[Coco] Dual UART with FIFO Card for the CoCo

[Gene Heskett]

On Sunday 13 June 2010, sales at gimechip.com wrote:
>Gene,
>I mapped the UARTS at $FF50-$FF5F - I split SCS* in half and passed
>$FF40-$FF4F out to a feed-thru cartridge connector for the disk controller
>to plug into and I used $FF5x for the two UARTS.

Mmmm, that I think will interfere with the real time clock chips in many of 
our disk controllers.  Most of them are in the $FF50-5F range by way of 
additional decoding in the controller.  Some are a bit portable, iirc I can 
put the clock in my TC^3 controller in the high block of $FF7x by jumpers.  
The various other scsi/ide drive interfaces do something similar, but I 
should defer to Mark Marlette and GCCC for fresh definitions on that as I 
don't have that hardware.

One thing that rather fell by the wayside was that at one point Tandy tried 
to set std addresses for this and that, then didn't stick to it at all well, 
probably because there were quickly more aftermarket devices than they 
imagined there would be.

In any event, this has been a PIMA for me for 20 some years, and I have more 
than once run through my 5 minute monolog of swear words directed at Tandy 
because Tandy didn't fully decode their own crap.  Friggin bean counters 
will be the death of the engineering profession yet. :(

>I need to go look at the Datasheets - you've got me wondering if I
>overlooked something - I think the 16550 only needs 8 addresses, but I
>better check... just checked - yep just 8 addresses...
>whew :-)
>
>-John
>
>
>----- Original Message -----
>From: "Gene Heskett" <gene.heskett at gmail.com>
>To: <coco at maltedmedia.com>
>Sent: Sunday, June 13, 2010 5:37 PM
>Subject: Re: [Coco] Dual UART with FIFO Card for the CoCo
>
>> On Sunday 13 June 2010, sales at gimechip.com wrote:
>>>On CoCo3.com, I asked for project ideas and requests. One request was
>>> for a Dual UART card w/FIFO. I thought this would be a good one, so I
>>> spent yesterday studying the datasheets and then, this morning I
>>> created a preliminary design using E.A.G.L.E. The complete project is
>>> now posted here:
>>> http://www.coco3.com/community/2010/06/a-dual-uart-with-fifo-card-for-t
>>>he -coco Let me know if you spot any potential problems with the design.
>>> Thanks - John
>>
>> The only problem I see is the additional i/o addresses it needs.  8 per
>> chip
>> sure beats the original 16450's 16 per chip, but with the coco's very
>> limited I/o mapping, at least in os9, finding that space is going to be
>> fun.
>>
>> In my own situation, I do have a dual port ACIA, addressed adjacent to
>> each
>> other from FF64 to FF6B (iirc), which meant I had to hack Rogers BT pack
>> to
>> use FF60-63.
>>
>> I would like to ask how much trouble it would be if we could figure out
>> a way to isolate the first $40 of page $FF by more fully decoding the
>> two PIA's it uses, so they would not see a /cs except at $FF00-03, and
>> $FF20-23.
>>
>> That would clear out and make usable a considerable amount of i/o
>> address space, allowing this to be addressed at $FF10-1F for instance. 
>> That would still leave room for 6 more 4 bit wide devices.
>>
>> So basically, we first need a kit that will fix all of our coco's,
>> freeing up this very sorely need i/o space.
>>
>> I looked at that myself but about 2 decades ago, so any ideas I may have
>> had
>> then are moot now.  And I of course am not the least bit allergic to
>> plugging in my iron and fixing it as long as I can adequately see what
>> I'm doing.  Diabetes is trying to fix that for me now.  But, I'm still a
>> C.E.T.,
>> so I'd be willing to be a test site, I have more than 1 coco3 here.
>>
>>
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> http://five.pairlist.net/mailman/listinfo/coco
>
>--------------------------------------------------------------------------
>------
>
>
>
>No virus found in this incoming message.
>Checked by AVG - www.avg.com
>Version: 9.0.829 / Virus Database: 271.1.1/2934 - Release Date: 06/13/10
>01:35:00
>
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco
>


-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Don't look now, but the man in the moon is laughing at you.