.04.2009 12:37, Invisible nous fit lire :
> The Holtek chips say "HT27C512-70" followed by a number that's unique to
> each chip. Apparently this part number is a "OTP CMOS 64K x 8-Bit EPROM".
>
> http://pdf1.alldatasheet.com/datasheet-pdf/view/64437/HOLTEK/HT27C512.html
>
> "The HT27C512 chip family is a low-power, 512K bit, +5V electrically
> one-time programmable (OTP) read-only memories (EPROM)."
>
> Um, wouldn't that make it a PROM rather than an EPROM? The E is for
> *erasible*. :-P
it is erasable.
E from EPROM is erasable programmable (EP).
first E from EEPROM is electrically.
EPROM are erased with UV-light. EEPROM are erased electrically.
Now, if the packaging has no window (cheaper), the EPROM become a OTP EPROM...
a PROM is using fuse, so technically they are different.
But at the core, it's still an EPROM... that packaging does not allow to erase.
(how do you like your marketing text ?)
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scott wrote:
>> I was under the impression that capacitors have to be of a specific
>> physical size in order to have the correct capacitance...
>
> Within reason, yes. I suspect they can manufacture a range of values for
> each package size.
Mmm, OK.
So my next question is... why does a digital device require so many
millions of resisters and capacitors?
(Maybe millions is an exaggeration, but there sure is a lot of them
here... Big ones, tiny ones... I assume the tiny ones *must* be mounted
by machine?)
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