A500 trapdoor memory: free design

[Mq]

Kato, I'm from Poland too, so we can speak in Polish, I suppose:-) hahaha:-)
That problems in Settlers may be caused by wrong Gary adapter.
I use Gary adapter from my design, which was adapted to the next PCB revisions of this extension (eg in Your rev4 PCB).
My Gary adapter has small mistake in turn off circuit (512/more doesn't work), but works perfectly. I can give You PCB for my Gary adapter if You want, because I have few more. Send me PM here or on ppa.pl (You can in Polish:-)).

[Jope]

.. but please speak Polish in PM, the board is in English. :-)

[Kato]

Mq - thanks, I will be able to talk to you soon . For now, I am still waiting for other integrated circuits that are to come to me on the days, so I will try again on my pcb B.4.
Jope - surely Mq meant PM, we respect the forum very much
I am sorry if I write something wrong in English, but I'm not a language specialist That's why I am asking you for your understanding

[Jope]

There is no need to apologise, most of us (me included) are not native English speakers here.

[SukkoPera]

Still waiting for some components to arrive to finalize my build. Anyway I was wondering what happens if I plug a board with the RTC circuit in a 500+: will it override the internal RTC straight away or do I have to change anything on the mainboard? I'm asking since my battery leaked, so I have removed it and have had to repair like 20 traces, so I'd rather not keep a battery in it anymore.

---Expansion Board B6

RTC: RTC72421 B EPSON
Chip Memory 4x KM416C1204AJ-6 SEC
1x 74HC139D NXP (yes 74HC139D Working)
C11 = 10µF ±10% 16V Tantalum (I did not have 4.7uf)
D1 = BAT54C or KL3 0.2A/30V SOT23 Schottky

Various Resistor And Capacitor


---GARY
3x 74HC00D NXP
1x 74HC74D NXP



------Config A500 4chip Memory (1MB chip : 1.5MB Slow)----------
Amiga Rev 6A
with AGNUS 8372A
KICK 1.3

Cut JP2 : see pictures 1 and 2 (Amiga board)
there is a connection (middle pin and pin down)

CUT 4 Wires CAS1L, CAS1U, CAS2L, CAS2U --> XCAS (Expansion Board)

All Jump RAS1
EXRAM Enable
CLOCK Enable (if have RTC)

----Gary Adaptor---
View Picture 3 for position JUMPER
Picture 4 for wire Gary to Expansion Board



**********************************

Thanks to PeteAU, Mathesar, Mq

**********************************

Next step ... TerribleFire,
I expect components...

[PeteAU]

Originally Posted by SukkoPera

Still waiting for some components to arrive to finalize my build. Anyway I was wondering what happens if I plug a board with the RTC circuit in a 500+: will it override the internal RTC straight away or do I have to change anything on the mainboard? I'm asking since my battery leaked, so I have removed it and have had to repair like 20 traces, so I'd rather not keep a battery in it anymore.

Join JP9 on the motherboard, otherwise the two RTC chips will fight each other.

Originally Posted by kamikaze38

1x 74HC139D NXP (yes 74HC139D Working)
...
3x 74HC00D NXP
1x 74HC74D NXP

You used all CMOS HC (not HCT) chips and it worked? Surprized...

[bruktmoped]

I bought some 72-pin RAM off ebay, was sure it was the correct kind, but turned out to be soj40 instead of soj42. Am I screwed? (I googled the soj40, and it seems they use them for the A600 piggyback mod. 2 chips for 1MB extra Chip RAM)

Originally Posted by PeteAU

You used all CMOS HC (not HCT) chips and it worked? Surprized...

Hi PeteAU
Yes all chips is CMOS HC not HCT
Working

[Chain]

Ordered 5 pcs, got 8pcs
looks like some chinese operator wants to make ten of them, but stopped it at last

way to go elecrow

[AwoLStill]

Like the B52! - a nice touch

[PeteAU]

Originally Posted by bruktmoped

I bought some 72-pin RAM off ebay, was sure it was the correct kind, but turned out to be soj40 instead of soj42. Am I screwed? (I googled the soj40, and it seems they use them for the A600 piggyback mod. 2 chips for 1MB extra Chip RAM)

Screwed? Yes. Do you already have PCBs ordered? Maybe I can dig out a SOJ40 variant I put somewhere.

Originally Posted by Chain

Ordered 5 pcs, got 8pcs
looks like some chinese operator wants to make ten of them, but stopped it at last

way to go elecrow

It's normal for elecrow, but maybe 3 boards are scratched or imperfect?

