CURRENT SCHEMATIC

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exxos
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CURRENT SCHEMATIC

Post by exxos »

This is the current schematic for the new STF design.

This still needs checking against the STFM schematic for mistakes.

STF-min.png
STF-min.png (1.19 MiB) Viewed 6134 times

Also see here https://www.exxosforum.co.uk/forum/viewt ... ?f=19&t=15 as the RS232 circuit has been replaced totally.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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tfhh
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Re: CURRENT SCHEMATIC

Post by tfhh »

Hi,
exxos wrote: Tue Sep 05, 2017 4:39 pm This is the current schematic for the new STF design.
This still needs checking against the STFM schematic for mistakes.
Looks very cool. And I see, you´re also a friend of Eagle :)

Jurgen
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Re: CURRENT SCHEMATIC

Post by IngoQ »

:shock: Wow... :)
Ingo :geek:

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keli
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Re: CURRENT SCHEMATIC

Post by keli »

How does the RAM circuit select between the upper and lower half of its 32 bit data bus? I looks like you've just connected each pin of the 16 bit bus twice.
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Re: CURRENT SCHEMATIC

Post by exxos »

keli wrote: Wed Sep 06, 2017 12:53 pm How does the RAM circuit select between the upper and lower half of its 32 bit data bus? I looks like you've just connected each pin of the 16 bit bus twice.
Connects up the same as a 4 MB 72 pin simm.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Re: CURRENT SCHEMATIC

Post by keli »

exxos wrote: Wed Sep 06, 2017 4:27 pm Connects up the same as a 4 MB 72 pin simm.
Yeah, I never understood those hacks either. I see you used to have a 72 pin SIMM kit available as well (and I think I might have asked a similar question before.) If I'm not completely wrong, 72 pin SIMMs do not have ways to target individual bytes. How does updating or reading either one (only CASxLow or CASxHigh asserted) or even two bytes out of available four bytes work?

Since you've produced the 72pin SIMM kits I don't doubt it works, I just can't understand exactly how it works :)
keli
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Re: CURRENT SCHEMATIC

Post by keli »

I think I get what I had wrong. The pinout on pinouts.ru is different. It has A10 and A11 where other pinouts list CAS2 and CAS3.

Mystery solved! :)

Edit That previous pinout was something called "72pin simm with ECC". It's not the first time I've been fooled by the wrong diagram. The correct pinout for a 72 pin simm is: http://pinouts.ru/Memory/Simm72_pinout.shtml
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Re: CURRENT SCHEMATIC

Post by exxos »

Yeah, I use that site mostly. I have seen sites with wrong pinouts. But IIRC, there are some simms used in some odd PC's which do have odd pinouts.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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