brew-your-own-unibus boards?

From: Michael Sokolov <msokolov_at_ivan.Harhan.ORG>
Date: Tue Jan 20 13:29:42 2004

Ethan Dicks <dickset_at_amanda.spole.gov> wrote:

> Yes, but some devices are not so old and _do_ use ASICs. There are some
> peripherals that came out at the same time as the 11/20 (~1970) that
> they are made up of several square feet of TTL/Linear chips.

Well, what I meant was that UNIBUS and Q-bus were designed to be implementable
without ASICS using only discrete logic, and the simpler devices were
implemented that way.

> Unibus? 8640, 8641, 340, 8881, DC013 (custom DEC chip)
> Qbus? DC003, DC004, DC005, DC006, DC010, 74LS240, 8837, 8838
>
> In other words, with few exceptions, *not* ordinary TTL chips (though ISTR
> one of their busses used hand-selected 7438s chosen for low (1uA?) leakage.

Hmm, 74LS240 for Q-bus? It's just a standard three-state TTL inverting buffer,
isn't it? For driver, receiver, or both?

> designed-as-such bus drivers/receivers from companies like
> National Semiconductor.

Does NS still make them?

MS
Received on Tue Jan 20 2004 - 13:29:42 GMT