2708 - 2716 programming

[Jon-A-Tron]

I'm looking for the best solution to burning 2708 eproms.

Is there a generic programmer that will read/write the 2708?

From a search i did a while ago i seem to remember people saying there was but it was expensive and rarely available.
Does anyone know of a homemade version or links to a diagram and info on building my own programmer?

Another point i remember coming up was the option to use 2716 eproms.
Does anyone have info on how to use 2716s in place of 2708s and a recommended programmer for doing that?

Thanks,
JTJonTron2017-12-10 12:44:21

 

[smarty]

I've had this link saved for a long time, the website is now gone but the wayback machine still displays the page, without photos. You can make an adapter to use 2716's in a 2708 board with a couple of modified IC sockets, the will slot in to your pcb.

https://web.archive.org/web/20151019105519/tkc8800.com/page/Substituting-2716-eproms-for-2708-eproms-with-an-adapter

 

[Jon-A-Tron]

That looks an interesting read. I'll use that if i cant find something for the 2708's.
Thanks smarty.

 

[Ace`]

Almost all decent programmers can do 2716s, 2708s are a completely different story. There's maybe a couple of modern programmers that can do them like the topmax (I think) and some of the beeprogs/dataman with a £100ish adaptor.

Your best bet if keeping a look out for an old Data I/O 29b if you want to program them yourself but if it's just a one off someone on here with a 29b will probably help you out.

As for using a 2716 in place of an 2708, you need to double the image and burn it to the 2716. Then either mod the board to take the 2716 or make a small adaptor pcb.

 

[Jon-A-Tron]

I decided to give the 2716 eproms a try out using the guide linked above.

Plan was to load Space Launcher onto the 8 2716 eproms and fit them to adapters before fitting to the Space Fever board. I had seen that Vic had successfully got SL running on cNp's Space Fever and i fancied a bit of this launching action.

Burned the 8 eproms for Space Launcher onto 8 blank 2716s. Burned 1 eprom for the sound board with the .snd file. Fitted these to the adapters i made with the following links:

Pin 24 - 21
Pin 20 - 18
Pin 19 - 12
Pins 21, 19 and 18 cut so dont make contact with board.

Original Space Fever eproms removed (carefully, they have been fitted for over 35years..) and Space Launcher eproms fitted.

Turned on and....nothing. Apart from about 15 white horizontal bars. I did get the explosion sound on startup that i get when i switch on Space Fever but no other sounds or game play.

Any ideas on what i missed?
In the Space Launcher rom files there is 1 other rom file that is marked SF. It has 3 lines of code when i loaded it up. Is this needed somewhere? The other roms are marked as SL so im not sure.
Also, it was mentioned that i need to double up the code on the eproms. I did not do this as i thought the link of the adapter was supposed to direct the code to start from the first 1k?

I would be grateful for some guidance here.

JonTron2017-12-10 13:26:01

 

[Lurch666]

I would check for activity on the pins of the 2716s just to make sure they are connecting properly.

As to doubling up the code this is not necessary because if you grounded the high address pins properly the system will never look at the second half of the eprom.

 

[virtvic]

Does the adapter take care of the different voltages needed for 2716s?
Also, how did you double up the code?

One more thing, make sure you do the sound eeprom too, otherwise you will have incorrect sounds and no Hovis bread advert tune when you game over!

 

[Jon-A-Tron]

My understanding is that the adapter does reroute the voltages for the 2716.

I didnt double up the code. I guess i would just copy and paste the code from the top 1k and put it in the bottom 1k.

 

[Jon-A-Tron]

Vic, can you confirm that the .snd file is the file for the sound eprom? This is what i burned onto ic2 of the sound board. Is that right?

