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Old 27 May 2019, 01:32   #1
Kai
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Lightbulb 8MB FastRAM for A500

So as some of you may have seen in my other thread - I re-did a project from 2007 - an 8MB FastRAM board for the A600 originally published here: http://lvd.nedopc.com/Projects/a600_8mb/index.html

I have taken the schematics, updated them in KiCad 5.1.2 and adapted it for use with the A500.

It's a 95% through hole project, again, for people with unsteady hands, or for those that might be scared of SMT - the only parts that are not through hole, are the 4x DRAM chips (all off the shelf parts from mouser.co.uk - no sourcing new old stock from china!), but these are all SOJ parts, so they should be large enough pitch to solder.

Personally, I use a Yihua 937D, a Hakko chinese clone, that actually is surprisingly good for the £40 it cost me.

I have as of this morning, fiddled with the layout, re-done the silkscreen, compacted everything a bit and re-routed the board so there are fewer via's.

All the content is on GitHub here: https://github.com/kr239/A500-8MB-FastRAM



You can use the original .jed files to burn them on the ATF1502ASV, but i will still be re-compiling them from the original verilog as soon as I have the time.
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Old 03 June 2019, 01:33   #2
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Version 2!

https://github.com/kr239/A500-8MB-FastRAM/tree/v2

Smaller! More SMD! (but still solderable by hand) RED!



Stepping stone to integrating a clock doubler and eventually autoboot IDE (fingers crossed)
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Old 03 June 2019, 07:10   #3
Lord Aga
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Red paint makes it faster
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Old 03 June 2019, 11:56   #4
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Very nice!
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Old 03 June 2019, 12:40   #5
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Awesome
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Old 04 June 2019, 00:53   #6
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how do i get it printed as i dont now how to setup these pcb making sites looks hard , is it already on one where i can order some many thanks
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Old 04 June 2019, 12:35   #7
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Kai, gunna need a stand-in replacement for that memory. Digikey doesn't stock it and mouser only has 3 in stock. Any suggestions?

John
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Old 04 June 2019, 14:08   #8
Kai
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Hmm - looks like digikey and mouser have just run out - an order will trigger their reinventory though.

IS41LV16105D-50KLI is another one to source as well. Both essentially the same.
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Old 04 June 2019, 14:09   #9
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Quote:
Originally Posted by jediknight View Post
how do i get it printed as i dont now how to setup these pcb making sites looks hard , is it already on one where i can order some many thanks
I'll be making these available for individual purchase at £8 + P&P per board as you have to order minimum quantities from the board houses.
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Old 04 June 2019, 14:12   #10
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What i've done, is order a couple of cheap old SIMM modules, with similar chips. Same as SukkoPera's board. I've ordered two different types, and they should be here by the end of the week - so if either of those work i'll let you know here.

GM71C18163CJ6 and GM71C18160CJ6 are the ones i've ordered by the way - both very cheap. They're 60ns instead of 50ns, but if Sukko's github is correct and given your board has similar origins to his, then they should be okay.

Either way i'll only have wasted 10 quid.
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Old 04 June 2019, 14:22   #11
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https://www.ebay.co.uk/itm/4X-GM71C1...EAAOSwDkVZ8boE - those'll do
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Old 04 June 2019, 14:36   #12
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Yep! I was looking at them too. Decided to go for a cheaper pull from an old SIMM until I can verify they work. But if they do, and that link is genuine NOS then that'd be the way to go.

My digikey order goes in today, so I'll let ya know as soon as I have info on compatibility.

Probably looking at the weekend/early next week.

This is the rev1 board BTW, not the new one.

John
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Old 04 June 2019, 15:20   #13
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They have loads of the TSOP ones so i might do a respin (v3) with SMD components, make it even smaller.
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Old 04 June 2019, 15:25   #14
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Who, mouser?

Yeah it seems both mouser and digikey are decidedly anti-soj
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Old 07 June 2019, 20:01   #15
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I think i've got the jed sorted, if anyone wants to test it?

I'm just waiting for a USBISP to come now. I take it the xilinx programmer wont work.

John
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Old 09 June 2019, 18:09   #16
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What did you change in the JED?

I use a cheap USB Blaster clone with my boards, see https://github.com/SukkoPera/OpenAmi...aster/firmware.
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Old 09 June 2019, 18:57   #17
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Oh i didn't change anything... Kai's version doesn't have a jed so i had to compile it from the verilog.

Yeah if i can't get this one to function i'm gunna give yours a go...

Have you built one of your own yet yourself?

John
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Old 09 June 2019, 19:47   #18
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Yes, both my A500 and A600 expansions are tested and confirmed working. The A500 one works with either 4 or 8 MB.
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Old 10 June 2019, 13:19   #19
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The JEDs should work fine - I just wanted to make sure and compile it myself first
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Old 11 June 2019, 20:10   #20
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See anything wrong with this picture?

Sorry Kai, gunna have some of Sukko's boards spun for now until this is ready. I'll be happy to give it a go then, tjough...
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