retroTINK?

[retroTINK?]

 

Not a stupid question at all. Sometimes the easiest stuff is overlooked.

 

At first I tried a USB cable to the 5V/1A USB port of my TV, as from what I read online, the RetroTINK only needs 1A. It powered on, but just to be safe I grabbed a 5V/3A AC adapter and used that too. Same deal.

In the review I watched, Mike stated that the power supply should be under 500mA... fyi

[The MBX Expansion System]

Having opened one to repair it for another TIer, this is what I have learned:

 

* I have not looked very hard, but I could not find any schematics or details about the unit's internals, let alone programming the thing.

 

* Socketed: The main CPU is a 6809 which is an 8-bit CPU with some 16-bit features. It was designed to be source compatible with the 6800 and 6502, so you did any assembly on an Apple or C64, then you will have a head start on the MBX.

 

* There is a 6821 I/O Chip.

 

* There are two 6116 SRAMs (2Kx8) which would give the unit 4K of 8-bit RAM.

 

* Uses an ADC0809 for analogue to digital conversion, and is still available! Must be a useful and easy to use ADC chip! http://www.national.com/mpf/DC/ADC0809.html#Overview

 

* Socketed: MM52664MBX/N that I could find nothing about. This is probably the ROM since the part number has MBX in it - but that is totally speculation.

 

* Socketed: GI8335 that I could not find any useful information on either, but this is probably the sound / speech chip.

 

* A LM386N-1 Low Voltage Audio Power Amplifier drives the internal speaker and runs off of a separate Zener diode (1N4839 8.2V) regulated supply voltage from the main 7805 regulator. Why? I have no idea since the LM386 will operate from 4V to 12V, and the main board 5V seems like it would be just fine. Also, I/O pin 19 (C2) on the 6821 controls the output gain of the LM386 by pulling pin 5 to ground via a 2N3904 transistor. It seems that the internal speaker can be either on or off, i.e. no volume control.

 

* The main regulator (LM7805) for the board has a really stupid off-board placement and can easily be broken off if you are not very careful when taking the unit apart. The 7805 is very robust and can deal with inputs from about 7.2V to 35V. The secondary Zener regulator (mentioned above) can deal with inputs up to about the same 35V. The 7805 is rated at 1A, and the 1N4738 Zener is rated for 200mA, so the whole unit can never draw more than 1.2A (or the regulators will fail.) Most of the electrolytic caps in the unit are rated for 16V. Thus, you could safely power the unit with any DC supply from about 9V to 12V @ 1A. The tip is positive. 9V is better since the regulators don't have to work so hard and will run cooler.

 

* The secondary Zener regulator mentioned above *seems* to only power the LM386 amp. The main unregulated input voltage is fed to the collector a 2N3904 transistor (not the same one mentioned above that controls the gain of the LM386). The base bias is set via a 200Ohm resistor and the 1N4738 Zener which keeps the base at 8.2V. The emitter is the output and connects the the LM386. From my electronic school days, this configuration would probably be known as an "emitter follower".

 

* The top and bottom of the main board are covered with a metal shell that uses "twisted" tabs to keep them on. While not very hard to remove, you can only un-twist them so many times before they will break off. At least they didn't solder the shields to the board!

 

* There is no crystal for the main oscillator, which I find strange since they are not really that expensive?! However, a quick check with the my O-Scope on pin 38 shows a nice 6.038MHz clock signal.

 

* Connections to the 99/4A are via the joystick and cassette ports. The joystick port is probably used as a serial interface, or maybe a 4-bit parallel interface. But these are just guesses. I thought the cassette interface would be to get sounds from the MBX to come out of the 99/4A's speaker, but that does not seem to be the case. However, since the 99/4A can read data from a cassette, there is no reason that the audio data input could not be computer generated... And, unlike the joystick port, the cassette port is a bidirectional data port! Now that I think about it, that makes more sense. The MBX and 99/4A can talk to each other, albeit slowly, via the cassette interface.

 

* The mic input jack seems to only be that, a mic input. I tried connecting a headphone / mic headset up to the jack, but the audio did not come out of the headphones.

 

* The board is really clean and well laid out. Kind of reminds me of my MSX1.

 

The MBX is a full blown computer only lacking a video subsystem, and it is hard to believe it was an "expansion". With an 8/16-bit CPU running at 6MHz, it kind of puts the 99/4A to shame. It is a better computer than the system it was designed to hook up to.

 

Just curious, has a schematic for the MBX ever been located?

 

Thank you,

[2.2 console question]

out of curiosity have you tried plugging the sidecar into the speech synth then the speech into the 2.2?

 

Yes, I have, and it doesn't work that way either.

 

In fact, it doesn't work that way on a non-2.2 either. I tried it again just to be sure, but I remember that from back in the day. I always had to plug the cart directly into the TI to play the game. It never did work with anything between it and the TI console.

[2.2 console question]

 

I'll have to look at mine; I though they all had >4000, but it's been probably over a decade since I did these.

 

Can you put the Mini Memory in and run Debug with the cart plugged in?

 

Type M4000 and press space to go to the next one. See if you see an AA01 or something along those lines. Pressing . terminates and brings you back to a prompt. Next, try to M6000 and see what is in that space (cart space). If you don't see anything there, try MA000 to see if it's presenting itself in memory expansion.

Unfortunately I do not own a Mini Memory cart. I may be able to borrow one. If I can get my hands on one I will give it try and post the results.

[2.2 console question]

On QI mobo the side port fingers are way tight for things like nano pebs, extender cables and side port carts. Are you sure the cart is fully seating as in you can see all the fingers outside the cart ? If so do other side port items or your PEB work with the console ? Strange.

My 2.2 is and original mobo, not a QI mobo. Even with that being said, I am sure that the carts are fully seated and both of my Miner2049er carts have been tried multiple times. Both carts work in non-2.2 consoles. The expansion port in the 2.2 works. I have operated a speech synthesizer as well as a NanoPEB and a CF7+. I have not connected a PEB to it.

[2.2 console question]

I have only one(1) 2.2 console and two(2) Miner 2049er carts. Neither cart will work in my 2.2 console. When in place, the menu only presents the TI BASIC option. Any ideas why this would be? This is certainly not an issue specifically for me as the 2.2 console only came into my possession recently and I have other consoles I use regularly. I was under the impression that it (Miner) would work. When it didn't (using either cart) my curiosity was peaked.