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Looking for a working 835 modem...


35 replies to this topic

#1 DavidMil OFFLINE  

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Posted Wed Dec 14, 2016 4:18 PM

Any body have a working 835 modem (in the USA) that they are willing to sell/rent/loan me for a few weeks?  I need to make a copy of the

1k ROM on the MPU so I can fix a couple of others I have.  I don't mind sending a security deposit for the use of the modem too.

Or if someone knows where I could find a working 835 please let me know!

 

Thanks,

David Milsop

Kingwood,  Texas



#2 _The Doctor__ OFFLINE  

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Posted Wed Dec 14, 2016 6:14 PM

failing that can someone make a copy for you, might be an option?



#3 David_P OFFLINE  

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Posted Thu Dec 15, 2016 6:01 AM

Perhaps Best or B&C have the ROM for sale?

#4 DavidMil OFFLINE  

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Posted Thu Dec 15, 2016 6:40 PM

I've talked to Brad at Best and he said they are totally sold out.  B&C doesn't have one listed, but I haven't talked to anyone there

yet.  I would be pleased and willing to pay someone for an image of the 1K of ROM that the 8048 had.  The thing is, Atari used this chip in other  

devices as well.  I know for sure that the 1027 had one.  So the chip has to come out of an 835.

 

DavidMil



#5 David_P OFFLINE  

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Posted Thu Dec 15, 2016 11:04 PM

What is the Atari part #?



#6 BillC OFFLINE  

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Posted Fri Dec 16, 2016 3:58 AM

The Best Electronics website does list the MPU for the 835(under custom ICs), but you would need to confirm with Brad if it contains the proper firmware.

 

CO60549       (835 MPU)       $15.00



#7 tuf OFFLINE  

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Posted Sat Dec 17, 2016 4:22 AM

The Best Electronics website does list the MPU for the 835(under custom ICs), but you would need to confirm with Brad if it contains the proper firmware.

 

CO60549       (835 MPU)       $15.00

 

I have an 835 and Dropcheck's ROM burner - if that can handle it I'll dump it for you.



#8 DavidMil OFFLINE  

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Posted Sun Dec 18, 2016 1:37 AM

That would be really cool! 

 

Thank you,

David Milsop

Kingwood,  Texas



#9 BillC OFFLINE  

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Posted Sun Dec 18, 2016 7:25 PM

According to the 835 schematic there is no separate ROM, there would only be the 1kB ROM integrated into the 8048 MPU.



#10 DavidMil OFFLINE  

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Posted Sun Dec 18, 2016 7:56 PM

That is correct.  The 1k Rom is on the P8048H chip.

 

David



#11 gamer-stu OFFLINE  

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Posted Thu Jan 5, 2017 8:16 PM

I have one that I could send you, if you're still looking. For free (minus power supply). I can't test it, but the light turns on when I flick the power switch. 😀

#12 DavidMil OFFLINE  

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Posted Mon Jan 9, 2017 7:56 PM

I got the 835 board and I'll test it out tonight.  Is there something I can help you with?

 

Thanks again,

David Milsop



#13 gamer-stu OFFLINE  

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Posted Mon Jan 9, 2017 8:12 PM

Glad you got it. Might be good to upload the rom to archive.org or some other repository.

#14 DavidMil OFFLINE  

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Posted Thu Feb 23, 2017 11:10 PM

I got a good P8048 MPU chip and I now have two working 835 modems and I fixed gamer-stu's modem too.  I tested them with Atari's CPS Diagnostic Disk FD100577 (Rev 02).

 

Thanks to all!

David Milsop

Kingwood,  Texas



#15 ijor OFFLINE  

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Posted Fri Feb 24, 2017 4:55 AM

Please share the ROM dump so that it could be publicly preserved. Thanks.


Edited by ijor, Fri Feb 24, 2017 4:55 AM.


#16 Kyle22 OFFLINE  

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Posted Fri Feb 24, 2017 10:52 AM

I have a Universal Programmer that does 8048's if you're interested.

 

Hopefully, it isn't copy protected.



#17 AtariGeezer OFFLINE  

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Posted Fri Feb 24, 2017 4:59 PM

I got a good P8048 MPU chip and I now have two working 835 modems and I fixed gamer-stu's modem too.  I tested them with Atari's CPS Diagnostic Disk FD100577 (Rev 02).

 

Thanks to all!

David Milsop

Kingwood,  Texas

Please post a dump of the ROM,  I have two that need fixing too :)

 

I have a Universal Programmer that does 8048's if you're interested.

 

Hopefully, it isn't copy protected.

Which Programmer is that?  My Willem will do P8048AH,  not sure if that is the same type of MCS?



#18 Bryan OFFLINE  

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Posted Fri Feb 24, 2017 5:06 PM

Yeah, we need to dump all the Atari 8048 code. I'm pretty sure there's info online for dumping even the protected ones.



#19 Kyle22 OFFLINE  

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Posted Fri Feb 24, 2017 5:59 PM

Please post a dump of the ROM,  I have two that need fixing too :)

 

Which Programmer is that?  My Willem will do P8048AH,  not sure if that is the same type of MCS?

I'll have to double check, but I believe my Sunrise Z-1000b will do them.



#20 DavidMil OFFLINE  

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Posted Fri Feb 24, 2017 11:20 PM

Please remember that the 8048 is not a ROM chip it is a MPU with 1K of ROM built into it.  I would doubt very seriously that you could copy protect it.

The ROM was dumped to a D8748 EPROM (which is a pin for pin compatible version of the 8048 MPU chip).   

 

David



#21 Kyle22 OFFLINE  

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Posted Sat Feb 25, 2017 12:12 AM

I know what an 8048 is, just wasn't sure if it supported protection.  Protection goes back to at least PALs



#22 ijor OFFLINE  

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Posted Sat Feb 25, 2017 9:27 AM

Seems there is no protection support on the 8048. But many MCU devices support firmware protection. Some based on masked ROM don't have any kind of external bus interface, other than I/O ports. So you simply have no external way to access the firmware. Other devices, usually using OTP (One Time Prom), have a firmware that could be written externally, but it couldn't be read back. I don't remember when the first devices with firmware protection by design were available.


Edited by ijor, Sat Feb 25, 2017 9:27 AM.


#23 _The Doctor__ OFFLINE  

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Posted Mon Feb 27, 2017 1:50 AM

Kyle should be able to read it and write it.... so it would be cool to let him do it... the resulting post should include not only the code but maybe a side note on what programmers/requirements that will write it for the future



#24 Kyle22 OFFLINE  

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Posted Mon Feb 27, 2017 1:01 PM

Well, I thought my Sunrise programmer did 8048's, but I got it out and fired it up, and no 8048's on the list.

 

I'm going to look for one that does them.



#25 AtariGeezer OFFLINE  

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Posted Mon Feb 27, 2017 1:56 PM

Yesterday I ordered a 8048 adapter for my Willem board from This Place  for only $4 plus shipping

 

I'll be able to read them, plus burn them :)   I'll post the dump as soon as the adapter arrives...

DavidMil  will not be able to post the ROM dump of the 835 as someone who donated a 8048 for him to check out doesn't want to share it (the ROM Dump)  :?


Edited by AtariGeezer, Mon Feb 27, 2017 1:59 PM.





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