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Why is AC and ACT not more widely used?

M

Michael

Jan 1, 1970
0
Hi - can anyone tell me why the AC and ACT chip families are not as widely
used as some others? They seem not to have compatibility problems, and they
have a much higher drive capability. So why are they not used more often?
Or are they already widely used, and I've just been living in a cave my
entire life? thanks,

Michael
 
J

Joseph Legris

Jan 1, 1970
0
Michael said:
Hi - can anyone tell me why the AC and ACT chip families are not as widely
used as some others? They seem not to have compatibility problems, and they
have a much higher drive capability. So why are they not used more often?
Or are they already widely used, and I've just been living in a cave my
entire life? thanks,

Michael

A few reasons (and they don't just apply to AC and ACT):

-Trend toward lower voltage, faster technologies
-Increased use of programmable logic or custom chips
-Increased use of microcontollers with only little bits of external logic

These days, about the only place you'll see boards full of MSI logic is
in old equipment where modern replacements are impractical, such as in
the space shuttle and the Canadian armed forces.
 
C

Chris Carlen

Jan 1, 1970
0
Michael said:
Hi - can anyone tell me why the AC and ACT chip families are not as widely
used as some others? They seem not to have compatibility problems, and they
have a much higher drive capability. So why are they not used more often?
Or are they already widely used, and I've just been living in a cave my
entire life? thanks,

Michael

They are discrete logic, which is not used much anymore. Most logic is
done in FPGAs or CPLDs, or ASICs. Even the "chipsets" on PC
motherboards are ASICs of sorts. Note the progression from the IBM PC
which was basically a 3 dimensional rectangular prism packed with
discrete logic chips, to the modern PC motherboard. How many discrete
logic packages can you count there? Sometimes none!

Most discrete logic families are trimming down to nothing more than bus
buffer, receiver/driver, and level shifting functions. And since much
of the core logic (CPUs, ASICs, FPGAs) are running at lower voltages
than 5V, there are a bunch of lower voltage logic families that have
sprung into being.

5V logic is fading away, and discrete 5V logic is almost gone. About
all I use it for is learning about logic. Almost anything I could want
to design can be done now with two chips: a CPU and a PLD, or perhaps
one or two specialized communication or data conversion devices, or
memories.

But I use a lot of HC, HCT, and sometimes AC and ACT for input and
output buffering between logic stuff and the outside world.

Good day!

--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected] -- NOTE: Remove "BOGUS" from email address to reply.
 
G

Genome

Jan 1, 1970
0
Joseph Legris said:
A few reasons (and they don't just apply to AC and ACT):

-Trend toward lower voltage, faster technologies
-Increased use of programmable logic or custom chips
-Increased use of microcontollers with only little bits of external logic

These days, about the only place you'll see boards full of MSI logic is
in old equipment where modern replacements are impractical, such as in
the space shuttle and the Canadian armed forces.

You might wish to replace impractical with critical. One old thing I heard
is that the space shuttle runs off old pieces of shit for a simple
reason..... New pieces of shit are shit.

Something I wrote a long while back, and I'll try to recreate it, you might
like to edit it, I'm sure the wonders of modern news messages will render it
toilet. I know I did this before the thing blew up the first time so any
reference is purely unintended.

"Columbus, this is Houston, you are go for main computer start sequence."

'Beep'

"Houston, this is Columbus, initiating main computer start sequence now."

'Beep'

'Currlick'

Whirr Whirr Whirr, Chirp Chirp Chirp... Beep, Somebodies BIOS, Checking
Memory, 640K base, click, 384K extended, click, 1024K, click 2048K

Memory Check complete.

"Columbus, this is Houston, main engine start in 10 seconds"

DOS is now checking your memory....

click 64K
click 128K
snore

"Columbus, this is Houston, main engine start in 5 seconds"

Memory check complete.

Mode CON, something or another, select codepage, something else.
Mode Something, something or another, something else.
Keybd, tra... laa...laa
Mousdrv, tra... laa..laa
Path = huge path plus other things.
Load something.
Load something else.
Set something to something

"Columbus, this is Houston, main engine start in 2 seconds"

Himem is now testing your extended memory.

click 64K
click 128K
snore

"Columbus, this is Houston, main engines are now Go"

Windows 3.11 is now loading.

'Oh, **** ****, c'mon c'mon.'

"Columbus, this is Houston, release in,

5
4
3
2
1

"Columbus has left the tower, Whoooooo Whooooo Whooooo!!!!!"

'Shit, Shitttt, click on that one. Arghhh, double click on it. Yes!!
Yess!!!'

Rotate_shuttle_ right.exe has caused a general protection fault in

Lots of hex numbers Here
And Even More Here
With some more Here
And some other such stuff

Contact the supplier of this software for an explanation. Ha Ha.





If you credit the Canadians with the same sense as NASA then you need to
live in fear, or was that a warning?
 
T

The Raymond Family

Jan 1, 1970
0
Primarily because of power consumption, as well as the trend to lover
voltage families. Its not an issue of SSI vs LSI since you asked about those
families specifically. The days of designing several amp power supplies for
simple logic or buffering are long gone.

Dana
 
J

Joseph Legris

Jan 1, 1970
0
Genome said:
You might wish to replace impractical with critical. One old thing I heard
is that the space shuttle runs off old pieces of shit for a simple
reason..... New pieces of shit are shit.

