At first sight I thougth you were talking about the MC68HC705P9 whose datasheet is pretty available on the net, but then I realized than the MC68HC05P1(-P9) is the same uC in the ROM version, while -705P9 is the EEPROM/OTPROM version.
In my archive I have a venerable copy of the original 1990 datasheet of the HC05P1, -P4, -P7, -P8: they are pretty the same with some variations:
- -HC05P1: base version, 2112B Program ROM, 240B self chek ROM, 128B RAM, 16 bit Timer, 4MHz Crystal/RC Oscillator, No COP, 20+2 General + dedicated I/O pins.
- -HC05P4: like -P1, with 4160B ROM and COP
- -HC05P7: exactly like -P1, with an added serial I/O port (SIOP) and COP
- -HC05P9: exactly like -P1, with an added serial I/O port (SIOP), a 4ch/8bit ADC and COP
Most of these versions but NOT the -P1 are available for free at alldatasheet.com. Expecially I suggest to download the -P9 version, removing the references to the modules not present. The -705P9 also is pretty the same, i.e. the EEPROM/OTPROM version of the -05P9. I think that the most available part was the richer -P9 which probably was the last to be outdated nearly in 2000. This is the link for that (you may found also other versions in the same site)
http://pdf1.alldatasheet.com/datasheet-pdf/view/115172/FREESCALE/MC68HC05P9ACDW.html
Encoder