All of those simplifications are great to see! 😃L has one more unique feature: even though it is implemented in hardware as (and can be written to as) a 16-bit register, it behaves as a 15-bit register when reading data out onto the write lines. Bit 15 of L can never make it out onto the write lines; instead, bit 16 of L is placed onto both WL15 and WL16. The AGC software sometimes uses this feature for overflow correction, since writing something into L and then reading it back out will effectively copy the upper sign bit into the low one. From software's perspective, I don't _think_ there is any way to test the value of bit 15 of L once it's been written to. Sometimes more software-focused documentation will call L a 15-bit register because of that -- but the hardware makes extensive use of bit 15 of L for multiplication and division, so that's not really fully true. Everything that needs the true value of the bit can still access it through your L15 pin.
I thought I had noticed something along those lines. Thanks for pointing it out. I see L15 is used in certain cases of the WYD pulse and some of the ZIP logic
All of those simplifications are great to see! 😃L has one more unique feature: even though it is implemented in hardware as (and can be written to as) a 16-bit register, it behaves as a 15-bit register when reading data out onto the write lines. Bit 15 of L can never make it out onto the write lines; instead, bit 16 of L is placed onto both WL15 and WL16. The AGC software sometimes uses this feature for overflow correction, since writing something into L and then reading it back out will effectively copy the upper sign bit into the low one. From software's perspective, I don't _think_ there is any way to test the value of bit 15 of L once it's been written to. Sometimes more software-focused documentation will call L a 15-bit register because of that -- but the hardware makes extensive use of bit 15 of L for multiplication and division, so that's not really fully true. Everything that needs the true value of the bit can still access it through your L15 pin.
I thought I had noticed something along those lines. Thanks for pointing it out. I see L15 is used in certain cases of the WYD pulse and some of the ZIP logic