[Coco] Pardon me for asking...

[Charles Hudson]

Well, the ROMs are another story, one where the tail wags the dog:  I 
have some other TRS hardware and a few years ago bought a Tandy Color 
Disk Drive thinking I could adapt it for use with a Model III.  Later I 
acquired a 26-3022 controller to drive it. Then I read that the 
controller needed 12VDC and that the CoCo 1 provided it, so I bought the 
CoCo.  It got damaged in shipping so I broke the seal and took it apart 
to repair the case.  While it was open I inventoried and found I had 
Color BASIC 1.1, no ECBASIC, and a 16k E board.  And video so shaky it 
makes you itchy just to look at it.  And the drive didn't respond.

I found I needed CB1.2 and ECB ROMs to talk to the drive.  No problem: I 
had EPROMS and EPROM burners, but then I found that the recommended 
EPROM, an MCM68766, required 25 VDC to program; a voltage my USB burners 
could not furnish.  I looked at adapter boards but decided against them 
because they interfered with the other components and prevented 
re-installation of the RF shield. I found a Needham's programmer on eBay 
but am still collecting the pieces for that, so I sent two blank ROMs to 
Cloud-9 for programming.

I still don't know if the damned TCDD is operational, but at least I 
have a CoCo to show for it, replete with 64K RAM and an Hitachi CPU.  
Keyboard is funky and the video is awful but we'll get to that, I suppose..

-CH-

On 12/14/2021 11:46 AM, Dave Philipsen wrote:
> What’s really cool about this is that with the mod to access the full 64k you can actually load the Extended BASIC ROM in from cassette! My very first CoCo had only 4K and Color BASIC. I did the 64k upgrade with chips that at the time cost me $50.  But then, before I built my own EPROM programmer I was able to do that to get Extended BASIC.
>
>
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>> On Dec 14, 2021, at 7:53 AM, Charles Hudson <charles484 at twc.com> wrote:
>>
>> I completed the procedure up to the point of performing the 64k addressing modification; in other words, "PRINT MEM" now shows 31015.  As I don't have OS-9 or any way to load it I will wait until the updated ROMs arrive to modify further.
>>
>> Thank you again for your assistance.
>>
>> -CH-
>>
>>> On 12/8/2021 6:47 AM, Charles Hudson wrote:
>>> Thank you Mr. Boyle for your suggestion.  I will follow the procedure outlined in Rainbow magazine, of which I was unaware.
>>>
>>> -CH-
>>>
>>>> On 12/6/2021 4:39 PM, L. Curtis Boyle wrote:
>>>> Yes, that would be an “E” board, which officially supported 32K of RAM (and the jumpers should be labelled 4K, 16K, 32K - move them all to 32). With slight modifications, it will support the full 64K of RAM as well.
>>>>
>>>> You can find the details here: https://colorcomputerarchive.com/repo/Documents/Magazines/Rainbow,%20The%20(OCR)/The%20Rainbow%20Vol.%2003%20No.%2010%20-%20May%201984.pdf
>>>> (go to page 50, where it says “E Board” under the “All the Way to 64K”).
>>>>
>>>>
>>>>
>>>>> On Dec 6, 2021, at 5:40 AM, Charles Hudson <charles484 at twc.com> wrote:
>>>>>
>>>>> Mr. Boyle asked:
>>>>>
>>>>> "Do you know which version of the motherboard that you have (C,D,E, F (285))? That will make a difference on jumper settings and whether you have to do more than just move jumpers."
>>>>>
>>>>> The board is screened with "8709137-E" on the component side near the cartridge bay, which I suppose to mean it is a revision E board.
>>>>>
>>>>> -CH-
>>>>>
>>>>> ____________________________________________
>>>>>
>>>>> Do you know which version of the motherboard that you have (C,D,E, F (285))? That will make a difference on jumper settings and whether you have to do more than just move jumpers.
>>>>>
>>>>> Sent from my iPhone
>>>>>
>>>>> On Dec 5, 2021, at 4:40 PM, Charles Hudson<charles484 at twc.com>  wrote:
>>>>>
>>>>> I have owned a Color Computer Model 1, catalog 26-3004, for about two months.  It came to me as a 16k machine with Basic 1.1 in ROM..  I already had a Color Computer Disk Drive and the interface card and wanted the machine to drive them.
>>>>>
>>>>> For these weeks I have been reading the mailing list but this is my first post here.  I soon discovered that I needed to replace the 1.1 ROM and add Extended Color Basic for the purpose or communicating with the drive.  I also read that it was possible to exchange the CPU for an Hitachi and to replace the 4116 RAM with 4164.
>>>>>
>>>>> I'm working on the ROM replacements; that's not completed yet.  I have replaced the CPU and the RAM, and the machine boots to the Tandy Basic 1.1 prompt, but when I issue the "PRINT MEM" command the result is about 14k.
>>>>>
>>>>> Without going into long detail let me say I'm pretty sure I have the jumpers set wrong.  I'm writing to ask if anyone can point me to the correct configuration.  Thank you for your replies.
>>>>>
>>>>> -CH-
>>>>>
>>>>> -- 
>>>>> Coco mailing list
>>>>> Coco at maltedmedia.com
>>>>> https://pairlist5.pair.net/mailman/listinfo/coco
>>>>>
>> -- 
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