Re: Saturn 128k Problems

[Hugh Hood <hughhood@earthlink.net>]

Steve:

If you'd like to troubleshoot the Texas 'shade tree' way, I'll be happy to
send you a loaner card.

Just swap parts until you find the culprit, and then order a replacement
chip.

I _think_ every component on the Saturn board is socketed, BTW.

If you're interested, give me a few days to find the loaner board and test
it with Robo. (I scrapped all my II+'s years ago after removing the power
supplies, so I'll bet the Saturn test program will not help me).

I'd better test the card first though, as I purchased a Saturn board a while
back on eBay and it didn't work. You wouldn't want that to pull chips from
that one.

Are you still in New England?





Hugh Hood




in article SrWdnRJ52usQpFPSnZ2dnUVZ_t6dnZ2d@giganews.com, Steven Hirsch at
snhirsch@gmail.com wrote on 6/5/12 11:53 AM:
>>> 
>>> I cannot reproduce that, leading me to believe that I do have a problem with
>>> the Saturn board.  I'm going to try swapping out some of the LS TTL logic
>>> for newer parts and see if I can get it to behave.
>>> 
>>> Would still be great if someone had the schematic.
>>> 
>>> 
>> I recall that it used that pair of Motorola ICs designed for controlling
>> dynamic ram, one is a multiplexer the other is a controller.  Large multipin
>> ICs, and they should jump out when you look at the board.  There should be a
>> datasheet or application note devoted to those ICs, and I suspect the board
>> can't be much different from that "typical design". That would make a good
>> start to a schematic, the interface to the bus can't be too complicated.
> 
> Actually, only a single large-package part: MC3242AP.  But, that's a good
> suggestion.  I'll see if I can chase up any data sheets.
>