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] <mailto:[email protected]> > On Behalf Of Stephen Adolph Sent: Saturday, June 18, 2022 8:46 AM To: [email protected] <mailto:[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
