2708 Programming Algorithm?

From: Joe <rigdonj_at_cfl.rr.com>
Date: Mon May 6 20:06:47 2002

At 04:28 PM 5/6/02 -0600, Ben wrote:
>Richard Erlacher wrote:
>>
>> It's been a long time, but since I just recently handled the old 8748 doc that
>> has the reference I thought I saw, it'll be cleared up soon.
>>
>> I just remember that all the 87xx parts, 8741, 8755, 8748/49, etc, were all
>> 5-volt parts. further, I'm not at all sure that the 8080 had below-ground
>> signal levels, since they were intended to be attached to bipolar parts, e.g.
>> 8212, etc, which would have been intolerant of that. What I've got in my lap
>> is the 8080A data, which may, actually be different, but IIRC, the 8080 needed
>> the negative bias supply so it could swing to ground and the +12 so it could
>> swing to a reasonable high level. My only contact with the 8080 was on boards
>> made by Intel, and, while I poked around with a 'scope and other gear from
>> time to time, I don't recall ever finding an address, data, or control signal
>> that wasn't TTL compatible.

>But check the specs TTL compatible often is for 1 TTL S load for output
>lines max.

   That's not the point. The point is that the inputs and outputs are TTL (0V/5V) level and not a negative voltage. FWIW IIRC even the 8008 had a fan out of more than one. I have the manual and can look if it matters.

   Joe
Received on Mon May 06 2002 - 20:06:47 BST