Re: VIC-42

From: Gerrit Heitsch <>
Date: Thu, 24 Jun 2021 17:54:18 +0200
Message-ID: <>
On 6/24/21 5:27 PM, Jim Brain wrote:
> On 6/24/2021 10:03 AM, Santo Nucifora wrote:
>> Hi Jim,
>> I don't have a spare 6500/1.  I just have one in a C900 keyboard but I 
>> do have something similar from Zilog.
>> There are actually more than one manufacturer that makes "piggy-back" 
>> chips for development.  These are used so you can just write out an 
>> EPROM and drop it onto the chip so it acts as the internal ROM for the 
>> chip. You can do this multiple times for a prototype until you are 
>> ready for production chips.   I have a Z8613TS in both a ceramic 
>> package and a dip mini-circuit board that shows you how some of the 
>> EPROM wires connect to the die.  It doesn't help your 6500//1 
>> requirement but it does help illustrate how it works.  I have used 
>> these to low-level format Apple Profile hard drives as it requires a 
>> special ROM to do so and that ROM was not public.
>> Here's a pic: 
>> <> 
> The little PCB I completely understand and it makes sense to me. What 
> I'm confused on is how the little 24 pin EPROM socket's lines get under 
> the ceramic packaging and back to the die...

Contact pads on top of the ceramic package. Like the pads on the side 
where the pins are mounted.

Similiar to the DEC Alpha 21064 where they put additional decoupling 
caps on top of the package:

And while I was looking for images, I found that someone else was 
messing around with that controller:

Received on 2021-06-24 18:02:51

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