[\\.\]

I have an expansion slot in mine but from what I can tell about the official ones is that they are in a metal box, this one isn't, its an obvious 3rd party after market what-cha-ma-call-it and it has a switch on it that lord knows what it does. Dispenses fun size crunchy bars from the vending machine on the IIS or something...

So any ideas on what the switch does?

[Mq]

@kamikaze38: congratulations, good work!

About HC cmos IC's: I saw in many projects people use them and they works with TTL signals usually. I was testing HC series in the RAM extension for Atari 65XE, and they works for me too.
HC cmos has different levels of high and low, but I noticed if we give them signals which fits in the high and low levels, then they works the same as HCT.
If we give supply voltage 5V, then they give us proper levels accepted by TTL's too.
HCT are actually near same as HC, but with signal levels matched to TTL.

[demolition]

Originally Posted by \\.\

So any ideas on what the switch does?

Usually the switch toggles the expansion on and off. Only to be used while the machine is turned off though or it will crash.

[bruktmoped]

Originally Posted by PeteAU

Screwed? Yes. Do you already have PCBs ordered? Maybe I can dig out a SOJ40 variant I put somewhere.




It's normal for elecrow, but maybe 3 boards are scratched or imperfect?

If you got schematics for a soj40 variant it would be fantastic! I got several ram sticks I ended up paying too much for, so it would be fantastic if it turned out that I could still use them.

[PeteAU]

Originally Posted by bruktmoped

If you got schematics for a soj40 variant it would be fantastic! I got several ram sticks I ended up paying too much for, so it would be fantastic if it turned out that I could still use them.

No schematic, but gerber files added to post #2 (first page). No idea if they work though. Let us know the result.

[bruktmoped]

Wow! Thats awesome! Thanks! Due to chinese new years, it might take a while untill I get my PCBs, but Ill let you know how it goes! Can I just use this the same way as the soj42 pcb?

[SukkoPera]

I have finally tested the boards I received from Mathesar in the following configurations:
- 1 MB chip on A500+
- 512 KB slow on A500 Rev.6A

Both are working great, both for the extra memory and for the RTC.

Now I've built a Gary adapter and added 3 more RAM chips on the 512 KB expansion to get 1 MB chip + 1.5 MB slow on the 500, but then I realized I'm still missing the '139, so I will have to wait even more, grrr!

Anyway, could anyone recommend how to set the various RAS jumpers to achieve this? Oh and what's the 512K/More jumper exactly for? I think it would be a good idea to add a table of the most commonly used jumper settings in the first post.

Another thing: I have imported the design in Kicad and made some changes: I have removed all the hardwired jumper connections since I prefer to solder real jumpers and set them as needed (@katarakt will like this!). I have also improved the ground plane a bit, mainly on the Gary adapter. Kicad did a good a job (for the PCB at least, not as much for the schematics...), but it messed up the whole silkscreen (had to manually fix almost every label!) and it failed to import the disk and B52 images. Could anyone provide those as plain images so that I can reimport them manually? Thanks.

PS: Of course I plan to contribute my modified PCB once it's tested.

[katarakt]

Originally Posted by SukkoPera

I think it would be a good idea to add a table of the most commonly used jumper settings in the first post.

Another thing: I have imported the design in Kicad and made some changes: I have removed all the hardwired jumper connections since I prefer to solder real jumpers and set them as needed (@katarakt will like this!).

Excellent idea, there is still much confusing because important informations are all around in the whole thread and took too much time to find detailed info again. Would be perfect if ALL important informations are in one pdf in the first topic.

And yes, i like this with removed hardwired jumpers! I've also removed them in my pcbs . Don't know if they're working because still waiting for one part (i've ordered 3 components wrong). I don't know why these are all hardwired in original layout

The 512/More jumper i think is if you want to turn the ramexpension off completely. If you turn of only the ram expansion, gary is still active with more memory as i know (also an information somewhere in this thread if i remember correctly).

Still some optimization needed to the board for future revision:

- C20 change lead space straight from 2.5mm to 2mm because every better capacitor has 2mm with fits there in diameter!
- Remove these hardwired jumper traces
- add a wire from the LED resistor to 3 pin so we can use a 3-pin connector and a switch with integrated LED or put a seperated LED somewhere anywhere we want with connectors (see picture below) ...or mybe is a 4-pin better if i want to sperate LED and switch....hmmm....what do you think ?

edit: i think 4-pin is better, because in that way for example you can put led on the top and switch on the back on amiga, so everyone can put switch and LED wherever he wants