[Coco] 68764/68766 EPROMs

[Zippster]

Hey guys,

I received some PCBs back today from OSH Park and  assembled
an adapter.  They work great.  They fit perfectly on American CoCo2
motherboards and F boards, even D boards (barely).

Simple, cheap ECB ROM replacement for these machines.

- Ed

<https://drive.google.com/open?id=0B1sgl615FlGnUDRsa0J2ZVZwYkU <https://drive.google.com/open?id=0B1sgl615FlGnUDRsa0J2ZVZwYkU>>
<https://drive.google.com/open?id=0B1sgl615FlGnN0p3YTZxd0NtUEk <https://drive.google.com/open?id=0B1sgl615FlGnN0p3YTZxd0NtUEk>>
<https://drive.google.com/open?id=0B1sgl615FlGnRHVEMEhMcHlqSUE <https://drive.google.com/open?id=0B1sgl615FlGnRHVEMEhMcHlqSUE>>
<https://drive.google.com/open?id=0B1sgl615FlGneGNOQTNNOTB4RVU <https://drive.google.com/open?id=0B1sgl615FlGneGNOQTNNOTB4RVU>>


> On Sep 21, 2015, at 7:00 PM, Al Hartman <alhartman6 at optonline.net> wrote:
> 
> Very cool!
> 
> My burners will handle 68766 EPROMS, but being able to use a 2764 will help lots of folks.
> 
> Thanks for doing this!
> 
> -[ Al ]-
> 
> -----Original Message----- From: Zippster
> 
> I just started drawing an adapter up a few minutes ago.
> Cutting a deal for the proms to go with them.  They will be far less than $18.
> I have quite a few CoCos that could use an ECB, so it’s something I’ve been
> intending to do anyway.
> 
> I’ll should have files off to OSH Park tonight or tomorrow, there’s not much to an
> adapter like this.
> 
> - Ed
> 
> 
> 
>> On Sep 21, 2015, at 5:53 PM, Al Hartman <alhartman6 at optonline.net> wrote:
>> 
>> This is not for a disk controller. Ron needs an Extended BASIC ROM for a Coco he bought. I no longer have any masked ROMs, and offered to burn him one if he could get me the blank EPROMS.
>> 
>> But a 2764 with an adapter will cost as much as that 68766 for $18.00, unless Ron can wire one up himself.
>> 
>> Clearance isn't a problem for an ECB ROM.
>> 
>> -[ Al ]-
>> 
>> -----Original Message----- From: Arthur Flexser
>> 
>> P.S.  It is also possible to bypass the disk controller clearance problem
>> by having a 28-pin 2764 or 27128 EPROM in a 24-pin disk controller socket
>> with pins hanging off the end and other pins bent outward to not plug in,
>> hand-wiring a few connections between things.  Not pretty, but workable.
>> 
>> Art
>> 
>> On Mon, Sep 21, 2015 at 6:33 PM, Arthur Flexser <flexser at fiu.edu> wrote:
>> 
>>> There have been various such adapters in the CoCo and non-CoCo markets. I
>>> sold one with ADOS for a time.  Cloud 9 sells a particularly low-profile
>>> one, though it is somewhat more expensive than those sold by others. There
>>> is not quite enough clearance for most adapters in the Tandy disk
>>> controllers--some have tried cutting a hole in the plastic cover, or just
>>> living with the cover not quite being able to snap shut (the screw will
>>> keep the cover from coming off, and the controller can still be inserted in
>>> the cartridge slot.  Probably not great for the long haul to have pressure
>>> on the circuit board, though.)  The Disto controllers, with their sheet
>>> metal covers, have a bit more clearance.  The problem of clearance is
>>> greatly magnified if you want to piggyback a SmartWatch real-time clock
>>> underneath the Disk Basic ROM.  (I went with a cutting-a-hole-in-the-cover
>>> method there in my own CoCo system.)
>>> 
>>> A consideration that also exists is that it may be harder to find an EPROM
>>> programmer capable of programming the 6876x series than for the 27xx EPROMs.
>>> 
>>> Art
>>> 
>>> 
>>> On Mon, Sep 21, 2015 at 6:14 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
>>> 
>>>> Would it be more practical to make an adapter to plug in more common 27xx
>>>> series EPROMs? I don't recall how much physical clearance is in there.
>>>> 
>>>> --
>>>> Mark J. Blair, NF6X <nf6x at nf6x.net>
>>>> http://www.nf6x.net/
>>>> 
>>>> 
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>>>> 
>>> 
>>> 
>> 
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