[Coco] Extended Basic Upgrade Options

[Dave Philipsen]

Yes, but that's only a 32k-bit EPROM which means it's 4K-byte and not 
large enough for the BASIC ROM in a CoCo.

The problem is that whoever designed the CoCo decided to use the 68764 
pinout for the ROMs which is different from the defacto industry 
standard 2764.  Apparently Commodore used this ROM in the C64 as well.

Dave Philipsen


On 4/7/2015 12:13 PM, camillus blockx wrote:
> Hi Dave,
>
> I found this on Ebay, makes $1.33 a piece, which is good, most are over $3...
>
> The thing is 50 is a lot, but I would take 5 of you for 1.33 ( + shipping) if that would help. They always come handy, sometimes they can be used as PAL/GAL ( simple logic ).
>
> Hope it helps you, otherwise follow K.Koon's advice...
>
> http://www.ebay.com/itm/50PC-ST-M2732A-2F1-2732A-DIP-24PIN-IC-A236/181594062783?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3D7c903d0029f144d5925f197b122317a0%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D361262953848&rt=nc
>
> camillus
> On 4/7/2015 11:36:44 AM, Dave Philipsen <dave at davebiz.com> wrote:
> http://www.ebay.com/itm/MCM68764C-Semiconductor-Electronic-Component-/171739050313?pt=LH_DefaultDomain_3&hash=item27fc71f149
>
> On 4/7/2015 10:59 AM, Joe Grubbs wrote:
>> DIP-24 8Kx8s seem to be as rare as hens teeth. I have NOS ones that I'm saving for... whatever. Does anyone know of a decent source for the 24 pin variety or are we stuck with 28s nowadays?
>>
>>
>>> From: computerdoc at sc.rr.com
>>> To: coco at maltedmedia.com
>>> Date: Tue, 7 Apr 2015 00:12:47 -0400
>>> Subject: Re: [Coco] Extended Basic Upgrade Options
>>>
>>> Hi Don,
>>> I have a 24-pin rom/eprom to 28-pin 2764 eprom adapter PCB I designed that could give you the capability of using 28-pin eproms inside your Coco 2. Is there a 26-3027 Coco 2 or is it a 26-3127 Coco 2? If so, I have a 26-3127 I can use to check for layout correctness. I had made it to adapt the 24 pin rom socket in my floppy controllers to accept 28 pin 2764 eproms, but until now I have not needed to use it to adapt rom sockets on CoCo motherboards. I'm on vacation at the moment, but when I get back home Sunday, I'll check it out for you. I can provide the Extended Basic 1.1 rom you need also. I thought you might what to know.
>>>
>>> Kip Koon
>>> computerdoc at sc.rr.com
>>> http://www.cocopedia.com/wiki/index.php/Kip_Koon
>>>
>>>
>>
>
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