[Coco] Eproms

[Arthur Flexser]

The most prized EPROM for the CoCo would probably be the 68766, an 8K,
24-pin chip that was compatible with all the ROM sockets of the original
CoCo and Tandy disk controllers (except the FD502).  Very hard to obtain
nowadays, I believe.  (A slower version, the 68764, also exists and
probably works okay in the CoCo.)

Art

On Fri, Feb 15, 2013 at 1:52 PM, Mathew Boytim <maboytim at yahoo.com> wrote:

> Hi John,
>
> Thanks for the reply but I think your numbering is off - a 27C64 would be
> 64 kbit in an 8kx8 configuration.  27C32 would be 32 kbit in 4kx8.
>
> The transition from 24 pins to 28 pins usually occurs between 2732 and
> 2764 (4k and 8k).  The Model 1 w/ Level 2 Basic has 12k bytes of ROM.  At
> least the early one that I had had two ROM's - one 8k, one 4k, both were in
> 24 pin packages - and both on a satellite board that was connected to the
> mainboard by a ribbon cable an a few wires.  I think there was like a 2564
> that was kinda rare but it was an 8k in a 24 pin package.  I think it was
> more convenient to replace the 8k ROM with a 2564 if you could find one.  I
> think eventually I replaced both ROM's and the satellite board with a
> single 16k EPROM and a few skywires.
>
> I didn't know if there was a particular EPROM that worked out best in the
> Coco.  I'm more of a model 1/3 enthusiast but a friend clued me into the
> Coco mailing list and I've been monitoring some of the discussions.
>
> Thanks again,
>
> Matt
>
> --- On Fri, 2/15/13, John Donaldson <johnadonaldson at sbcglobal.net> wrote:
>
>
> From: John Donaldson <johnadonaldson at sbcglobal.net>
> Subject: Re: [Coco] Eproms
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Date: Friday, February 15, 2013, 11:15 AM
>
>
> If you talking 8K EPROMS then  something along the line of a 27C010 which
> is a
> 8KX8 (64K) EPROM. These are the same size as the Basic ROMS.
> IIRC   a 27C512 EPROM is a 4KX8 (32K) EPROM which may be the smallest you
> want
> to go with.
>
> JohnD.
>
>
>
>
> ________________________________
> From: Mathew Boytim <maboytim at yahoo.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Fri, February 15, 2013 10:19:17 AM
> Subject: Re: [Coco] Eproms
>
> Which EPROMs are desirable for the coco?  I used to have stacks of EPROMs
> but
> when younger my daughter would make stuff with them and the antistatic
> foam and
> they got bent and damaged but I didn't care - and eventually pitched
> them.  I
> still have a small assortment though.
>
> Matt
>
> --- On Fri, 2/15/13, John Donaldson <johnadonaldson at sbcglobal.net> wrote:
>
>
> From: John Donaldson <johnadonaldson at sbcglobal.net>
> Subject: Re: [Coco] Eproms
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Date: Friday, February 15, 2013, 8:02 AM
>
>
> Sorry Luis, but I am all out of EPROMS.
>
> JohnD
>
>
>
>
> ________________________________
> From: Luis Fernández <luis46coco at hotmail.com>
> To: COCO <coco at maltedmedia.com>
> Sent: Thu, February 14, 2013 10:22:38 PM
> Subject: Re: [Coco] Eproms
>
> Hi John Donaldson
>
> Still have eprom?
> I would like to change my controller to 28 pin and still use your eprom
>
>
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