[Coco] Disk Controllers

[Arthur Flexser]

Robert, with a 27128, I think you'd also need to run a wire to the
edge connector to enable the upper 8K.

Here's a way to do it without any adapter at all, guaranteed to fit:

>Here's what you need to do to get it to take a 28-pin EPROM. First, on the
>EPROM, bend pins 20, 23, and 26 outward slightly so that they don't plug
>into the socket.  The EPROM will plug into the socket with its pins 1, 2,
>27, and 28 hanging off the end of the socket.
>
>An E stands for a pin of the EPROM, S for a pin of the socket.
>
>Connect:
>  1E to 27E, 28E, 24S (alongside bent-out 26E)
>
>  2E to 21S (alongside bent-out 23E)
>
>  18S (alongside bent-out 20E) to bent-out 23E
>
>  22E to bent-out 20E
>
>  bent-out 26E to pin 37 of the edge connector
>
>
>That last connection, involving running a wire to the edge connector, is
>only necessary if you anticipate using a 16K EPROM in the controller.

Art


On Sun, Dec 29, 2013 at 11:21 PM, Robert Gault <robert.gault at att.net> wrote:
> Adapting a 28-pin EPROM to a 24-pin Disk ROM socket is simple but a tight
> fit in some cases. I've done it with a low profile socket stuck into the
> controller socket with the EPROM plugged into the top of the stack.
>
> Take a low profile socket and bend out pin 20. Solder this pin (with a wire)
> to pin 22. Solder together pins 26, 27, & 28 connecting these pins to pin 1
> (with a wire). Solder a wire to pin 2 and plug the other end of the wire
> into pin 20 of the controller socket.
> Now plug the adapter into the controller socket so that pins 1,2,27, & 28
> don't go into the controller socket but pins 3-26 do insert. Now you can
> plug your EPROM into the adapter.
>
> Good for a 27C128 EPROM.
>
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