4004 and IC history / was Re: Vintage computer photogallery

[dwight elvey]

> From: hilpert at cs.ubc.ca
>
> dwight elvey wrote:
>>
>>> From: hilpert at cs.ubc.ca
>>> ---snip--->
>>> Regarding the 4040, I'm speculating as I've never dealt with one or come
>>> across the pinout, but I suspect the 4040 essentially integrated the
>>> 4004/4008/4009 into one larger package making it look more like a 'standard'
>>> microproc in terms of signals/interface (somebody correct me if I'm wrong).
>
>> No, it was just a 4004 with, as I recall, two more instructions.
>> It kept the 4004 multiplexed bus and connected to 4001's and 4002's,
>> just like the 4004.
>> As I recall, it had 4 times the address space with bank selects. I'd
>> need to look at the specs again to be sure.
>
> Thanks for the correction, but why was it in such a larger package?
> (4040 was a 28 or 40-pin package wasn't it?).

Hi

 It had more select lines for a larger address space. I think it added

an Interupt and a single step as well. I believe that made up for the

rest of the pins. It also had TTL compatible pins for many of the signal

lines. I believe that required an extra power line as well. I recall that the

reset line had inverted logic sense but that didn't effect the pin count.

 I recall that did cause problems for the UPP. The other chips still had

the original sense of logic. On the UPP, they'd used a transistor to

invert the level. The problem was that they'd released the CPU about

3 cycles befor releasing the ROM's reset.

 It was flakey on reset. Some boards just never reset right.

They even had an ap note stating to put a few nops at the start

of the ROM to fix this. This didn't always work right. Changing the

reset order fixed it.

 It seems the 4040 was a 24 pin part.

Dwight



_________________________________________________________________
Climb to the top of the charts!  Play Star Shuffle:  the word scramble challenge with star power.
http://club.live.com/star_shuffle.aspx?icid=starshuffle_wlmailtextlink_oct