No, it means the output drive strength can be varied in 7 steps. Nothing to do with pull-ups or pull-downs, everything to do with EMI generation.

Yes it's pull up resistors.

Those pull up resistors are located in the processor.

The manufacture document says that those resistors are in series, but that's not logical. They must be in parallel.

https://www.pjrc.com/teensy/IMXRT1060RM_rev3.pdf
IMXRT1060RM_rev3.pdf

5–3

DSE

Drive Strength Field

Select one out of next values for pad: POR_B

000 DSE_0 — HI-Z

001 DSE_1 — Dual/Single voltage: 262/260 Ohm @ 1.8V, 247/157 Ohm @ 3.3V

010 DSE_2 — Dual/Single voltage: 134/130 Ohm @ 1.8V, 126/78 Ohm @ 3.3V

011 DSE_3 — Dual/Single voltage: 88/88 Ohm @ 1.8V, 84/53 Ohm @ 3.3V

100 DSE_4 — Dual/Single voltage: 62/65 Ohm @ 1.8V, 57/39 Ohm @ 3.3V

101 DSE_5 — Dual/Single voltage: 51/52 Ohm @ 1.8V, 47/32 Ohm @ 3.3V

110 DSE_6 — Dual/Single voltage: 43/43 Ohm @ 1.8V, 40/26 Ohm @ 3.3V

111 DSE_7 — Dual/Single voltage: 37/37 Ohm @ 1.8V, 34/23 Ohm @ 3.3V

So contrary to instructions, it seems to be 3 resistors in parallel being turned on, or off. (inst says series)

1.8v

62 ohms, 134 ohms, 262 ohms

001 = 262 Ohm

010 = 134 Ohm

011 = 88 Ohm

100 = 62 Ohm

101 = 50 Ohm

110 = 42 Ohm

111 = 37 Ohm

3.3v

57 ohms, 126 ohms, 247 ohms

001 = 247 Ohm

010 = 126 Ohm

011 = 83 Ohm

100 = 57 Ohm

101 = 46 Ohm

110 = 39 Ohm

111 = 34 Ohm

Teensy 4.1 uses:

MIMXRT1062DVJ6B

chip

https://www.mouser.com/datasheet/2/302/IMXRT1060CEC-1396580.pdf
22 k ohms, 47 k ohms, 100 k ohms

001 = 100 K Ohm

010 = 47 K Ohm

011 = 32 K Ohm

100 = 22 K Ohm

101 = 18 K Ohm

110 = 15 K Ohm

111 = 13 K Ohm