ALPHA MODIFICATIONS

All information relating to the Alpha plus all the WIP threads etc.
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exxos
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Re: ALPHA MODIFICATIONS

Post by exxos »

Forgottenmyname wrote: Thu Sep 27, 2018 4:22 pm If you've kept up, your board should now look a little something like this :)
*real* computing this is :thumbup:
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Icky
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Re: ALPHA MODIFICATIONS

Post by Icky »

Forgottenmyname wrote: Thu Sep 27, 2018 4:22 pm If you've kept up, your board should now look a little something like this :)

P.s. not done the 16mhz mmu fix as it was optional.
:coolpics: - Looking good.
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PaulJ
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Re: ALPHA MODIFICATIONS

Post by PaulJ »

Icky, I'm putting in missing pullups on cpu. Your picture with the extra sip pullup pac shows a pullup connected to pin 10 (dtack) but nothing on pin 9 that is identified as needing a pullup. Initially I put the extra pullups in according to your picture but dtack then reads ~680 ohms which means the 1k pullup is ther and the 2.2 k is in parallel with it. Did you get the rw pullup on dtack or am I a marble short of a full deck?

Paul
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Re: ALPHA MODIFICATIONS

Post by exxos »

Looks ok to me...

11111111.JPG
11111111.JPG (180.69 KiB) Viewed 6639 times

DTACK is on RP1 (1K) so doesn't need a pull up, Icky doesn't have one on that pin, its RW.
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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Re: ALPHA MODIFICATIONS

Post by PaulJ »

Your right, I'm one marble short. The prior picture is 90 degree different and I've been looking at it from this perspective.

Paul
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Icky
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Re: ALPHA MODIFICATIONS

Post by Icky »

PaulJ wrote: Sat Sep 29, 2018 9:32 pm Your right, I'm one marble short. The prior picture is 90 degree different and I've been looking at it from this perspective.

Paul
Hi Paul. Nice to see you working on the board.

Why not open a topic for your pics and experience in the Alpha User Builds section. https://www.exxosforum.co.uk/forum/viewforum.php?f=64

We would like to see where you are and some photos.
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Re: ALPHA MODIFICATIONS

Post by PaulJ »

I'll put something up later today.
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Re: ALPHA MODIFICATIONS BGACK pull-up

Post by PaulJ »

Do we need another pullup on BGACK pin 12 on processor. Once SJ1 is shorted it connects the 4.7k pullup on GLUE_BGACK (pin 40)? I may just change R150 to 2.2k?

Please advise..
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Re: ALPHA MODIFICATIONS

Post by troed »

Is the description for RESET FIX complete? Icky has moved the leg of the resistor which is not in the description, but without it the cut tracks don't really make sense.

edit: Ah, read further down. Also the resistor connects to internal plane I guess. I'm not used to 4 layer boards ;)
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Re: ALPHA MODIFICATIONS BGACK pull-up

Post by exxos »

PaulJ wrote: Tue Oct 02, 2018 5:54 pm Do we need another pullup on BGACK pin 12 on processor. Once SJ1 is shorted it connects the 4.7k pullup on GLUE_BGACK (pin 40)? I may just change R150 to 2.2k?

Please advise..
There is already a pull-up on it so it resistor is not needed as previously thought..
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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