Digital or Analog Autobrakes
The 100 series and most (not all) 200 series B737 had analog auto brakes which worked slightly differently to the later model B737 digital autobrake system. The analog would apply a fixed brake pressure on wheel spin up then reduce or increase braking once the decel rate was calculated, hence the increase wear seen with the early intoduction on the B737. The initial brake application was always rather severe which made many pilots distrustful of the autobrakes.