Re: 8050 ROM dump

On 4/14/2011 2:00 PM, MikeS wrote:
> Well, I dumped all 4 ROMs that I have and they match Zimmer's images
> perfectly.
>
> ***BUT***
>
> These ROMs are programmed with an active-HIGH chip select (pin20), so 
> a 2764
> (or even a 68764/6) would presumably need to have CS inverted. I think 
> this
> issue has also come up in the C64/C128 world somewhere...
>
> If he didn't account for that then I'm surprised he read anything at all,
> not just "substantially different" code ;-). 
That was news to me.  All of the 2364 pinouts I have ever seen had pin 
20 as active low.  The only reference for that is from this list a 
decade ago:

http://www.softwolves.com/arkiv/cbm-hackers/1/1399.html

But, the information:

1  NC             28  VCC
2  A12            27  S3/-S3/NC (PROGRAMMABLE)
3  A7             26  S4/-S4/NC (PROGRAMMABLE)
4  A6             25  A8
5  A5             24  A9
6  A4             23  A11
7  A3             22  S2/-S2 (PROGRAMMABLE)
8  A2             21  A10
9  A1             20  S1/-S1 (PROGRAMMABLE)
10 A0             19  Q7
11 Q0             18  Q6
12 Q1             17  Q5
13 Q2             16  Q4
14 GND            15  Q3

Doesn't add up to me.  2364s have never had 28 pins.

It looks like I'll need to create a new version of the adapter that uses a hct86 to optionally invert the pin 20 signal.







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