exxos blog - random goings on

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exxos
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Re: exxos blog - random goings on

Post by exxos »

I was thinking about the fast RAM board again... This was going to be a part of the SEC booster (and probably still will be, but it is basically on hold that project for the moment).. But adding SRAM to a expansion board for the next remake motherboard would be relatively simple.. Things like the IDE board have a large PLD which could easily take care of the fast ram decoding with only a small number of jumper wires to the board..

So I have stripped back the SEC design (Most of the RAM was already rooted anyway) which basically leaves me with this...

fr.jpg
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So if I can get it squashed into a DIP68000 type layout, then this could be a easy plug-in expansion board for the next remake motherboard..

With the likelihood of 16MHz being possible on the next motherboard, we could easily have 8MB of 16MHz Fast-RAM.

Of course when the FPGA MMU is created and working, we would actually render the fast ram stuff totally obsolete anyway. Where we would just basically have 14MB of ST-RAM running at 50MHz for example.


EDIT:

Only just fits...
3.jpg
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PhilC
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Re: exxos blog - random goings on

Post by PhilC »

That does look good actually but wont there be a clearance issue? Could just rotate the chips 90 degrees I guess?
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Re: exxos blog - random goings on

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PhilC wrote: Tue May 07, 2019 3:11 pm That does look good actually but wont there be a clearance issue? Could just rotate the chips 90 degrees I guess?
It does fit, but I already wired them up like that, my sanity can't cope with routing those chips again :)
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Re: exxos blog - random goings on

Post by PhilC »

exxos wrote: Tue May 07, 2019 3:13 pm
PhilC wrote: Tue May 07, 2019 3:11 pm That does look good actually but wont there be a clearance issue? Could just rotate the chips 90 degrees I guess?
It does fit, but I already wired them up like that, my sanity can't cope with routing those chips again :)
LOL ok, I'll shut up then. P.s. sign me up if you need a Guinea pig for it. Be interesting to see if it works with this Pak.
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Re: exxos blog - random goings on

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PhilC wrote: Tue May 07, 2019 3:15 pm LOL ok, I'll shut up then. P.s. sign me up if you need a Guinea pig for it. Be interesting to see if it works with this Pak.
Its not a stand alone fast-ram board.. it needs external decoding like I said earlier....
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Re: exxos blog - random goings on

Post by PhilC »

Oh yeah, missed that bit :shock:
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Re: exxos blog - random goings on

Post by exxos »

Basically done... I gotta add in a SRAM enable port next....

VCC & GND are flood filled on top and bottom layer (not shown )

4.jpg
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Re: exxos blog - random goings on

Post by exxos »

Been doing a little bit of tidying up on the schematic and board, I have also added in a total of 4 DIP 68000 sockets which will be basically the expansion sockets..

For example the SEC booster, fast-ram board, IDE can use 3 sockets easily.

h2.jpg
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Re: exxos blog - random goings on

Post by exxos »

Added the OE header to the fast-ram board :)

1.jpg
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Good solid gnd layer as well :)

2.jpg
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Re: exxos blog - random goings on

Post by Icky »

Nice!
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