12f629 vs ATtiny 11L

[Bruce]

@ DEVICE MCLR_OFF, INTRC_OSC, WDT_OFF, BOD_ON, PWRT_ON, PROTECT_OFF

DEFINE OSCCAL_1K 1 ' calibrate internal osc

CMCON = 7
GPIO = 0
TRISIO = 0

Main:
    GPIO.0 = 1  ; 1uS ON
    @ GOTO $+1  ; 2uS ||
    @ GOTO $+1  ; 2uS ||
    @ GOTO $+1  ; 2uS ||
    GPIO.0 = 0  ; 1uS OFF
    GOTO Main   ; 2uS || (10uS total)

That should give you around 100kHz with 7uS ON with 3uS OFF.