in-circuit programing 12f675
Look the EEPROM Memory Programming Specification of this devices, from microchip -->
Of the 12f675 :
https://ww1.microchip.com/downloads/en/DeviceDoc/41191C.pdf
And of the 18f252 :
https://ww1.microchip.com/downloads/en/DeviceDoc/39576b.pdf
And design your own programmer, why not
, you must connect PGC ( programming Clock ) PGD ( Programming Data ), PGM ( Lvp enable ), Mclr ( Reset ) Vcc and Gnd ( Power supply ) to your programmer, and respect ac/dc and timing characteristics requierement for programming for these two devices. So, you must do a comprmise of this characteristics to have good programming requierements.
Example for Jdm compactible Prog : ( you must use rs232 signal converter : max232, 233, or level shifter with transistors, or more simply, resistors and diodes...
)
PGC --> RTS
PGD --> In --> DTR, Out --> CTS
PGM --> Ground
Mclr --> Txd
Gnd --> Ground
Vcc --> External power supply and Dc/Dc converter, or Jdm schematic to obtain voltage necessary for programming mode...
Good luck
Regards,