MITS 2SIO serial chip?

From: Peter C. Wallace <pcw_at_mesanet.com>
Date: Fri Dec 14 15:19:20 2001

On Fri, 14 Dec 2001, Richard Erlacher wrote:

> Horsefeathers! The reason they did all the stupid stuff they (IBM) did was
> because INTEL told them to, since there was nobody on the PC team smart enough
> to design a microcomputer, yet dumb enough to risk doing it in their (IBM's)
> corporate environment. ISTR that the original cause for the presence of the
> 8255 was the need for it in the parallel port (see the comments in the original
> BIOS listings in the tech ref).

Fishfeathers! I stand by my original post. whether Intel helped create the
mess or not is immaterial...


> The 8250 was a fine chip for the application, though I wonder why they used the
> DIP version.

What other 8250 option than 40 pin DIP was available in 1981?


  There were better choices available, but they didn't want to lose
> 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.

Nonsense, What 8 port chips were available in 1981? Were there even any
2 port chips for the Intel bus?

>
> Dick
>
> ----- Original Message -----
> From: "Peter C. Wallace" <pcw_at_mesanet.com>
> To: <classiccmp_at_classiccmp.org>
> Sent: Friday, December 14, 2001 12:28 PM
> Subject: Re: MITS 2SIO serial chip?
>
>
> > On Fri, 14 Dec 2001, Gene Buckle wrote:
> >
> > > > NS* did use them as did many others. The worst chip was
> > > > the 8250.
> > >
> > > Which makes me wonder what possessed IBM to pick it for the PC.
> > >
> > > g.
> >
> > The same reason they chose active high edge triggered interrupts on the
> > bus (wrong on both counts)
> >
> > The same reason they used 8 bits of an 8255 to read the KB shift register
> > that had a (unused) tri-state
> >
> > The PC = A horrible, amateurishly designed kluge
> >
> >
> > Peter Wallace
> >
> >
>
>

Peter Wallace
Mesa Electronics
Received on Fri Dec 14 2001 - 15:19:20 GMT