Introduction
A reprogramable cartridge lets you program your own games for the VB and play them on the VB hardware. Basically we take an existing game, remove the static ROM chip and replace it with a reprogramable EPROM chip. This way when you want to change the game in the EPROM you simply have to erase the EPROM (using a UV eraser) and reprogram the new game/code into the EPROM (using an EPROM programmer).
Equipment
| Quantity | Part | Pins | Description | Mouser Part# | Price each |
| 2 | 27C080-90ns | 32 | 8Mbit (1MBx8bit) 90ns UV-EPROM | 511-M27C801-90F | $10 |
| 2 | 40 pin ZIF socket | 40 | holder for EPROM | 535-40-526-10 | $7 |
| 1 | Low Voltage Soldering Iron | ~$20 | |||
| 1 | Spool of Solder | $1 | |||
| 1 | Spool of Wire Wrap wire | $1 | |||
| 1 | 3"x5" piece of perfboard | $1 | |||
| 1 | Mario Tennis VB game | $5-$10 | |||
| 1 | 32 Pin EPROM programmer | $100-$200 | |||
| 1 | UV EPROM eraser | $20-$40 |
The 27C080 pair of EPROMs will be big enough to play any VB game (1Mx16) total size. You can substitute a smaller EPROMs like the 27C040, or 27C020 to reduce the cost, but the savings are not large ($5-$10). Also a knife and a pair of needle nose pliers will come in handy as well.
All parts are available from Mouser Electronics
How To
Start by opening the VB cartridge using a pare of needle nose pliers to remove the security screws. Alternatively you can cut a notch in a flat blade screwdriver to open the cartridge.
Next carefully remove the original ROM in the cartridge, taking care not to damage the circuit board in the process. The ROM is the big 44 pin chip in the middle of the cartridge, you can either cut all the pins from the ROM or use a soldering iron and a needle, carefully prying up each pin as you heat up the solder to it. Don't worry about damaging the original ROM, we will not be using this part any more. Once the ROM is removed, verify that you have not accidentally created any shorts on the circuit board. This is critical a short would stop the VB form reading your EPROM successfully We need a place to mount our sockets, to hold the EPROMs securely in place. We will attach the perf board to the back of the cartridge case for this purpose. Cut the perf board so that a portion of it can be attached to the back of the VB cartridge, with enough of it sticking out so you can place both sockets on the board. I secured my perfboard to the inside of the cartridge cover, cutting a small notch in the back of the cartridge so the halves could be put back together with the board sticking out the back.
Once everything is cut to size we can solder our sockets to the perfboard, be sure they are facing the back of the cartridge, so we can access them while the cartridge is in the VB unit. Just use enough solder to tack them in place (tinting every pin), we will attach wires to the sockets later, and to much solder would cause troubles.
Now for the tedious part, we must run wires from every pin on the socket to the appropriate pins on the edge connector of the VB cartridge. We will attach the wires to the edge connector because it is larger and therefor easier to solder to than the pads that the original ROM was attached to. There are about 64 wires to run, so be patient and take your time. A mistake here would be hard to correct.
Finally we simple reassemble the whole contraption, we are ready to program an EPROM and test it out. When programming you will need to tell the programmer that you are programming a High Byte/Low Byte sequence, so that it programs the upper 8 bits to one EPROM and the lower 8 bits to the other. Now plug it all in and give it a spin.
Schematic
Reprogramable Cartridge Schematics - vb_cart.pdf, 32_pin_cart.pdf and 4x_pin_cart.pdf
32Pin EPROM
40 pin EPROM
44pin EPROM
Images
Here are some pictures of my own cartridge's:
- A 40 pin EPROM based off of a Mario Tennis game
- The Start of a 48 pin flash based cartridge based off of Wario Land
- A 32 pin EPROM based off of a TeleroBoxer game
MISC
VB to Gen adapter
- text document describing how you could use a Genesis
copier to program the VB.
VBRoms
- A list of known VB games, indicates what games have battery backed SRAM chips.
The unofficial VB Programmers manual (HTML format),
(Word 95 format),
(PDF format)
- Includes a full pinout of the VB edge connector.
IO56vb program
- A program to read VB roms using an IO-56 or IO-48 card, based
on Pascal Fibers IO-56 work