(Fwd) Re: 6530 replacement

From: Ruud_at_Baltissen.org
Date: Sat, 02 Nov 2013 12:08:32 +0100
Message-ID: <5274DD30.22130.863B1@Ruud.Baltissen.org>
Hallo allemaal,

The 6530 replacement works! 

At the end I used what was mainly Martin's design. But instead of 
using jumpers I wired all unused address lines to +5V, that is, A10 
and higher. I copied the contents of the 2516 into a 2716 and... 
nothing. I connected my logic analyser and that one only showed $AA 
during all reads. 
After some comparisions etc. I opened the editor of my programming 
tool and.... all $AAs on the screen. HUH ??? But after some 
scrolling I found the real data. Then it hit: A0..9 is only 1 KB 
and a 2716 is 2 KB! In this case the program was residing in the 
bottom 1 KB. Thus A10 had to beconnected to GND? Indeed this was 
the case on the expansion board. So I rewired A10 and.... nothing 
again :( And my analyser only showed nonsense. From frustration I 
"throwed it in the corner". 

Today I had some time and within minutes I found out that I rewired 
the wrong wire: Vpp instead of A10. That probably explained the 
nonsense my analyser read. 

FYI: I tested this on a SFD-1001, directly on the main board, thus 
not using the little expansion board.

The Eagle schematic is free, as well as the board that goes with 

Kind regards / Met vriendelijke groet, Ruud Baltissen

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Received on 2013-11-02 12:00:06

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