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

Tuesday, June 18, 2013

RR Prommer V1.0 EPROM Burner User Manual

For building the Z80 Minisystem I needed a cheap EPROM burner. I searched and found one. It was the "RR Prommer V1.0". This was back in 2008 or 2009. For the Vectrex Cartridge I will need it again as I wanted to have a simple design at first as I'm not possessing much knowlege about the internals of the Vectrex and the 6809 cpu.

But what is this? I can't find the manual. Just look at the programmer.

The type of EPROM you want to use has to be set using 5 jumpers. But without a manual it's rather difficult to know which settings is the right one.
So I googled a little bit and guess what. The Manual just has disappeared. The Internet actually has forgotten something. (At least I'm unable to find It with 20 minutes of searching >_<)

Luckily I digged It up again from a harddrive of my last pc so I have it again. As other people als might have this problem I like to share it for download here.

Also If you are unable to find the software this guy here has developed a linux program to use it. zprommer.
It works as the "RR Prommer" is actually a clone from an old Batronix EPROM burner. I don't know anymore how I got this one. But It works great using the EPROMs 27C256. I can't say more now and I hope It works also with 27C2001. If not I'm pretty screwed :-D

Friday, June 14, 2013

Vectrex Homebrew Cartridges

Last year I got myself the famous Vectrex console.For those who don't know it: The Vectrex made by MB is the only homeconsole with a real vector graphics display as It was used in early arcade games like Asteroids, Lunar Lander and Tempest. Because of this design it's impossible to use a standard television with this system as these devices are only able to rasterize a picture line by line. Vector systems on the other hand directly control the beam of the cathode ray tube to draw dots and lines.
This is why the vectrex has a built-in monitor ... which can be destroyed by software.

Here is a picture of my unit.

Here is another picture of my units tube.

This "hole" is not photoshopped. The small dot indicates that the fluorescent layer was burned away at that point. Talking about "Killer Pokes" here. It's like a damaged pixel on a TFT monitor. It's always there and you have to look at it. Anyway....

According to Wikipedia the Vectrex has only 20 official games released in europe which is sadly not a lot. To overcome this problem and because programming games with vector graphics is awesome as hell this platform got a great homebrow community. A lot of these games are released on custom manufactored cartridges and also a few with integrated non-volatile memory for highscore savings (which is not common on this device). But not all of them.

As this device is not that popular not a ton of "flash cartridges" exist that let you burn your own games onto. A very good example is the VecFlash and the VecMulti made by Richard Hutchinson. Sadly both are sold out at least since 2012-08. I tried to contact him at that point but the status hasn't changed since then. Both cards were very sophisticated. In special the VecMulti which offers to load games from MicroSD and has a debugging port for homebrew development.
Another alternative would be to destroy an existing card by replacing the rom by an eprom and then use this one. Also you can use extra adress lines to select different games. This is how a lot of "MultiCarts" are designed.

A lot of time passed since then and I thought myself it would be funny to make a EPROM based solution myself. It will not be as great as the "VecMulti" but it will suit most of the needs. I finished a long ago started design today and ordered the PCB. So stay tuned.

The only downside with my design is the lack of backup memory which is used at least by the games Thrust, Protector and Y.A.S.I which are one of my favourites. I couldn't find schematics which show how that works and where the needed EEPROM is applied but the design is made flexible so it may be possible to add that later.