gauging interest in VAX 6000-530

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Tue Oct 26 20:53:11 1999

> I would suspect that it was not intended to be tied
> directly to a bus. One would normally have some robust
> receiver that would invert the signal. In the days when
> it was designed, the 0 to 2.5V TTL bus was just starting
> out. Many had other voltage ranges and required some
> conditioning. The simplest conditioning circuits usually
> had an inverted signal out.
> Dwight

Ah, not even close. TTL voltages on busses were old hat by then. The
intent was to NOT connect 8259 inputs directly on busses as they are MOS
devices and susceptable to damage. The expectation was at minimum an
inverter ahead of the input.

Also, many of the intel devices had interrupt pins that went active high.

That or maybe they ran out of room on the die for an inverter.

Allison
Received on Tue Oct 26 1999 - 20:53:11 BST