The Sinclair QL Forum

aalea wrote: Thu Aug 07, 2025 5:45 pm First of all, this is a modification of my interface, I did was not aware that this version exist, and I'm not sure what it do or what kind of revision the maker use to do it, but assume that this is the last, based on the jumper of the top. (btw f|@¬½k the only things that the License of the PCB request is not change the notices, author, copyright, etc... and provide sources, and none is fulfill).

That is my fault, I made that version and havent pushed to git yet as I was hoping to finish a smd version version and push that. SInce im slacking on that will push the as-is to git as soon as I can. Coming back to the change, there is/was pretty much no modification to the schematics, only JP1 as a pin header and another pin to select the bank on the rom, besides that just ground plane and some minor routing. Evertyhing shall behave the same as original work.

aalea wrote: Thu Aug 07, 2025 5:50 pm

t0nyt wrote: Thu Aug 07, 2025 4:11 pm If you try and run the MT3 with just 256kb of RAM expansion it goes mad and scrolls the contents of a ROM on the screen

This is strange and shall not happend, perhaps there are some changes in the interface I'm not aware.

You can't install only MT3 and +256Kb of RAM, and alwais install the +256Kb of RAM AFTER the MT3, never before (never at right), this is because the line that disable the RAM is only in the outside port of the MT3.

If you use the minerva version of the GAL, you can install whatever order you want, but remember that QL need a continuous RAM space, so if you install only +256KB QL will not detect and inform of only 128Kb.

What I did was put a normal 256k expansion board between the QL and MT3 and that's when it went crazy dumping a ROM to screen

Anyway I always plan to use the MT3 with 512K (and not bothered about having 768k)

I've now tested 110 pieces of software (all games as these seem to put the system under most pressure) and only 5 need to change memory size (with res_128/reset xxx) AND run from floppy. I'll re-arrange things so those 5 run from vDrive instead and then it won't matter that the MT3 vanishes when I soft reset to lower memory

Many thanks
Tony

Arleybls wrote: Thu Aug 07, 2025 6:06 pm

aalea wrote: Thu Aug 07, 2025 5:45 pm First of all, this is a modification of my interface, I did was not aware that this version exist, and I'm not sure what it do or what kind of revision the maker use to do it, but assume that this is the last, based on the jumper of the top. (btw f|@¬½k the only things that the License of the PCB request is not change the notices, author, copyright, etc... and provide sources, and none is fulfill).

That is my fault, I made that version and havent pushed to git yet as I was hoping to finish a smd version version and push that. SInce im slacking on that will push the as-is to git as soon as I can. Coming back to the change, there is/was pretty much no modification to the schematics, only JP1 as a pin header and another pin to select the bank on the rom, besides that just ground plane and some minor routing. Evertyhing shall behave the same as original work.

Ok, please, you can use the release option of github, publish it as you sell it, and later make a release of the smd version.

I'm Ok with the modifications, please, do it, I got ideas, I will incorporate the jumper for ROM bank switch in my next revision.

But if somebody bought (example in a flea market) you card in 10 years, is better if he has a place with the documents and changes.

Now that you confirm that there is no changes in the schematic, is one variable less in the equation, and can continue to investigate.

t0nyt wrote: Thu Aug 07, 2025 6:09 pm What I did was put a normal 256k expansion board between the QL and MT3 and that's when it went crazy dumping a ROM to screen

The only "normal 256Kb" interface that I know is from Quest, but I do not have the schematic, so I don't know if there are any missing line or something in the expansion connector that cause the problem.

This shall work, trump shall detect 384Kb, and continue to work (yes, trump can detect 384Kb or any other memory size and not hang,at least).

aalea wrote: Thu Aug 07, 2025 6:35 pm

t0nyt wrote: Thu Aug 07, 2025 6:09 pm What I did was put a normal 256k expansion board between the QL and MT3 and that's when it went crazy dumping a ROM to screen

The only "normal 256Kb" interface that I know is from Quest, but I do not have the schematic, so I don't know if there are any missing line or something in the expansion connector that cause the problem.

This shall work, trump shall detect 384Kb, and continue to work (yes, trump can detect 384Kb or any other memory size and not hang,at least).

Sorry, by "normal" I mean't a board configured to 256kb which is not your 256k+ board for the MT3

It was this one

From what I’ve read the 256k (or 512k) Trump just needed the necessary RAM added to the board to become a 768k with no PAL change required

This part, because the RES_128 in the rom would be writing to ram that did not exist.

XorA wrote: Thu Aug 07, 2025 7:27 pm

From what I’ve read the 256k (or 512k) Trump just needed the necessary RAM added to the board to become a 768k with no PAL change required

This part, because the RES_128 in the rom would be writing to ram that did not exist.

This is the thread about upgrading from 256 to 768 without any other changes (as I read it)

https://theqlforum.com/viewtopic.php?p ... 56k#p60302

t0nyt wrote: Thu Aug 07, 2025 6:59 pm

aalea wrote: Thu Aug 07, 2025 6:35 pm

t0nyt wrote: Thu Aug 07, 2025 6:09 pm What I did was put a normal 256k expansion board between the QL and MT3 and that's when it went crazy dumping a ROM to screen

The only "normal 256Kb" interface that I know is from Quest, but I do not have the schematic, so I don't know if there are any missing line or something in the expansion connector that cause the problem.

This shall work, trump shall detect 384Kb, and continue to work (yes, trump can detect 384Kb or any other memory size and not hang,at least).

Sorry, by "normal" I mean't a board configured to 256kb which is not your 256k+ board for the MT3

It was this one


IMG_4938.jpeg

OK, to be clear, this only happens if you had a custom GAL code for that.
there is not (at least with my GAL code) "normal 256K", any other size different from 512Kb is always +, is always to install as a second card.

Because always, in any case, the middle 512Kb memory area is dedicated for RAM, I only consider this option, there are no any interest in use other size of ram, (in the past, there was quest 256Kb, or Trump ACE 256Kb, but is a question of money, ram was so expensive, that made a 256Kb, has sense, but no now-day).

The other sizes, +256, +128, +192, are always refereed to the last part of the ram, and need to be use at same time of another 512Kb, and the purpose is to be shared with other interfaces that need also memory space, so you can have different hardware interfaces at same time (unfortunately there is other factor that has influence, but I'm been able to have Minerva + mICE + 512Kb + 192Kb + Qbuide + Qsound + Qdisk/trump, all at same time and just work (well more or less).

Ok, thanks

It was just an experiment to see what happened

My plan is to only use 512k anyway

Am wondering if I should remove a memory bank from my original Trump 768 and see if I get the same issue with soft resetting the memory size. But I don’t know how the banks are laid out

I also have a habit of breaking/bending IC legs extracting them. Have already snapped a leg off a GAL today

Many thanks
Tony

After going thru my RESET nnn code I now understand, sorry for being so thick!

The reset code was obviously written with Trump 768k in mind as it tries to copy the TC ROM from $10000 to $C0000, as XorA pointed out, but there's no RAM there with only 512KB of extended memory

The code works with 512K (or whatever) of extended memory WITHOUT a Trump because the copy is irrelevant and therefore does nothing if there's no Trump present

BUT I'm still trying to get my head around why it doesn't work with MT3 with 512K as the ROM for that also cannot be copied to $C0000 at power on or normal reset...

Many thanks
Tony