Vs. Dr.Mario PCB

Myself and a fellow arcade collector have teamed up again to work on a reproduction Vs. Dr.Mario daughterboard for the Nintendo Vs. system.

There were additional complexities to this PCB because it uses a Nintendo custom MMC1 chip, which are not easy to find, and there are no schematics of this board so it was a case of tracking down an original PCB, at some expense, and mapping out all the pinouts. The great thing is that this PCB will be a lot less than an original PCB, so it makes it cheap and more available for the people that would love to own it.

This is the circuit diagram my partner on this project has produced:


Data I/O 29a Remote Mode

Now that I had the Data I/O 29a in a working state I attempted to see if I could get it to communicate with a PC using the Promlink programming software. Unfortunately I fell at the first hurdle as my unit did not have a remote mode available. This can usually be accessed by using the command, “Select”, “F”, then “1” then “Start”, and “Start” again. On my unit this command was not even valid! Interestingly the manual does state that remote mode is “only in models equipped with this option”.

I then noticed that my device had a rom set labelled “324-0029”, whilst my friends unit, which could go into remote mode, had a rom set labelled “324-1024”. Both prom sets were exactly the same and these were labelled “324-1980 Rev A”. So I decided I would copy the 324-1024 roms and try them in my system. Luckily several collectors had some of these roms spare they could post to me (TMS2716’s) and I was pleased to see that once they were burnt, my unit now had the ability to go into remote mode aswell.

Next step was to build the serial port lead to make the connection. This required a 25 pin Dsub male connector and a 9 pin DB9 female connector. I found details of the pins used and connection settings at the following page www.retroclinic.com

Once the lead was made I then had to find copies of the software. After a bit of searching I found a FTP site that had what I needed. The link for the site was ttl.arcadetech.org

This site had various versions of the programs. Most notably 341-1991, and 61. What I discovered is that the unipak works best with 341-1991, and unipak2 or unipak2b works best with 61.

The site also had txt file lists of all the roms, and proms it could burn on each pak, so that was incredibly useful information.

I installed the software on an old laptop running Windows 95, and on my first attempt I was greeted with the message of “contact with programmer established”.

I wanted to try and get the unit running on a Windows 7 PC, soley for the reason that I didn’t want to use multiple PC’s or laptops to run all of my test equipment. I downloaded the software DOSbox www.dosbox.com and installed it on my Windows 7 box. The trick to get this working is to make sure that the serial configuration in the dosbox.conf file is configured correctly. I used the settings:

serial1=directserial realport:com1 irq:4 bytesize:8 stopbit:1 parity:E

Once that was configured I copied the promlink software to the root of my C:\ drive and launched DOSBox. Once the folder was mounted using mount c c:\promlink I was able to launch the Promlink software and establish a connection.

I’ve dumped both rom sets and prom set, and made them available below. If someone else comes across the same issues with remote mode it should be fairly easy to sort out with these files, as I could not find copies anywhere else:

324-1024 Roms (23 downloads)
324-0029 Roms (22 downloads)
324-1980 Rev A Proms (27 downloads)


Vs. Castlevania / Top Gun PCB

Myself and a fellow arcade collector have started working on a reproduction daughterboard for the Nintendo Vs. system which will allow Vs. Castlevania or Vs. Top Gun to run on a dual (Red Tent) or single standalone system.

These daughterboards are very hard to find and can be quite expenisve to buy, so we believe this is a good alternative. We are also looking at the possibility of making another board for Vs. Dr.Mario, but this has some additional complexities we need to work through.

This is the circuit diagram my partner on this project has produced:


Data I/O 29a Repair

I spotted an untested Data I/O 29a programmer with Unipack on eBay a couple of weeks ago, and took a gamble and bought it.

When I received the unit I plugged it in and it powered up, but nothing was displayed on screen. The unit is meant to say “Self Test Ok” if it is working as expected, so clearly something was wrong.

I started taking the device apart, and it was fairly clear that it had been opened before as various screws were missing. The good thing about the unit is that it is fairly modular, and most chips are socketed, so I began testing each chip. I found that my ABI chipmaster failed both the 6802 CPU and 8279c keyboard controller, but passed everything else.

So I bought some replacements for both chips, hoping this would fix the issues.

Whilst I was waiting for the replacement chips to arrive, a local collector lent me his working Data I/O 29a. Although this unit had a different memory expansion board and rom set, I was able to check the Unipack, and my own rom/prom set, as well as keyboard display and that was all working ok.

Unfortunately the roms are TMS2716’s so a different pinout to standard 2716 eproms, and I had nothing to read them with to verify them or save the data from them.

The new parts arrived yesterday, and I put the unit back together with the new chips in place. I then powered on the unit and was pleased to see the message on the display say “Self Test OK”.

The next challenge is to make a serial cable for the device and see if I can get it communicate with PromLink on a PC.


Nintendo Vs Repairs for itruk

I received three Nintendo Vs PCB’s from Klov member itruk in various states. Here’s a video to show how I got on with them:



Sega/Gremlin Frogger Repair

I’ve spent what has seemed like months trying to repair a Sega/Gremlin Frogger PCB. I found the schematics fairly difficult to read, as they use codes to show connections between chips, which is not what I am used too

The board itself had a constant resetting CPU, and I was not able to get it out of this state. Even when I disabled the watchdog the board booted to the same crashed state each time.

I got to a point where my patience had run out, and I asked a fellow collector Sarj if he had a spare working PCB I could compare against. Luckily he had about five sets, and was able to kindly pop one in the post for me to examine.

When I received his board, I was able to swap his sub and logic boards for mine, and use a different interconnect cable between both boards.

To my surprise my main logic board worked fine with his sub-board. Then I tried my sub-board with his main logic board, and found that I was unable to credit a game, and could not test sound, so there was at least one fault here. This made me think that there was issues with my interconnect cable or cable headers. So I tried my own logic board and sub-board with his interconnect cable, and to my surprise the PCB was working!! No CPU resetting!!

So I then used my own interconnect cable, logic, and sub board, back as they were originally. I expected the game to not boot, but it was still working!! Very bizzare!!

The only explanation I can think of is that there was a dirty pin on one of the headers and using Sarj’s interconnect cable had cleaned that somehow. I unplugged and re-plugged my own interconnecting cables many times before this, so it is very odd that the board should now boot as normal.

I put Sarj’s board to one side, now that my own PCB was booting, and found I was still unable to credit a game, or hear any sound. So I looked at the schematics and could see that pin 37 on the 8255 @ IC7 was toggling when I was trying to credit the game, which meant that the resistor array, and capacitor the input went through was working. I could then see that the LS00 @ IC41 was showing no signs of the game being credited at pin 8, and the second 8255 @ IC40 was not being selected. I pulsed some of the input pins on the LS00 to check if I could see any logic changes on the outputs, and any changes at the 8255, and it looked like they were both working correctly, so I suspected that the 8255 @ IC7 was not working as expected. I desoldered this, and checked it with my Chipmaster and it had failed. I replaced it with another 8255, and the game could now credit

I was then able to test the sound and I could hear nothing at all which made me suspect the M51516L amp

It must be noted out at this point that if you don’t have a volume pot connected to the 6 pin header on the sub board you will get no sound. Thanks to Sarj for providing me with one

Even with a pot connected I could still not hear anything. So I swapped the sound chip, an AY-3-8910, for a working one and this made no difference, so I started prodding the pins at the LM741 op-amp. If the main amp was working I expected to hear some noise when prodding the op-amp pins, and I heard nothing. So I desoldered the M51516L amp and fitted a new one. To my relief the PCB was now booting, crediting, and I could hear sound 🙂