I went with PLCC-44 in a couple of devices back in '81-82. The first ones I
used were the first application in which I put parts on both sides of the board.
The PLCC-68 was even more common, though many mfg's felt more comfortable with
the equivalent PGA. Most folks didn't like the relatively hot parts in a plastic
package. The 68-pin package was more common.
PLCC wasn't a "surface mount" device back in those days, being viewed as a
plastic version of PGA package. Lots of guys didn't like the gull-wing parts,
so they used the J-lead part in a socket. In most cases, the pinout of the PLCC
+ socket was the same as the equivalent PGA, if there was one.
Dick
----- Original Message -----
From: "Allison" <ajp166_at_bellatlantic.net>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, December 14, 2001 2:28 PM
Subject: Re: MITS 2SIO serial chip?
> From: Richard Erlacher <edick_at_idcomm.com>
> >
> >The 8250 was a fine chip for the application, though I wonder why they used
> the
> >DIP version. There were better choices available, but they didn't want to
> lose
>
>
> In 1981 there was only the DIP version as surface mount was not a widespread
> technology yet.
>
> >the serial port board business by putting two of them on the same card, and
> by
> >that time serial I/O chips tended to have between 2 and 8 ports on them.
>
>
> In 1981 they did exist, those with more than two ports didn't have second
> source and they werent cheap. The 8274 ( the 8088 bus version of the
> Zilog SIO) was about 4 times the cost of the 8250(in the fall of 1981)
> though it was a far better part and intel would have loved the business.
>
> What's funny is my Leading Edge Model D PC clone used 8251 and put all
> the video, floppy, printer and COM1 on the mother board. In my book the
> clones often {but, not always} improved a dumb design.
>
> Allison
>
>
Received on Fri Dec 14 2001 - 16:50:42 GMT