 

[martin8or]

Those wires aren't just poked in there are they?
They need to be properly soldered to the connector or rom leads and you need to keep them as short as possible.
Instead of cutting the leads, what I do is grab the lead of whichever pin you want to isolate with some needle nosed pliers and push the lead/pin out of the back side of the connector(doesn't work with turned pin sockets obviously)

The way you have it now looks impossible for you to solder (you won't be able to push the rom in)so you'll have to think of another way of doing it.

Your best bet is to use a turned pin socket because there's something you can solder the wires to.

Like this but you need to solder the wires http://tkc8800.com/image.axd?picture=/Altair_8800/2716_eprom_adapter/2708_2716_socket_adapter_top_underside.JPG

 

[Jon-A-Tron]

Yes the wires are poked in the back of the connector pin housing. The rom chip fits in and clamps the wire end giving a good friction fit. I then continuity checked each link and every one was <0.001ohm.

I would have liked to do it with the turned pin connectors but i didnt have any at hand.JonTron2017-12-10 17:12:03

 

[virtvic]

I'm pretty sure you're good with that .snd file - If it's 1k, it's the one.

 

[Jon-A-Tron]

Cheers Vic. How many roms did you fit to Chris' SF?
I saw a pic and it was of 7 roms.

The file i have has 8 roms (f1,f2,g1,g2,h1,h2,i1,i2) plus the sound (.snd) file and then another file (sf.prm). This is the file with 3 lines of code.

I have reverted back to Space Fever and it works fine. So i havent done any damage to the board.

 

[virtvic]

You could ask Chris what the stickers ay on them? I thikn there is only 7 roms to change.

I think Space Fever Hi Splitter uses 8 ???

 

[andrewsm]

The diagram you show does not connect the OE of the 2716 to anything. Without this tied low, nothing will happen as the data lines will be tristated. Maybe Ive missed something but this signal needs connected to the CS line so that when the eprom is selected, the outputs are enabled.

The 5V+ is only required for the 2716. Pin 24. The -5 and +12 should be left open and NOT connected.

Also remember to burn the code into the lower 1K of the eprom as the 2716 is a 2K device. The top 1K is effectively redundant due to A10 grounded.

I have successfully replaced a 2708 with this mod on a board I repaired as I didnt have a working 2708 to hand. Plus not wanting to push my test system but it will program 2708s so if you get stuck I can do them for you.

andrewsm2017-12-10 20:24:28

 

[Jon-A-Tron]

OE is connected to pin 20 which is connected to CS via my link wire. The pins 18,19&21 are cut so not connected.

Interesting that you say to put the data in the bottom 1k. I thought that grounding this pin made it only read the top 1k but i must be getting confused. I will re-write to the lower 1k and try again.

I may well take you up on the offer of the 2708s though at a later date. What programmer do you use by the way?

 

[andrewsm]

Grounding A10 will effectively set the address A10 to 0. This means that when addressed only the lower 1K will be seen. The upper 1K never will be used as A10 needs to be 5V for this to happen.

If you have done it the other way then effectively taking all the eproms out of your board will give exactly the same results .

The programmer is part of the Ar81 test system I designed and have sold. It can tackle triple rail devices which I considered to be a useful feature since hardly any modern or cheap programmers will touch. Not trying to sell etc but these sort of posts are of interest to me.

andrewsm2017-12-10 20:40:35

 

[Jon-A-Tron]

Ah, thanks for that info. Thats whats wrong then, i dont have any data for the game to read. Good to know.

So if i put 5v on A10 it would read the top 1k only or the whole 2k at once?

 

[andrewsm]

It would only read the top as all addresses will be +A10 which makes them 0400h or higher.

For a 2716, total addresses are 0800 hex. So the bottom 1K is 0000 to 03FFh. A10 then clocks in so then all addresses are 0400 to 07FF for the top 1K. A10 is high or 5V for this.
andrewsm2017-12-10 21:20:38

 

[Jon-A-Tron]

So its possible to put 2 different 1k game files on to a 2k 2716 eprom and switch between them by puting 5v or 0v on the A10 line?JonTron2017-12-10 21:27:59