Retrochallenge 2016/01 Blog




December 2015 – Getting out the toys for the Retrochallenge


Commodore 64 001.JPG

Commodore 1702 Monitor, C2N Datasette, and “Breadbox” Style Commodore 64

Commodore 64 011.JPG

The Original Commodore VIC-1541 Disk Drive

Commodore 64 017.JPG

Equally Vintage VIC-1525 Graphic Printer


A Somewhat “Enhanced” Screenshot


January 1, 2016 – Attempting to Establish Communications with the Commodore 64


Unless I dust off the Commodore-1600 Vicmodem cartridge, the first order of business is to establish a direct serial link to the Commodore 64 so I can connect a modern PeeCee and share data with the rest of the Internet universe.  I thought I had a commercial dongle somewhere here to convert the TTL level signals on the user port to standard -12 to +12 RS-232C but it appears to have gone missing.  I WAS able to find the appropriate card-edge connector and a MAX232 in my junk-box, so the first order of business is to fabricate a level converter.  The good folks at the Commodore-64 Wiki have the diagram for just such a circuit:

From HwB

 User Port C64                                           C64 RS232


                      |         |

   PA2 M-----------11-|         |-14------------------- TXD (2)

   PB1 D-----------10-|         |--7------------------- RTS (4)

   PB6 K-----------12-| MAX 232 |-13------------------- CTS (5)

 FLAG2 B---X--------9-|         |--8------------------- RXD (3)

   PB0 C---|          |         |--3--|+-|

   VCC 2-----------16-|         |--1-----|              DB25 plug

   GND N------X----15-|         |

              X--|+-2-|         |--5--|+-|



              |---------------------------------------- GND (7)


-|+- capacitor 22µF/16V

-  +

Another connection to the PeeCee is for video and screen grabs.  Although it’s probably easier to grab some of the screen images from the VICE Emulator, I also have a Hauppage TV card on my PC with a composite video input, so I can grab video directly from the original hardware.  In case I ever get anything running worth sharing with the rest of the world, I can put up video captures from the original hardware.

January 2, 2016 – My First Failure


Last night’s work appears to have been for naught.  The MAX232 isn’t giving me any signal and I suspect that I cooked the chip with my grungy soldering iron.  This, children, is why we should always use sockets when fabricating our own circuit boards!

Pissed around with the RS-232 interface for a bit more and decided to give up hardware hacking for the day. Tried to load a vintage copy of "Ghostbusters" and got as far as listening to the intro music. At least Activision chose to use the original theme by Ray Parker, Jr. I'm somewhat impressed by the SID chip -- especially the "Ghostbusters!" voice synthesis in the first second of the theme (how much memory did THAT cost them?.) Still, I think we can wring a better musical performance out of the old Commie... That might become the focus of my screwing around.

January 5, 2016 – A Measure of Success


After three days lost due to work obligations, I was able to salvage the RS-232 Interface today and hook it up to the Linux box. I don't have any real comms software yet, but the following stub was able to send some raw PETSCI to the computer and communicate at 300 bad (7 bits, mark parity.)


Commodore 64 001.JPG


Now, I’m going to quit for the night and watch Battlestar Galactica!