That's interesting. Can easily see how that would be. Now, notice that the main rom had no such function. The chip select for the main rom happens right away with no delay.
Does the rom have no time dependent power consumption? Or is the main rom just so slow? My guess is a bit of both, because T102 has a much faster main rom but the chip select circuit is the same as M100. On Monday, June 20, 2022, <[email protected]> wrote: > Thinking about this some more jogged the memory that the idea of a chip > enable came from HP first desktop scientific calculator. It was transistor > based and used so much power that the guy who invented it came up with an > enable signal for various parts of the system so everything did not need to > be powered up at one. He said HP made a lot more licensing the chip enable > patent than they ever did on calculators. > > > > Jeff Birt > > > > *From:* M100 <[email protected]> *On Behalf Of * > [email protected] > *Sent:* Monday, June 20, 2022 10:57 AM > *To:* [email protected] > *Subject:* Re: [M100] the function of A* in M100/T102 > > > > Wow, Steve what great detective work. I love thigs like this, when one > spends ages trying to figure out why something was designed a certain way > and then you have that ‘Aha!’ moment. A very good example of the art of > engineering… > > > > Jeff Birt > > > > *From:* M100 <[email protected]> *On Behalf Of *Stephen > Adolph > *Sent:* Saturday, June 18, 2022 8:46 AM > *To:* [email protected] > *Subject:* [M100] the function of A* in M100/T102 > > > > I've often wondered about the purpose of the A* signal on the M100. > > > > A* is used to control the internal RAM. It drives the timing for the RAM > chip selects. Also, since the RAM are wired with OE grounded, whenever A* > is high, the RAM will try to immediately output data, unless the processor > is writing data to it. > > > > A > > >
