Display Codes
Posted: Wed Jul 13, 2022 9:24 am
Here's an interesting question: Why are the display codes in the Display Code Table ordered in the way that they are?
For instance, it would have been nice if Sharp had put the numeric symbols before the alphabetic symbols. That way if you wanted to print the number "5" on the screen you wouldn't have to do any calculations about what display code to use (not that that is difficult), if the display code for the character '5' was just the value '5' it would be useful.
But apart from that.... there's some cool stuff Sharp did. The pseudo-pixel graphic characters found at the end of the table are all represented by a single bit in the least significant bits for that character. The top-left 'dot' is represented by the LSB (least significant bit). Top-right is the next bit (bit 1 if we're counting from 0). Bottom-left 'dot' is the third bit and bottom-right is represented by the 4th bit. So each 'dot' has its own bit. That makes it very easy to turn dots on and off on the display.
I notice also that they have grouped similar symbols together where the most significant 4 bits don't change but only 1 bit in the least significant 4 bits changes.
Also, along those lines, the filled circle and the empty (or unfilled) circle are easily switched between by inverting the bits! Filled circle is 0111 and unfilled circle is 1000.
Any other patterns in there that are useful?
For instance, it would have been nice if Sharp had put the numeric symbols before the alphabetic symbols. That way if you wanted to print the number "5" on the screen you wouldn't have to do any calculations about what display code to use (not that that is difficult), if the display code for the character '5' was just the value '5' it would be useful.
But apart from that.... there's some cool stuff Sharp did. The pseudo-pixel graphic characters found at the end of the table are all represented by a single bit in the least significant bits for that character. The top-left 'dot' is represented by the LSB (least significant bit). Top-right is the next bit (bit 1 if we're counting from 0). Bottom-left 'dot' is the third bit and bottom-right is represented by the 4th bit. So each 'dot' has its own bit. That makes it very easy to turn dots on and off on the display.
I notice also that they have grouped similar symbols together where the most significant 4 bits don't change but only 1 bit in the least significant 4 bits changes.
Also, along those lines, the filled circle and the empty (or unfilled) circle are easily switched between by inverting the bits! Filled circle is 0111 and unfilled circle is 1000.
Any other patterns in there that are useful?
