Cartridge Port: Would a buffer board help with problems?

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DoG
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Re: Cartridge Port: Would a buffer board help with problems?

Post by DoG » Fri Jun 21, 2019 10:03 pm

stephen_usher wrote:
Fri Jun 21, 2019 9:35 pm
I'm wondering how feasible it would be to add pull-up resistors into the address lines on the cartridge. I've no way of making a PCB with a male edge connector and female edge connector.
Could this work for you: https://www.ebay.com/itm/NEW-Atari-ST-c ... 3395781860

You should be able to add your resistors on that board.

EDIT: Sorry, it didn't have the female connector on it. No thru port.

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Re: Cartridge Port: Would a buffer board help with problems?

Post by stephen_usher » Fri Jun 21, 2019 10:06 pm

DoG wrote:
Fri Jun 21, 2019 10:03 pm
stephen_usher wrote:
Fri Jun 21, 2019 9:35 pm
I'm wondering how feasible it would be to add pull-up resistors into the address lines on the cartridge. I've no way of making a PCB with a male edge connector and female edge connector.
Could this work for you: https://www.ebay.com/itm/NEW-Atari-ST-c ... 3395781860

You should be able to add your resistors on that board.

EDIT: Sorry, it didn't have the female connector on it. No thru port.
Indeed, which is a pity.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
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exxos
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Re: Cartridge Port: Would a buffer board help with problems?

Post by exxos » Fri Jun 21, 2019 10:09 pm

Bad address and databus etc is the route of most of my troubles..What you see is "normal" for the ST. Its a wonder the things ever booted or worked from day 1.

Like I said earlier, my diagnostic board wouldn't boot with "Finger on board", so the resistance of my fingers was enough to cause the machine not to boot up... So even down to tollertances on the carts , one cart may work, and another may not.

So I could try and hack on some pullups on the cart and see what happens.. use 4.7K's .... Any sort of loading on the cartridge port will "overload" the 10K pullups normally on the machines... I think on the STE they changed the address pull ups to 4.7K in later revisions.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Cartridge Port: Would a buffer board help with problems?

Post by stephen_usher » Sat Jun 22, 2019 12:58 pm

OK, I put some 4.7K pull-ups on the NetUSBee and...

IMG_1500.jpg
IMG_1500.jpg (62.03 KiB) Viewed 565 times

Still shark fins. It looks like something has a massive capacitance somewhere.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: Cartridge Port: Would a buffer board help with problems?

Post by exxos » Sat Jun 22, 2019 1:02 pm

That's about as good as things get.. But does it help ?
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: Cartridge Port: Would a buffer board help with problems?

Post by stephen_usher » Sat Jun 22, 2019 1:34 pm

exxos wrote:
Sat Jun 22, 2019 1:02 pm
That's about as good as things get.. But does it help ?
Nope.

I'm guessing that the slow rise is causing a timing problem, with the address being read from the bus before the voltage has reached the 'high' level. Maybe the old power supply produced a slightly higher voltage which would mean that the curve would be steeper and hence go above the TTL high level earlier.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: Cartridge Port: Would a buffer board help with problems?

Post by exxos » Sat Jun 22, 2019 1:54 pm

You could try 2.2K instead. Though when it starts getting into these screwy problems.. its why I gave up working on Falcon and STE stuff as the problems never seem to end. Very hard to debug someone else's designs ontop of it all as well.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: Cartridge Port: Would a buffer board help with problems?

Post by stephen_usher » Sat Jun 22, 2019 2:12 pm

I've just tried on the TT.... It helps a bit. More of the NetUSBee operates and it passes the tests, though doesn't actually send packets.

As for changing the value of the resistors, I'll have to get some more resistors. As it was I had to use a mix of 4.7K and 5.3K(?) as I only had sets of ten resistors of each type in the box I bought a long time ago.

P.S. Putting a 'scope on the TT address bus that actually looks really nice and clean, though there's a different form to the signal, in that it's a long high followed by a very short low, followed by a short high and then it goes low until the next cycle. I wonder if that's what confuses the NetUSBee and the Spectre GCR.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: Cartridge Port: Would a buffer board help with problems?

Post by exxos » Sat Jun 22, 2019 2:21 pm

2.2k sils maybe the way to go. Though its possible you may need to change all the pull ups on the address and databus.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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