11 Jun
2006
11 Jun
'06
4:17 a.m.
Chuck Guzis wrote:
There was (and maybe still is) a valid use for
sockets.
The "was" was when LSI IC prices were high. There was just too much
invested in them to scrap them along with a defective board. This still
obtains with CPUs and memory in PCs. At one time, two-channel serial I/O
boards for PCs were shipped with one 8250 and one set of 1488/89s. The
positions for the second port were socketed. Before that, almost any LSI
IC was socketed, such were the economic realities.
The "is" is when a ROM needs to be socketed for the purpose of a field
upgrade, although flash is making this pretty much obsolete.
I can't think of any other reasons. Are there any?
In a "PC", <shrug>
In a CNC machine that has 240V running around next to signal
lines from LVDT's etc. where there is a real risk that
"something" can end up where it shouldn't be (e.g., 240V
shorting to the LVDT inputs and taking out the front end
on the interface) you might think twice! A socket is real
cheap insurance.
Some products aren't suited to use of FLASH (e.g., gaming devices
tend to want *real* ROMs so they can't be tampered with unless
seals are physically disturbed). Older products couldn't
bear the cost of *big* FLASH devices.
Some products may be designed *knowing* that a device is not
yet available for production -- yet you don't want to delay
your product's market entry. So, you might opt to install
a socket that can support this "enhancement" in the future
without requiring user's to send their devices in for
service.
Some options are just too expensive to build in to each
product (e.g., coprocessors)
I see sockets being around for a very long time, yet!