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Looking for a working 835 modem...


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#26 gamer-stu OFFLINE  

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Posted Mon Feb 27, 2017 8:59 PM

That's too bad. Unfortunately it wasn't my MPU that worked; I would have gladly shared it. It turns out that the 835 that I donated had a bad MPU, but David repaired for me. Thanks David!

#27 Stephen OFFLINE  

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Posted Mon Feb 27, 2017 9:21 PM

Silly me - I just noticed I have an 835 sitting next to me in my Atari pile.  Thought it was an extra 850.  I do not know if it works, but I will try to find out ASAP.  I may not have a device capable of reading the 8048 - if not I'll buy one if it's not too much.

 

EDIT

Doesn't look like it's possible to read those chips with the TLC-866.  Any suggestions?



#28 DavidMil OFFLINE  

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Posted Wed Mar 1, 2017 12:03 PM

That's too bad. Unfortunately it wasn't my MPU that worked; I would have gladly shared it. It turns out that the 835 that I donated had a bad MPU, but David repaired for me. Thanks David!

 

Mailing your board back to you today.  I'll send you the info when I get back from the post office.

 

David



#29 AtariGeezer OFFLINE  

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Posted Sat Mar 11, 2017 3:52 PM

The MCS-48 adapter arrived in the mail yesterday and today I was able to read the P8048AH chips from 3 of my 835's.

Two read totally BLANK and the working 835 read results appear to have been read good :)

 

Check it out:  Attached File  835 (ATARIGEEZER).ROM   1KB   20 downloads



#30 DavidMil OFFLINE  

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Posted Sun Mar 12, 2017 1:09 AM

The MCS-48 adapter arrived in the mail yesterday and today I was able to read the P8048AH chips from 3 of my 835's.

Two read totally BLANK and the working 835 read results appear to have been read good :)

 

Check it out:  attachicon.gif835 (AtariGeezer).ROM

 

Very cool!  Will the adapter allow you to burn an 8048 or an EPROM also?

 

David



#31 AtariGeezer OFFLINE  

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Posted Sun Mar 12, 2017 11:46 AM

Very cool!  Will the adapter allow you to burn an 8048 or an EPROM also?

 

David

Yep,  it's supposed to :)  I'll be buying some D8748H's and P8748H's  to test  soon...



#32 DavidMil OFFLINE  

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Posted Sun Mar 12, 2017 1:28 PM

Yep,  it's supposed to :)  I'll be buying some D8748H's and P8748H's  to test  soon...

 

Do you know if it will do D8049HC's also?  I believe that this is just a 8048 with 2K of ROM.  Atari used this chip in some of their

other printers.

 

David Milsop



#33 AtariGeezer OFFLINE  

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Posted Sun Mar 12, 2017 1:49 PM

Do you know if it will do D8049HC's also?  I believe that this is just a 8048 with 2K of ROM.  Atari used this chip in some of their

other printers.

 

David Milsop

If you mean the  D8749H (EPROM)  or  P8749H (One Time Prrogram)  types with 2k of programmable memory  then yes...



#34 DavidMil OFFLINE  

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Posted Sun Mar 12, 2017 4:31 PM

If you mean the  D8749H (EPROM)  or  P8749H (One Time Prrogram)  types with 2k of programmable memory  then yes...

 

I guess if it will burn a 8749 it will surely read a 8049.  This is good to know and very cool.

 

David Milsop



#35 AtariGeezer OFFLINE  

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Posted Sat Mar 18, 2017 10:05 PM

After looking at Jerzys'  835 Schematic,  I noticed a few errors like missing components,  missing traces and  wrong pin assignments.  I  compared it to the FSM Schematic and actual 835 Circuit Board  and decided to rework it.

 

This it what I came up with:

Atari 835 (Geezer).gif



#36 DavidMil OFFLINE  

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Posted Sun Mar 19, 2017 4:32 PM

Here is something to complement your schematic:

Attached Files






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