‫Hello and welcome, guys.
‫We need to enable the a line before we continue or we could run into problems.
‫So essentially, if we don't enable a 20 line, we won't have access to the 21st bit of any memory access.
‫So any memory address.
‫And this could obviously cause problems for us.
‫So buying it by enabling the AT&T line, we ensure that that bit is accessible.
‫So once again, I'm Osterberg here, that a 20 line article is a very useful resource.
‫We just scroll down, we can see that there's a fast 828 new system, starting with the IBM who has
‫a fast a twenty option that can quickly enable that a 20 line.
‫So this is quite easy to do.
‫We read from the port zero ninety two, then we set a bit in the register and write the register back
‫out.
‫So just in case you haven't seen these instructions before, the end instruction reads from the processor
‫bus and the instruction writes to the processor bus.
‫And obviously we use the bus to communicate with hardware connected to the motherboard.
‫OK, this chip set with the fast say twenty option.
‫They obviously have a part that's listening for 069, too, OK, so we can read and write to that.
‫OK, so we go to a visual studio code then and I'm going to copy this and we're going to put that aside
‫and we're going to do this in 32 bit mode.
‫So in our low 32 label, just after we set up all of the registers, we're just going to paste that
‫in.
‫Or you can ride it whatever's best enable that a 20 line case.
‫Let's just test everything we're going to go make.
‫We're going to go keep in GDB target remote kumu system.
‫Dasch 686 underscores 64 dash FDA to force pain dash s capital s.
‫Dash GDB studio, OK, and now we're going to do to continue, we're going to press Chelsea.
‫And we can see that it's running on our jump, so this a 20 lines all fine.
‫Now we've we've told it that we want to enable the line.
‫As long as it supports the fast 20, it will now be set up correctly.