[Coco] Grant Searles SBC

Zippster zippster278 at gmail.com
Wed May 6 21:18:40 EDT 2015

That was my first thought, the clock to the ACIA, I’ve seen that problem before (on a totally different system).

Running a different ACIA with it’s own oscillator might be a good idea.

- Ed

> On May 6, 2015, at 8:02 PM, Bill Nobel <b_nobel at hotmail.com> wrote:
> No Prob Kip, I realize you are a busy man.  I am using a AH0267RF FTDI I got for $5.00 from E-Bay works well on everything I tried except the SBC.  I am thinking I have a slight clock problem to the 68B50.  My frequency counter doesn’t have a fine enough scale to show if I actually have 1.8432 (only shows 1.843) so I could be off by a couple of hertz.  Unfortunatly i don’t yet have a scope but I am looking at a Hantek system for my PC, then I could verify some other things.  I am also looking to source some 6551 ACIA’s as well the have a baud rate generate built in that use a 1.8432 mhz crystal.  This is the chip that is used in the RS-232 pak from the shack back in the day and I have used them in the past with great success.
> Bill Nobel
>> On May 6, 2015, at 6:47 PM, Kip Koon <computerdoc at sc.rr.com> wrote:
>> Hi Bill,
>> I apologize for not being on the email list lately.  Being back home, I've had to take care of life issues as well as play just a little bit with my new toy.  :)  I'll be glad to help you.  I've had similar problems when I breadboarded Grant's 6 Chip 6809 Computer (Simple6809) 4 years ago, so I have a pretty good idea of the anguish, blood, sweat and tears it takes to learn digital circuits on your own.  :)  Fortunately for me, everything was running properly except the serial port when I did it.  
>> Since then however, I have acquired an FTDI 24 pin footprint PCB version of their USB chip which I too would eventually like to use.  Then I could have an additional choice for future versions of the Kipper SBC.  
>> By the way, which FTDI chip or PCB are you trying to use?  
>> Keep in touch.  We all will help you figure this thing out!  Have Fun!  Take care my friend.
>> Kip Koon
>> computerdoc at sc.rr.com
>> http://www.cocopedia.com/wiki/index.php/Kip_Koon
>>> -----Original Message-----
>>> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Bill Nobel
>>> Sent: Wednesday, May 06, 2015 7:16 PM
>>> To: CoCoList for Color Computer Enthusiasts
>>> Subject: [Coco] Grant Searles SBC
>>> Hi guys.  This is a shout out to the Hardware Experts out there.  I am trying to build this unit on a breadboard and am having some
>>> issues.  I am following the circuit to a tee.  Powering up I get 1.843 mhz on the E & Q lines R/W is working.  But sometimes when I hit
>>> reset my BA line goes high throwing CPU into HALT state even though my HALT is tied High.  Also on the terminal window I am getting
>>> nothing but garbage @ 115200 baud.  The one difference to the circuit I am using a FTDI instead of the 9 pin serial plug.  I verified the
>>> FTDI by connecting to a old desktop pc using Hyperterm so the chip is working.  But on the SBC I get nothing.  I even went to the
>>> extent of swapping out all the chips and verified by hand the Eprom code to see if it Burned properly.
>>> Any suggestions or help would be appreciated.
>>> Bill Nobel
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