The figtronix link broke because I asked him a question about his main rom
adapter a couple weeks ago, and he updated the board, just the silkscreen
not anything functional, and he removed the old link and made a new one. I
don't know if that's just the way oshpark works or if he's just doing
something wrong.
He ended up doing a bunch of stuff that I wanted for free and without
asking, so I wasn't going to complain about a little thing like it's
annoying having to keep finding out the new link!
We ended up trading a lot of emails and he whipped up both the option rom
board and the programmer adapter after I showed him the club100 links to the
old EME option rom module. There were several rapid iterations of both of
those and he did the same thing each time with those too, broke the existing
link and made a new one. And it takes forever before they show up in the
oshpark search too.
(Oh yeah, don't trust that search. Find any working link to any board by
that guy, then click on the guy's name, and THERE you see all his other
boards, including all 3 M100-related, even though they don't show up in the
search.)
Anyway there's lot's of ways to skin the same cat of course.
I like your board too. I actually assembled one of your boards too, but I'm
using the figtronix at the moment, because I don't want a combined system
and option rom, I want to be able to use the external accessible option rom
socket to swap roms and install commercial roms, and I want the system rom
to be socketed and re-programmable or at least swappable. I actually found
ceramic uv-erasable clcc 27C256, but even replacing OTP plcc ones is better
than needing a test-clip.
One thing I should verify, maybe there IS actually room to solder your board
on the motherboard and put a dip socket on the adapter, then trim the legs
of the eprom a little so the eprom sits lower in the socket, does the
resulting stack come out 0.55" or shorter? That would meet all my same
wishes above. Takes a standard eprom, and the eprom is removable and
reprogrammable with no special adapters.
Ideally I'd like both the main and option roms to use the same kind of
eprom. not plcc in one and soic in the other. There is just barely vertical
room for a low profile plcc socket in the option rom, but low profile plcc
sockets are surface mount so soldering them at home is not simple like the
regular socket with thru pins. I have old commercial option roms that used a
full dip28 eprom on a board. it's a tight fit but it works. The holes for
the eprom are actually pulled in a little closer than the proper dip28
spacing, squished inside the half-holes on the edges which are at dip28
spacing. No room for a socket, so a board like that you could only
re-program with either a test clip or a programming adapter, but that's no
worse than what you already need for the soic board. But at least then that,
along with your main rom board, means you'd have the same kind of part on
both system and option roms.
I mean IDEALLY of course, I'd love a REX, but I emailed the address on
club100 a couple times and never got any answer, and the plans for REX
aren't published like on oshpark, so oh well. Even if by a miracle one REX
became available from somewhere, I still probably wouldn't want to invest
time hacking with it if no one else could ever make use of the results. If
the REX were reproducible at will and anyone could have one, THEN it would
be a worthwhile target for hacking/developing. If not, then I'd rather just
start a new public/open design even if it's cruder and reinventing the
wheel.
(And now that I say that, I realize I sure like my MISE, and that's
basically in the same boat. The design is not public. The guy just happens
to be actively producing and supporting it right now. So maybe I'm being
inconsistent. At least I made my enclosure for the MISE public, including a
slick non-trivial arrangement to hold the cf card reader which does not have
any nice mounting holes or anything, if I do say so myself. ;) )
In the 102 of course I just stuck a plain socket in and a plain dip 27c256.
No complications there. Same goes for late m100 too apparently though both
my m100's needed the adapter.
--
bkw
On Mon, May 16, 2016 at 3:54 PM, Mike Stein <mhs.st...@gmail.com> wrote:
Thanks for posting those links. When I mentioned the various options for
adding/upgrading System and Option ROMs I wanted to include this one but at
the time the link at Oshpark didn't seem to work; I couldn't find any
mention on his Figtronix site either so I assumed they were no longer
available for some reason. Glad to see they're back and he's added a
programming adapter.
One advantage of those boards over the board Bill and Steve are discussing
is that in a T102 you can add an Option ROM without removing the System ROM
chip; however, at the risk of being immodest I should point out what I think
are some advantages of the 'Combo' board:
Whether you want to upgrade the System ROM and/or add an Option ROM in
either an old or a new M100/T102 you use the same board; no need for
separate System and Option ROM adapters.
To (re)program the IC in an 'old' M100 you'll need another adapter to
convert the pinout back to standard JEDEC; no problem, just assemble another
adapter 'in reverse' as it were, with a socket.
So the one PCB essentially does the same job as all three different
Figtronix ones; since you get a minimum of six boards you might save some
money.
Finally, since it uses a standard 28-pin socket if you want to play around
with the System ROM code without burning/replacing/reprogramming the
E(E)PROM every time, replace it with a non-volatile RAM chip like the Dallas
DS1230Y or the FM1808 FRAM and a minor mod to connect R/W and you can POKE
around all you want..
m
----- Original Message -----
From: Brian White
To: Model 100 Discussion
Sent: Saturday, May 14, 2016 11:42 PM
Subject: Re: [M100] ROM burning questions
...Re-post without pic...
Old m100 takes a non-standard pinout, new m100 and all t102 takes a
standard 27C256 pinout.
I just did an old m100 using this plcc adapter:
https://oshpark.com/shared_projects/toQDqmVV
I burned the Tandy 102 rom with y2k patches from the rex page on
bitchin100.
The board is easy to assemble except the only hitch is you have to find
pin headers that have thinner round pins rather than the more common square.
If you have a "new" m100, the chip number on the rom will not match the
number silkscreened on this board. In that case you don't need any adapter,
just put in a 27C256 dip28 directly, same as for T102.
https://goo.gl/photos/GUKXgxxVGaUVt57k9
--
bkw
