WIP: 16C firmware hack for more memory

[brouhaha]

(01-24-2023 08:00 AM)brouhaha Wrote:  I need to hack f MEM to be able to show 4 digits of register count. There's enough room in the display if I shift the "r-" one space left.

I've got the four digit display of the available number of registers working. It was not as hard as I thought. The code was already successfully getting a four-digit count, it just was only putting three digits into the display.

   

The HP microcode that computes the register count is iterative, for the number of registers. It takes the number of hardware 56-bit registers available, multiplies by 14 to get the number of 4-bit nibbles available, then repeatedly subtracts the number of nibbles in the word size. The number of subtractions before underflow is the user register count.

With the stock 203 bytes of RAM, there can't be more than 406 registers (with no program and WSIZE of 4 or less), and 406 iterations doesn't take too long. With 3318 registers, running at normal 16C speed, it takes almost ten seconds. I should probably rewrite it to do a long division.