I have to extract the original program (.hex) from a 40 pin 68HC705C8P. I tried to look over some of the methods that involved around using Universal Programmer. So far, I took the chip to run some readings on Hi-Lo all 100 at one of the avaliable elec-stores, but they said that it couldn't be read. They said that the MCU is unreadable and it might need the other adapter to read it, so I am not entirely sure what to do. Then, I found iProg V86 on the internet the other days and the price is somewhat affordable, so I looked into their software. To no avail, the closest part number is 68HC705B32 which is different part number. In a nutshell, I need a way to read and clone the program inside an MC68HC705C8P. I am not entirely sure if it has been locked from manufacturer or not.

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  • \$\begingroup\$ Is the heading question alright now? \$\endgroup\$
    – Kritanut
    Commented 2 days ago
  • 1
    \$\begingroup\$ I can't quickly find datasheets to see if they are actually related, but I did see this one recently, relating to the MC1468705G2 worldphaco.com/uploads/… I \$\endgroup\$
    – user85471
    Commented 2 days ago
  • 3
    \$\begingroup\$ According to the manual (page 184/185) there is a PROM security bit. If this bit is set the PROM can't be read. \$\endgroup\$
    – nanash1
    Commented 2 days ago
  • \$\begingroup\$ What's data retention like on these parts? It's so old that I'd expect the memory to start failing. \$\endgroup\$
    – Lundin
    Commented 2 days ago
  • \$\begingroup\$ @nanash1 Given enough money, you will likely find a reverse engineering lab that that can extract the firmware for you, possibly with destructive probing methods. These security bits are just for preventing casual copying. \$\endgroup\$
    – Justme
    Commented 2 days ago

1 Answer 1


The following method won't work if the SEC bit was set during programming, see manual page 184/185.

I don't know if there are any modern programmer that support this MCU, but you can build your own. The circuit is explained in chapter 9 of the MC68HC705C8A technical data manual.

A simpler programming circuit is also described on the now offline www.midondesign.com website, which is still available via archive.org.

enter image description here

(source: midondesign.com)

As you can see, it's mainly a serial interface. The website also provides a simple DOS program named "PROG7.COM" which is still accessible via archive.org. This program can be used to dump the PROM if security isn't enabled. The program obviously won't work on a modern PC, but runs on emulation frameworks like DOSbox.


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