Re: [9fans] /sys/include/ip.h 5c(1) - LONG POST

[W B Hacker <wbh@conducive.org>]

Ethan Grammatikidis wrote:
> On Sat, 10 Oct 2009 04:15:59 +0800
> W B Hacker <wbh@conducive.org> wrote:
>
>> The only 'glue' needed was level-shifters - discrete transistors on my OSI
>> Challenger II, Motorola 1488 & 1489 diode-coupled-logic on everything up until
>> the 16XXX derivative of the 8250 was sucked into a 'bridge' chipset.
>>
>
> I remember being quite surprised by the first UARTs which had level
> shifters on the chip, and they came out around 1993 or so didn't they?
> As far as I know it was hardly possible to handle RS-232's 25V signals
> on the same die as logic functions back in the 80s.

It wasn't 'hard' - especially since the 25V, though more common then than now -
was more likely to be between 7 to 15 volt, and 5V would usually get the job done...

But it just wasn't smart.

The separate circuitry - or even its PC board traces - all too often had to act
as a fuse - protecting the more expensive part of the kit with a cheap and easy
to replace module.

>
>
>> PCDOS was lousy at I/O, and Windows no better.
>
> Linux either. Makes me sad. ;-J
>
>

Don't be too harsh. All Linux lacks is a decent kernel.

;-)

Bill