Something I wrote a long while back, and I'll try to recreate it, you might
like to edit it, I'm sure the wonders of modern news messages will render it
toilet. I know I did this before the thing blew up the first time so any
reference is purely unintended.

"Columbus, this is Houston, you are go for main computer start sequence."

'Beep'

"Houston, this is Columbus, initiating main computer start sequence now."

'Beep'

'Currlick'

Whirr Whirr Whirr, Chirp Chirp Chirp... Beep, Somebodies BIOS, Checking
Memory, 640K base, click, 384K extended, click, 1024K, click 2048K

Memory Check complete.

"Columbus, this is Houston, main engine start in 10 seconds"

DOS is now checking your memory....

click 64K
click 128K
snore

"Columbus, this is Houston, main engine start in 5 seconds"

Memory check complete.

Mode CON, something or another, select codepage, something else.
Mode Something, something or another, something else.
Keybd, tra... laa...laa
Mousdrv, tra... laa..laa
Path = huge path plus other things.
Load something.
Load something else.
Set something to something

"Columbus, this is Houston, main engine start in 2 seconds"

Himem is now testing your extended memory.

click 64K
click 128K
snore

"Columbus, this is Houston, main engines are now Go"

Windows 3.11 is now loading.

'Oh, **** ****, c'mon c'mon.'

"Columbus, this is Houston, release in,

5
4
3
2
1

"Columbus has left the tower, Whoooooo Whooooo Whooooo!!!!!"

'Shit, Shitttt, click on that one. Arghhh, double click on it. Yes!!
Yess!!!'

Rotate_shuttle_ right.exe has caused a general protection fault in

Lots of hex numbers Here
And Even More Here
With some more Here
And some other such stuff

Contact the supplier of this software for an explanation. Ha Ha.
If you credit the Canadians with the same sense as NASA then you need to
live in fear, or was that a warning?

Same result, different reasons. NASA has all the cash in the world, but
nobody knows how the goddamn hardware works any more. The space shuttle
might as well have been designed by Trafalmadorians. That Canadian
forces are so poorly funded cash that they have just declared a tactical
retreat from ... peacekeeping!
 
A

A E

Jan 1, 1970
0
Michael said:
Hi - can anyone tell me why the AC and ACT chip families are not as widely
used as some others? They seem not to have compatibility problems, and they
have a much higher drive capability. So why are they not used more often?
Or are they already widely used, and I've just been living in a cave my
entire life? thanks,

Michael

Last time I checked, and this was years ago so I could be very wrong, is that
this technology was ahead of its time with regards to output rise/fall times,
but was packaged in less than ideal DIPs, which increased loop inductance,
combined with poor layout on behalf of the people using these chips (I've seen
some nightmares) and poor bypassing caps (all 100n caps are the same, right? :)
) made this family hard to use for the average project. The same could be said
of the F family. I remember a system in 1986 that used one 74F74 on a PCB with
no ground plane, and the instructions were to try several F74s till you found
one that worked... Yikes.
 
C

CFoley1064

Jan 1, 1970
0
Michael said:
Last time I checked, and this was years ago so I could be very wrong, is that
this technology was ahead of its time with regards to output rise/fall times,
but was packaged in less than ideal DIPs, which increased loop inductance,
combined with poor layout on behalf of the people using these chips (I've
seen
some nightmares) and poor bypassing caps (all 100n caps are the same, right?
:)
) made this family hard to use for the average project. The same could be
said
of the F family. I remember a system in 1986 that used one 74F74 on a PCB
with
no ground plane, and the instructions were to try several F74s till you found
one that worked... Yikes.

A. E. speaks truth -- comparatively difficult to control
overshoot/undershoot/ringing issues. Later chips had controlled rise/fall
times, which pretty much solved the problem, but by that time, the parade had
moved to lower voltages and programmable chips, with all the connections
internal to the IC. The story of Engineering -- once you really know how to do
something, it's obsolete. But, as R. A. Heinlein once remarked, that's a good
thing, because otherwise we'd still be climbing in trees.
 
M

Mike Harrison

Jan 1, 1970
0
Hi - can anyone tell me why the AC and ACT chip families are not as widely
used as some others? They seem not to have compatibility problems, and they
have a much higher drive capability. So why are they not used more often?
Or are they already widely used, and I've just been living in a cave my
entire life? thanks,

Michael
I'd say mainly because their high speed is often not necessary in the sort of designs that use
descrete logic - and most high-speed designs these days are done in FPGAs etc.
 
C

Chris Carlen

Jan 1, 1970
0
Genome said:
"Columbus, this is Houston, main engines are now Go"

Windows 3.11 is now loading.

'Oh, **** ****, c'mon c'mon.'

"Columbus, this is Houston, release in,

5
4
3
2
1

"Columbus has left the tower, Whoooooo Whooooo Whooooo!!!!!"

'Shit, Shitttt, click on that one. Arghhh, double click on it. Yes!!
Yess!!!'

Rotate_shuttle_ right.exe has caused a general protection fault in

Lots of hex numbers Here
And Even More Here
With some more Here
And some other such stuff

Contact the supplier of this software for an explanation. Ha Ha.


What's really scary is the use of Windows on military platforms such as
aircraft carriers, etc.

I think it should be banned from all government use.


Good day!


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected] -- NOTE: Remove "BOGUS" from email address to reply.
 
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