HP-85 A.K.A Capricorn

[acoto]

Commodore 64 Basic and Kernal dissasembly here:
https://github.com/mist64/c64rom/blob/ma...rom_en.txt

*** perform COS()
.,E264 A9 E0 LDA #$E0 set pi/2 pointer low byte
.,E266 A0 E2 LDY #$E2 set pi/2 pointer high byte
.,E268 20 67 B8 JSR $B867 add (AY) to FAC1
*** perform SIN()
.,E26B 20 0C BC JSR $BC0C round and copy FAC1 to FAC2
.,E26E A9 E5 LDA #$E5 set 2*pi pointer low byte
.,E270 A0 E2 LDY #$E2 set 2*pi pointer high byte
.,E272 A6 6E LDX $6E get FAC2 sign (b7)
.,E274 20 07 BB JSR $BB07 divide by (AY) (X=sign)
...
*** perform TAN()
.,E2B4 20 CA BB JSR $BBCA pack FAC1 into $57
.,E2B7 A9 00 LDA #$00 clear A
.,E2B9 85 12 STA $12 clear the comparison evaluation flag
.,E2BB 20 6B E2 JSR $E26B perform SIN()'
...

have fun!