dsr=deasserted, ddsr=no_change, teri=no_change, dcd=deasserted, dcts=no_change, ddcd=no_change, cts=deasserted, ri=deasserted
UART Modem Status Register
| dcts | Delta Clear to Send 0 (no_change): undefined 1 (change): undefined |
| ddsr | Delta Data Set Ready 0 (no_change): undefined 1 (change): undefined |
| teri | Trailing Edge Ring Indicator 0 (no_change): undefined 1 (change): undefined |
| ddcd | Delta Data Carrier Detect 0 (no_change): undefined 1 (change): undefined |
| cts | Line State of Clear To Send 0 (deasserted): undefined 1 (asserted): undefined |
| dsr | Line State of Data Set Ready 0 (deasserted): undefined 1 (asserted): undefined |
| ri | Line State of Ring Indicator 0 (deasserted): undefined 1 (asserted): undefined |
| dcd | Line State of Data Carrier Detect 0 (deasserted): undefined 1 (asserted): undefined |