[Techtoolslist] Data I/O Series 22 problem

[John Robertson]

On 04/30/2016 7:22 AM, vector wrote:
>
> Following up on my own post....
>
> I'm going to take a logic probe to it to check activity on the address 
> lines during a chip read.
>
> Hopefully looking at the schematics that the 4099 connected to that 
> socket pin is the culprit.
>
> I'm gathering that one bit at a time the address lines are latched, 
> and then the device would read or program.
>
> I just hope it is the 4099 and not one of the 'pin driver' modules.  
> Doubt those can be found anymore.
>
> Ebay seller says this works (it passes self test)... so far is not 
> willing to work with me on the issue.  His listing does indicate no 
> refunds, but then why list something as working ?  sigh.... I hope it 
> is that 4099.
>
> -- Curt

Hi Curt,

Can't help you with the Series 22, however are you aware of the large 
Data I/O mail list on Yahoo?

<*> To visit your group on the web, go to:
     http://groups.yahoo.com/group/Data_IO_EPROM/

The series 22 has been discussed there a number of times over the years 
I have belonged. There are about twenty or so people on the list with 
that device in their collection.

John :-#)#
>
> On 2016-04-29 16:39, vector wrote:
>> I purchased a Series 22.... and now that I've ruined 6 Harris 7641
>> equivalent PROMs (minimum value about $15)... I've determined what the
>> symptoms are I am seeing.
>>
>> This is a 512 byte PROM.
>>
>> I'm thinking A6 line to the PROM during read is either high or
>> floating, as if you break the 512 byte range into 8 blocks of 64 bytes
>> you should have
>>
>> ABCDEFGH
>>
>> When I read a good source rom in, I use edit and compare it against a
>> known good hex dump, and I'm seeing
>>
>> BBDDFFHH
>>
>> with blocks A, C, E, and G missing.
>>
>> This would seem to idnicate that the A6 line is high during read.
>>
>> Unfortunately my MOD-EMUP which should handle these PROMs 49 times
>> out of 50 (or so it seems) will read any 7641 or compatible as all FFs
>> (which it probably ins't reading anything... and the FFs were part of
>> the EMUP's software clear).
>>
>> I think I read you can read these as a 2732 and the 512 bytes ends up
>> repeated I think in specific positions in the read.... I have to
>> google that again to see if during the writes, the A,C,E,and G blocks
>> are all 0 still like on a blank PROM.
>>
>> I'm going to strip it down to look at the boards... and check first
>> at the socket.
>>
>> If that line is floating will I get this behavior, or only if it is
>> driven high ?
>>
>> Thanks,
>>
>> -- Curt
>>
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