Expanding the Sequential TOM to hold 16 "cartridges"
I bought my TOM a few years ago, and had always intended to make some sort of switch-able cartridge for it. I decided recently that it would be nicer to have everything inside the TOM, if possible, and control it using the TOM user interface. There are two advantages to doing it this way:
1) Cartridges can be selected without unplugging and replacing EPROMs, which can get damaged by ESD or bent pins.
2) Both the internal sounds and the cartridge can be swapped out, so all 15 sounds can be changed, not just the top 7. There are two "slots" - internal and cartridge. Any of the 16 "cartridges" can be placed in either slot. If a cartridge has seven sounds in it, and is placed in the internal slot, button 8 will not make a sound. All of the cartridges I have made have 8 sounds. If they are placed in the internal slot, all 8 are available. If they are placed in the cartridge slot, only the first 7 sounds are available.
The board plugs into one of the internal sound ROM IC sockets, after both chips have been removed. It also needs A15b and A16b which are not available in either socket, so two short wires are used. I use A15b and A16b instead of A15 and A16 to avoid connecting to the Wonder chip signals. Luckily there are eyelets on the TOM board right where I needed them to be for these two signals.
Here is a photo showing the prototype installed in my TOM:
And here is a photo showing the original version of the pcb, with the two small yellow wires in place:
Here is a photo showing the newer version of the pcb, which has a third wire. The original two wires are connected exactly as before, while the third wire attaches to the lower end of the 10K resistor near the battery. I have added a small circuit which should allow inserting a cartridge (for testing) into the TOM while the TOM16 is installed. In this case, the only sounds available would be the ones on the cartridge, as the TOM16 EPROM is disabled.
How does it work? I added code to the TOM V1.6 OS firmware (the final SCI version) to allow selecting cartridges using the std user interface. Once the selection is made, these values are sent using the Wonder chip in a special way to a PIC micro-controller on my board. That chip presents the two cartridge select 4-bit codes to a dual 4:1 mux that feeds the correct one to an 8 Mbit EPROM. I do not plan to release the PIC code, or provide the source for my version of the TOM OS at this time. The only changes that I made to the TOM OS firmware were for TOM16 support. No other changes were made.
I am currently offering fully assembled pcb's for $105 including Priority Mail shipping to USA addresses. If you are outside of the USA, please contact me for the additional shipping cost. In order to install the board in your TOM, you will need to upgrade the (socketed) firmware EPROM with one that I supply. You will also need to remove the two (socketed) sound ROM chips I610 and I611. And finally you will need to carefully solder three wires, (which I will supply) into small holes in the TOM pc board and in my board.
Here is a schematic diagram of my design.
Here is some information on the header format used in TOM cartridges. And here is some information on the Sequential I-607 Wonder chip.
Here are instructions for installing the TOM16 pc board.
I included the original Sequential internal sound EPROMs as cartridge index 0, plus the four Sequential cartridges. To these I have added six "Drumware" cartridges. That left five open positions. I have filled these with one TR606, two CR78, one TR909, and one TR808 cartridge (designed to complement the Drumware 808 cartridge).
Here is a list of the sounds included in the TOM16, grouped as cartridges numbered 0-15, any two of which can be selected at a time.
Here is the same list as a text file.
Here is an archive containing all sixteen binary cartridge images used, a binary image of the 8Mbit EPROM, and an image of the V1.6 firmware EPROM.
Note: The V1.0 TOM16 pcb did not support using the TOM cartridge slot at all. This was changed on the V1.1 pcb to allow plugging in a cartridge, which would completely disable the TOM16. This did not allow using the TOM16 and the cartridge sounds at the same time. Now there is a way to do that.
An optional mod for the TOM16 V1.1
If you have cartridges for your TOM, and would like to use them and the TOM16 sounds at the same time, I have developed a simple mod which makes this possible. You must have a TOM16 V1.1 pcb, with a 2N3906 transistor on it, to do the mod. You must have decent soldering skills and a short length of fairly thin solid core wire as well. I will not be responsible or help you if you damage your TOM16 by doing it incorrectly. To perform the mod, cut the lead of the transistor that is on the left as you are facing the flat side. Cut it close to the pcb, and bend it up carefully so that you don't break it off. You should bend it with a rounded bend, not a sharp bend right at the body of the transistor, which could cause it to break off. Now fasten a small wire from that transistor lead to the A16b eyelet where one of the small wires is soldered to the pcb. The wire to the TOM pcb also needs to connect to this eyelet. Note that the position of the A16b eyelet was different on earlier boards, so you need to go by the label, not the position. Once you have made this change, inserting a cartridge will only disable the "cartridge" part of the TOM16. You will still be able to select any bank as the internal sounds. When you select "cartridge" on the TOM, you will get the sounds of the cartridge that you have plugged into the cartridge slot. Below is a photo of a TOM16 that has been modified. The person who did it did not have wire so he used the lead from a capacitor, hence the need for the insulating cover. With the mod installed, if no cartridge is inserted, the TOM16 will supply both the internal and cartridge sounds, as before.
Drumware Cartridges for the TOM
Back in the day, a company was offering additional cartridges for the TOM beyond what Sequential was offering. They were called "Drumware". Someone was nice enough to loan me his cartridges so that I could use them in my TOM16cart project, so I am also making the EPROM binary images available here, in case anyone wants to program their own cartridge with them. I have included wave files for each, so you can listen to them easily. There are six cartridges: Rock Drums, Techno Drums, Orchestral, Hippefex 1, Analog Drums (TR808) and Percussion 3 (Latin drum sounds). I scanned the labels, which listed the sounds, and have included the result. I did not have a label for Rock Drums. All of these sounds are included in my TOM16cart.