Re: Finally got a SIO2PC, have a question for anyone who has one?

Slor wrote:
> Despite all prevention efforts, stephensheppard@xxxxxxxxxxx wrote in
> news:1137190317.958081.57800@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:
>
> >
> > - Steve Sheppard
> >
>
> Heya Steve - You got that machine all working yet?
>
> --
> James
> http://www.slornet.com

800XL works but but 3.5 mods out of 5 don't.

1) Clear picture mod still has weird leading edge colors but picture is
very sharp.

2) Internal SIO2PC works great. I love modular RJ11 cable, light
weight, long lengths possible, and doesn't fall out (unlike those darn
SIO connectors).

Finally bought off-the-shelf RJ11/DB-9 female adapters $1.89 each
(something like that). Now I can plug the RJ11 cable into any of my
PCs not just the one.

LOL spent about half an hour trying to figure out the pinouts I used.
RJ11 is *** end to *** end. It's straight thru but pins 1-4 become
4-1 at the other end so remembering Send/Receive, ground, and Command
line in the Atari connect to which solder joints on the RJ11 connector,
connects to which pins inside the moudlar connector, maps to what pins
at the other end, maps what RS232 pins. Well, that was all an ordeal.
I never write things down.

I should have built a Max233 interface (like my external one). The
1-chip 14C89 SIO2PC works but I forgot it's not compatible with my
ATR8000 (dumb mistake). Further I can't even connect the external
Max233 interface and use that to talk to the ATR8000. Well, I don't
use it much and I still have the 800.

I did find it amusing that I can use both the internal SIO2PC and the
external one and talk two different PCs. Can't say I have a practical
reason to do this.

3) I botched the Wizztronics 256K upgrade. I've got one of the 800XL
models that requires two extra ICs for the Wizztronics. Problem was
all the mounting holes on the Wizztronics board were filled with
solder. I tried to remove it without the proper tools and did a poor
job. Put the chips in anyway but they were only half in. Needless to
say the board doesn't work.

4). Homebrew MyIDE still doesn't work yet. Originally it would
properly detect only 1 drive out of the 4 spares I have but that drive
had 20+ errors so I couldn't really use it. Mr Atari suggested I
replace the 74HCT ICs with 74F types but now I have 33% errors on that
drive and MyIDE gets random data for Cylinder/Head/Sector information.
The old partitions (and new ones) are still there but I can't access
them.

Right now I'm wondering if a CompactFlash is more tolerant of the
timing problems.

4) Bob Woolley's SmartOS is going equally badly. I should never have
stuck with the original plan and not try to scale it down since I don't
read schematics very well as it is.

First I planned to piggback the SRAM over OS ROM but I was waiting for
a friend to burn some backup EPROMs for me. He was busy so I scaled
the project back to doing just the internal cartridge. I put a 28 pin
socket in the stock 24 pin socket and pulled A12 from elsewhere. (A12
on the stock socket sits where EPROMs/SRAM have CE/CS. Must have done
something wrong. 800XL jumped into memory test and the last 1/6th of
memory failed. I reworked the NAND gate ICs and simplified the project
even further by trying to just create the $D700 page of memory (It's
part of Bob Woolley's complete project). Unlike the -BASIC select line
which gets controlled by the OS (cart/no cart) the -$D700 is always
available. I thought it would make troubleshooting easier.

I finally got RAM to appear at $D700 but I must have the gates wrong.
When I write 256 bytes of information to that page about 5 bytes are
wrong. On successive reads the data starts to change.

Frankly, this is probably no project for a Noob like me but I'll keep
working at it.

At least I'm learning, though it seems the more I learn the more I
realize I don't understand what I'm really doing. LOL!

My 800XL is now a nest of wires

At least I haven't destroyed the 800XL. Yet!

- Steve Sheppard

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