[Coco] 512K upgrade

[Kip Koon]

Hi Bill!
I apologize for not being available the last day or so.  I've been busy with
a customer working on his wife's laptop.  It had 76 Trojan viruses on it.
At least one of them was taking pictures with the webcam and sending them
back to somewhere.  Scary huh!  
After receiving an email from Sylvain, the buddy of mine in Canada with whom
I traded my 512KB SIMM Memory Upgrade PCB for his video converter, about an
SRAM version of the 512KB Memory Upgrade he was working on, I revisited my
SRAM version of the 512KB memory upgrade and eventually figured out how to
implement it with just 4 chips.  I used two sram chips instead of one to
reduce the number of logic chips I would need.  My previous design used 4
latch chips since I could only find 8-bit latches.  Well, guess what?  I
found a 74F843SPC 9-bit addressable latch from Fairchild in a slim 0.3"
24-pin DIP package!  I was very pleased to see this little gem.  I
immediately went to work updating my 512KB SRAM Memory Upgrade and I must
say the design is very nice indeed.  A 4 chip solution using through-hole
DIP chips!  I love this stuff!  
I would have chatted with you today in my office, but I left my cell phone
at home.  It was charging overnight, so I didn't even remember to check it
before I left home yesterday morning.  I hope to chat with you tomorrow.
Take care buddy!
Kip

-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
Behalf Of Bill
Sent: Friday, March 07, 2014 4:06 PM
To: Coco Enthusiasts
Subject: [Coco] 512K upgrade

I just got a 512K upgrade board and need to test the memory. I know I've
already asked this once, but I need to know what the POKES or PEEKS are to
test it. Or, what should MFREE show me in NitrOS-9?

 

Thanks


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