Battery warning in Falco terminals

[Brent Hilpert]

On 2018-Nov-20, at 11:18 AM, Paul Koning wrote:
>> On Nov 20, 2018, at 2:07 PM, Brent Hilpert via cctalk <cctalk at classiccmp.org> wrote:
>> 
>> ...
>> The PCB-transformer key design is novel, but (in the TS-1) so is the scanning & communication.
>> There is no microcontroller on the keyboard, scanning is performed by the main unit, it sends a key matrix address to the keyboard in serial, the keyboard sends back nothing but a binary key-pressed indication.
> 
> I'm not positive, but my impression is that the same is true for the VT-100 keyboard.


You may be right, rings a bell from working on one,
Wasn't intending to suggest the falco was necessarily unique.
IIRC, the VT-100 keyboard comm involved standard async UARTs.
It's a little weirder on the TS-1, one edge of pulses on the address-line are a clock-pulse, some uS later - determined by a monostable - the state of the same line is sampled for an address bit. After 8-10 such pulses the matrix is strobed, involving another monostable, so there are some timing issues both sides have to independently account for.