Saturday, June 29, 2013

Vectrex EPROM Cartridge finished

Today the PCBs of my EPROM Cartridge arrived. Of course I soldered and tested it directly. The EPROM used here is the 272001 which is programmed using the already mentioned RR-Prommer.
The image to burn is generated by a small linux tool written in C, which reads a list of pathes to ROM images and arranges them according to the limitations of the hardware.
The Cartridge contains 256kb of memory. Supported ROM sizes are 8kb, 16kb and 32kb. ROMs which don't fall into one category are expanded by the tool to fit one.

The hardware is rather simple but offers some glue logic to support the various ROM sizes. All Images need to be aligned on their size. The used algorithm places the bigger ones at the beginning to simplify this problem.

At last the tool generates a list likes this here to tell you how you need to set the dip switches to select the wanted game.

Wormhole              -----
Gravitrex             --.--
Thrust                -.---
Protector + Y.A.S.I   -..--

Sadly I can't test the save feature yet as I've forgotten to add the needed EEPROM to the basket >_< doh.

And yes it does work like a charm. At first I did have a fear that my beloved Vectrex explodes (or implodes) but electrical engineering did again win this time.

Yaaayyy !!!! To convert the graphic of my snail I've written myself a tool in Java that grabs a SVG file and then fetches the koordinates of pathes out of it. I think they will be also one post about this soon.

Limitations compared to the a lot better VecMulti:
  • No Bank-Switched Games
    • Image not allowed to be larger than 32kb
  • Only one EEPROM for savegames.
    • So only one saving game on one cart.
    • Still: EEPROM has TO92 package and can be removed easily.
  • No Debugging-Port


  1. Replies
    1. Thank you.
      Maybe it's constructed well. But the design sure has some flaws. I'm learning to develop for the Vectrex at the moment. For testing I use the emulator ParaJVE which lacks some authenticity. The snail on the photo was first drawn in one go. On the emulator it looked great but on the real machine the latter drawn vectors were just wobbling around. I corrected this by dividing the graphic in two parts so I could insert an integrator reset in between. Mistakes like this could be avoided if testing on the real machine would be an easy and fast task. The VecMulti offers a debugging port which lets you send programs over the serial port. For testing this is great stuff and I kinda miss it here.
      I didn't knew that the emulation is so imperferect here. Even the brightness is calculated wrong. I would try another emulator but It seems that this machine is not blessed with them.

  2. Replies
    1. You think? Well thanks^^ It's rather primitive. But Vectrex Multicarts with reprogrammable Memory is hard to find today.

  3. Nice, do you sell these pcbs somewere or do you give the sheme out so people can make them on there own?

    1. Hello Oliver. As I've ordered these PCBs at beta layout so I had a minimum charge of 3. I still have one of them to sell. I would give you one unsoldered pcb for 29€ plus shipping. This is really just the self cost price as beta layout is quite expensive.