REV 3 - REV 5 - The beginning (ST536)

stephen_usher · Post by **stephen_usher** » Thu Mar 25, 2021 7:04 am

exxos wrote: Wed Mar 24, 2021 10:51 pm
stephen_usher wrote: Mon Mar 01, 2021 1:05 pm Anyway, it's good to see that development is continuing. Just out of interest, will the ROM interface 512K ROMs as well as twin 256K ones?
The first problem is A17 has a 2.2K pullup, so its simply GND the pin on the jumper to select bank zero.

So I will have to try and separate that into a 3 way jumper, then have a second to "ignore" high and low selects and wire A17 on the ROM to A17 on the CPU bus to allow 512K decoding.

Capture.PNG

In my decoder I merely had a separate jumper which either connected A17 on the ROM to my decoding circuit or the system’s address line. It was the simplest method I could see.

Post by **PhilC** » Thu Mar 25, 2021 7:37 am

@exxos 64mb of memory.

Post by **exxos** » Thu Mar 25, 2021 10:46 am

I gave all the SMT connections the once over, and found a short as well...

: IMG_6319.JPG (262.18 KiB) Viewed 3845 times

We'll see if it passes memory test properly this time...

EDIT:

It's got past the part it got stuck on yesterday

: IMG_6320.JPG (337.43 KiB) Viewed 3844 times

Post by **PhilC** » Thu Mar 25, 2021 11:18 am

Yay, blame me for building it. Good job I've just got useless some glasses

Post by **exxos** » Thu Mar 25, 2021 11:43 am

PhilC wrote: Thu Mar 25, 2021 11:18 am Yay, blame me for building it.

Works for me!

Will see if I can get the ROM working later on today..

Post by **exxos** » Thu Mar 25, 2021 11:53 am

Managed to squash in the A17/18 select line to the ROM...

: Capture.PNG (54.99 KiB) Viewed 3830 times

Post by **exxos** » Thu Mar 25, 2021 12:48 pm

TTRAM all past good several times. I tried MAPROM 1.8, and opening and closing the floppy window is definitely a lot faster but the floppy contents are still corrupted and I cannot run anything

And it just simply locks up after a few seconds

stephen_usher · Post by **stephen_usher** » Thu Mar 25, 2021 12:51 pm

You shouldn't need maprom for 2.06 to properly detect the TT-RAM with the latest (Sept/Oct) firmware on the TF.

P.S. Have you turned off the cache?

Post by **exxos** » Thu Mar 25, 2021 12:56 pm

stephen_usher wrote: Thu Mar 25, 2021 12:51 pm You shouldn't need maprom for 2.06 to properly detect the TT-RAM with the latest (Sept/Oct) firmware on the TF.

FASTRAM.PRG works fine.. I am using MAPROM to map the rom into TTRAM.. but I dont know what its doing exactly or if it is setting anything else up for simply not doing it properly..

Also note the firmware I am using, I don't know what version it is, as this board is not compatible with the original firmware anyway.

stephen_usher wrote: Thu Mar 25, 2021 12:51 pm P.S. Have you turned off the cache?

Yep.

But simply copying ROM into RAM shouldn't break stuff anyway..

Post by **exxos** » Thu Mar 25, 2021 1:19 pm

Looking through the code, there was still some A31,A30's used.. I have swapped them to A29... but now FASTRAM.PRG just locks up after it loads

I wonder if the software always assumes the board has all 32 bits in use ?

EDIT:

Even GB6's installer locks up now

It is very difficult to follow someone else's code in a language I don't really understand

EDIT2:

I think the software automatically assumes more than 64MB RAM , and assume it declares a larger amount and then locks up because that RAM does not actually exist.. GB6 can install some TTRAM for testing.. and that is working...

exxos's Atari, Amiga & retro forum

REV 3 - REV 5 - The beginning (ST536)

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