Date   : Fri, 05 Jun 2009 16:07:46 +0100
From   : acorn@... (Andy Ford)
Subject: Issue 4 will not accept a 1770

Thanks for the quick reply :)

Yes, this was the first thing I did (cut the wire link at S9) , tested 
after I cut it actually to ensure it was definitely open.

I did actually mention this in my first composed email, but Thunderbird 
crashed before I could submit it, so I had to redo another one, must of 
left that line out of the things I have done by mistake.


Andy.



michael.firth@... wrote:
> You have removed the NMI link (I think its S9) haven't you (it doesn't
mention this in your message)?
>
> Regards
>
> Michael 
>
>   
>> -----Original Message-----
>> From: 
>> bbc-micro-bounces+michael.firth=bt.com@... 
>> [mailto:bbc-micro-bounces+michael.firth=bt.com@...
>> .uk] On Behalf Of Andy Ford
>> Sent: 05 June 2009 15:51
>> To: bbc-micro@...
>> Subject: [BBC-Micro] Issue 4 will not accept a 1770
>>
>> Hello.
>>
>> Just a bit of advice really :)
>>
>> I have here an Issue 4 'B. As far as I am "aware" , this has 
>> always been 
>> a tape only machine. However, I am unable to get a 1770 based DFS to 
>> work in it. It's simply completely ignored.
>>
>> To confirm a few things first.
>>
>> The parts I am using (I have tried two different sets, one by 
>> WE and one 
>> by RetroClinic) , both kits function and are 100% ok in 
>> another machine. 
>> It's just this particular Issue 4 that does not seem to like 
>> it for some 
>> reason. As I say, all the kit parts do work in another machine.
>>
>> IC86 = Fitted a link
>> IC87 = Fitted a link (as an extra note I did have a spare 
>> 74LS123 that I 
>> tried as part of my "testing" too)
>> IC79 + IC80 = Fitted 7438's (tried the ones from the WE machine too)
>>
>> The other links are set as follows (have not touched them)
>>
>> S18-North
>> S19-East
>> S20-North
>> S21-2 x East/West
>> S22-North
>> S32-West
>> S33-West
>>
>> I do not have enough spares lying around to try a 8271 based 
>> interface 
>> at the moment (yet) although I really only want the 1770 kit to work. 
>> Yes, I did fit the ROM and the module (as I say, I have two kits and 
>> have tried each component in another machine and it all works 
>> fine) , I 
>> traced a few of the pins of IC78 and they seemed ok.
>>
>> It was suggested to me to replace the 7438 on the far left 
>> side ( thanks 
>> Mark :) ), this I did yesterday evening (after cursing Acorn for not 
>> fitting a socket here, I have done) , although it's no better (I made 
>> sure the socket I fitted was fine regarding continuity etc)
>>
>> Just wondered what the next sensible thing to test / replace would be 
>> really. I have a multimeter but I do not have an oscilloscope so can 
>> check a few things if directed. I do have a machine on its 
>> way here via 
>> Ebay to put this kit into but I'd rather not have this 
>> machine in this 
>> kind of "limbo" state if possible.
>>
>>
>> Thanks :)
>>
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>> http://lists.cloud9.co.uk/mailman/listinfo/bbc-micro
>>
>>     
>
>