Difference between revisions of "Videocart dumper"

Revision as of 22:49, 12 November 2013

Sean Riddle built a dumper for the Videocarts to be able to lure the code out without damaging the cartridges. A portable version was shipped over the world to collect rare data from even rarer cartridges.

This page is a work in progress, for now I only present the Pic BASIC Pro code I modified from Sean's original 20MHz PIC16F84 version - as I only had a PIC16C84 at home...

Will complete this with hardware information and compiled code as well.

;   Fairchild Channel F cart dumper version 2
;   2/10/2004 Sean Riddle seanriddle@cox.net
;   Edited from 16f84 to 16c84 by Fredric Blåholtz 03/08/2009
;   Pic BASIC Pro

;    1/5 speed, the nop:s are half as many.

INCLUDE "modedefs.bas"

@ device pic16c84, hs_osc, wdt_off

DEFINE   OSC      4         ;4 MHz oscillator
DEFINE   NO_CLRWDT   1         ;watchdog is off

DEFINE    DEBUG_REG   PORTA         ;serial output on A.0
DEFINE    DEBUG_BIT   0
DEFINE    DEBUG_BAUD   9600
' Set Debug mode: 0 = true, 1 = inverted
DEFINE   DEBUG_MODE   1

k      VAR      WORD         ;another
rom      VAR      BYTE         ;buffer to store ROM

f8phi      VAR      PORTA.1      ;clock signal
f8write    VAR      PORTA.2      ;write signal
f8romc3    VAR      PORTA.3      ;ROMC3 signal

;   CMCON=7               ;turn off comparators
OPTION_REG.7=0               ;weak pull ups on port B
TRISB=$FF                  ;port B is all input

Low f8phi
Low f8write
Low f8romc3

   Debug "Dumping starts in two seconds..."

Pause 2000                  ;wait 2 seconds after reset

;   what I do:
;   clear PC0 with ROMC state 8
;   loop 16384 times
;   fetch 4 bytes into buffer with ROMC state 0
;   dump buffer to serial port
;   clear PC0

      f8phi=1
      f8write=1

      f8phi=0

      @ nop

      f8phi=1
      f8write=0

      f8phi=0

      f8romc3=1
                  ;ROMC state 8, clear PC0.
      f8phi=1

      @ nop

      f8phi=0

      @ nop

      f8phi=1

      @ nop

      f8phi=0
      
      @ nop
         
      f8phi=1

      @ nop
      
      f8phi=0

      f8romc3=0

 For k=0 TO 16383



      f8phi=1
      f8write=1

      f8phi=0

      @ nop

      f8phi=1
      f8write=0

      f8phi=0

      @ nop

      f8phi=1
                  ;ROMC state 0, fetch instruction
      @ nop

      f8phi=0

      @ nop

      f8phi=1

      @ nop

      f8phi=0
      
      @ nop
         
      f8phi=1

      rom=PORTB         ;read databus into buffer
      
      f8phi=0

      Debug rom

Next k

 

End