Techincal manual to Emma II trainer by LJ Electronics

[frejk]

Hello all 6502 fans!

I'm new to the board and this is my first post so don't get angry if I post this in the wrong forum section.

As the topic suggests does anybody have access to a technical manual for the Emma II trainer (6502 trainer)?
I'd like to add more RAM to this little beast and would like to have some more info on that which I believe is described in the Technical/Hardware manual.

I found a user manual to this trainer by a simple google-search, actually there is a link to the same manual in a diffrent thread on this forum. ( http://www.ee.siue.edu/~smuren/ece282/l ... manual.pdf )

[BigEd]

Welcome!

I can't help with a technical manual, sorry.

In this previous thread there's a big photo showing the annotations on the circuit board, which tells us
- the system EPROM, a 2716 (2k x 8 ), is mapped at D800-DDFF (6 pages, 1.5k) and FE00-FFFF (2 pages, 0.5k)
- the user EPROM/RAM socket, may be empty, fits a 2716 EPROM or a 6116 RAM and is mapped at F000-F7FF (2k)

The same thread has some info about the routines in the system ROM, including that it has 330 bytes free.

Here are the Emma II threads I found:
- LJ Electronics Emma 2
- Emma II
- SOLVED: Emma II Simulation
There are a couple of others but nothing relevant to this question.
- [133] Gobbledegook
- [69] Emma II 6502

Edit: as the user manual is no longer online at the link, I've taken a copy from the internet archive. See attached.

[frejk]

Thanks for taking the time to reply!

As far as I know from the usermanual that can be found online you are supposed to link/disconnect certain pins on the "empty" DIP socket that can be found on top left in the Adress Deconding section on the PCB (can be seen on picture from the first thread you give link to).

The thing is that I don't know how to link the DIP socket pins in order to map bigger memories than 2k (if possible at all, but I would imagine it is since the 6502 can map 64k after all).

Frankly I'm not experienced enough with the 6502 hardware to reverse engineer the PCB traces from the memory address decoding socket on the board, and since I'm sure it will be covered in the technical manual the job would already be done with how to connect the diffrent pins from the empty DIP socket.

Hoping someone with the manual will see this thread. Please help.

[BigEd]

If we don't manage to find a manual, another approach which might be easier than trying to follow traces is to remove the ICs from their sockets in the little address decode area and then use a beeper (continuity tester) to see which pins go where.

I think two or even three board members have manuals, but they are not regulars and might no longer see messages.

[frejk]

I thought I would post an update on the progress of hunting down a technical manual for the Emma 2, I must say it's not going very well at all unfortunately...
I contacted LJ Create (formerly known as LJ Electronics) and they told me that they don't have any documentation left from the Emma 2 project unfortunately. So that rules that out atleast, now I'm hoping that a friendly soul with the manuals to pop up here and that they would be willing to make a digital copy (or send it to me so I could make it) of it.
The last option would be to figure the pinouts out as you said BigEd, what a nuisance that would be.

[BigEd]

I did reach out to a couple of possible sources, but no joy.

[frejk]

Thanks for helping out BigEd, I really appreciate all help I can get!

I'll see if I can figure out what goes where from the 74LS139 address decoder chip once I get some sparetime, probably in the near future on some weekend.
Stay tuned.

PS.
Got any tips on how to best figure this out manually?

[BigEd]

If you have a multimeter with a beeper for continuity testing, that's best, because you don't have to look. Otherwise, you can probably rig something up with a light bulb and battery, or LED and low-voltage battery. But take out all the chips to avoid damaging them.

[frejk]

I have a few multimeters so the continuity testing will not be a problem.
I guess drawing up some kind of schematics would be the way to go then based on my findings with the continuity testing...

[Dr Jefyll]

BigEd wrote:

But take out all the chips to avoid damaging them.

I would observe this precaution even if a modern multimeter is used. Probably your meter doesn't apply enough voltage or current to damage a chip, but it's hard to know that for sure. And it would be a shame if you ended up having to troubleshoot a board that was in working order.

[frejk]

So I decided to do some reverse-engineering on the address decoding section of my Emma 2 and wanted to share some of my findings. (I won't share my badly drawn schematic; well if somebody REALLY want it I can perhaps photograph it and send it by email...)

Alright here goes, I wanted to put a RAM memory in the "USER EPROM/RAM" socket on the Emma 2. The unit only had an EPROM in the socket when I got it. I'll give up on trying to add more then 2048 bytes of "USER RAM".


In the top left of "ADDRESS DECODING" section on the board I desoldered the jumper-wire on "DECODE SELECT" from pin 7 to 10. Vpp pin on the EPROM fitted will be tied straight to +5V with this jumper-wire.

When I fitted a static RAM memory I soldered a jumper-wire between pins 8 and 9 on "DECODE SELECT" and left the other jumper-wires as they were. Now the R/W pin on the RAM will be connected to the R/W pin on the 6502 through the address decodings glue-logic.

This "USER EPROM/RAM" is mapped at the address F000 to F700, 2048 bytes.

I hope this information will be of some use for someone that is looking for the same thing as I was.

Please look in the thread: viewtopic.php?f=4&t=2388
There you will find a picture of the Emma 2 for reference. (seems to be something wrong at the moment since the picture won't load a bigger version when clicked on)

[phiki]

If you have not found the answers you are after ....
I have originals of both Technical (111 pages) & User (101 pages) Manuals.

Also, I have a very messy but working 'design for a 2Kx8 expansion I made back in about 1988.
It uses 4 x 2114's (1Kx4)

[Dr Jefyll]

Thanks, phiki, for your generosity in offering this material. We've had some other Emma material contributed lately, and I'm not following the details closely, but I do know we're remiss in not thanking -- and welcoming! -- you.

2114's, eh? Wow, I remember those. Back in the day I wire-wrapped a board with 16 of the beasties, hosted in only 8 sites (the chips were piggybacked, two per site). But I replaced the whole lot with a single 6264 after some 110 VAC got into the computer and somehow mysteriously impaired the functionality of the 2114's!

cheers,
Jeff

[frejk]

phiki wrote:

If you have not found the answers you are after ....
I have originals of both Technical (111 pages) & User (101 pages) Manuals.

Also, I have a very messy but working 'design for a 2Kx8 expansion I made back in about 1988.
It uses 4 x 2114's (1Kx4)

I had almost given up on ever finding the manuals for this little beast, I have even been in contact with the manufacturer and they did not have any documentation left (or so they said).

I would be very grateful if you would provide a scan of these manuals! Or have it sent to me or other forummember who is willing to scan these manuals. Keep us/me updated!