3.5" 1.44 floppy on a Tandy 1000 HX?
M B Wehr (Bruce)
an old "IBM compatible" computer they no longer used as thanks. He
called me tonight, saying he couldn't read some disks. A few
questions pinpointed the problem: he was trying to read HD floppies
on a LD drive.
"Hey, I have an old 3.5" HD drive I replaced in my computer a bit
ago," I said. "You can have it - I'll even install it for you!"
Well, his "IBM compatible" turned out to be a Tandy 1000 HX. 256K
RAM, 720 3.5" drive (no hard drive), and what appears to be CGA mono.
Not bad for an afternoon's labor! "It's IBM compatible, let's go!" I
thought.
The first thing that wrinkled my brow was that there was no power
cable going to the existing drive. Huh? Power thru the 34 pin ribbon
cable? I didn't know you could do that! (I'm more of a software
type, not heavy into the hardware.) Well, let's just do it! But,
after connecting my drive, the machine won't even power up. I'm
guessing that my drive must short out the computer's supply,
activating some sort of short-circuit protection. We called the local
Radio Shack - HD flops for the 1000 HX would have to be ordered at
$110 ea - not an option for this kid.
The next thing that I found a tad strange is that, despite having no
hard drive, the machine boots from C: and switches to A:. C:
appears to be a RAM-disk, which apparently is initialized during boot
from ROM and appears to have DOS 2.11. I wonder if that would prevent
his upgrading to a higher version of DOS. (I had brought DOS 5.0 with
me, but on HD disks - I was sure I'd get the drive working.)
I will probably be this kid's first line of support for this machine -
it would be best for me to learn as much as possible as quickly as
possible. So, be forewarned: I will probably use this group as *my*
first line of support (if folks 'round here don't mind, that is :-).
You folks have already been an immense help:
My news server keeps about 10-14 days of news. Earlier articles in
this group have mentioned that Tandy 3.5 flops use non-standard
wiring. They further said that typical drives could be modified, but
details weren't readily recalled. Other notes talked about the
FAX-back service at (800)THE-SHACK. I'll check that source next.
In case FAX-back doesn't answer them, these are my most pressing
questions: Does anyone know off the top of their heads what mods a
typical 3.5" flop needs to run on a 1000 HX? How about upgrading DOS:
is it possible, or is the version apparently in ROM what you get? How
compatible are these things, from both the hardware & software point
of view? Will only Tandy hardware options/upgrades (memory/video/serial
cards, etc.) work?
Sorry for all the questions - Tandy's are completely new to me. I'm
hoping that I can support my friend's son adequately, and that this
group won't mind a question or two. (Future notes won't be so
question-packed, I promise! :-) Thanks for all the help you've been
already.
+========================================+==================================+
Bruce Wehr - bw...@ford.com | "The country is never safer than
| when Congress is out of session"
Ford Motor Company - Dearborn, Michigan | -- The Home School Court Report
+========================================+==================================+
Leonard Erickson
> The first thing that wrinkled my brow was that there was no power
> cable going to the existing drive. Huh? Power thru the 34 pin ribbon
> cable? I didn't know you could do that!
As you found out, it takes special drives. Putting "normal" drives in
there can fry the power supply.
> We called the local
> Radio Shack - HD flops for the 1000 HX would have to be ordered at
> $110 ea - not an option for this kid.
It won't help anyway. The HX won't handle a 1.44 drive anyway. Check
the fine print in the catalog. There's a list of the catalog numbers of
the computers that it fits.
> The next thing that I found a tad strange is that, despite having no
> hard drive, the machine boots from C: and switches to A:. C:
> appears to be a RAM-disk, which apparently is initialized during boot
> from ROM and appears to have DOS 2.11.
Nope. It's a ROM-disk! No RAM involved at all. Several Tandy systems
had them. It's very handy if you think you've got a virus. Re-enable
booting from the ROM and run the anti-virus software from a write
protected floppy. There's nothing the virus can do to the floppy or the
OS! :-)
> I wonder if that would prevent
> his upgrading to a higher version of DOS. (I had brought DOS 5.0 with
> me, but on HD disks - I was sure I'd get the drive working.)
Nope. There's a setup program (or maybe a DIP switch on the HX) that
lets you set whether to boot from ROM, HD, or floppy.
Upgrading DOS versions is no problem. But, given that the machine is XT
compatible, not AT compatible, all any DOS version more recent than
3.31 does is waste RAM. You might ask around and try to find a copy of
DOS 3.30 or 3.31 for him. It'll make much better use of the RAM than
the later versions.
> I will probably be this kid's first line of support for this machine -
> it would be best for me to learn as much as possible as quickly as
> possible.
Well, as you've no doubt noticed, there aren't any card slots in the
system. Instead it uses "pin" connectors for boards. This is called the
PLUS interface by Tandy. It's exactly the same pinout as an 8-bit card
so it is possible to use regular boards, if you get an adapter.
Somebody just posted the address to ftp the FAQ from, so I won't repeat
it. Check it out, a couple of the listed companies make a box with
normal card slots. You run a cable from it to the PLUS connector, then
just stick the cards into the box.
It's not a bad system, but his best bet for expansion is haunting the
flea markets, and having you watch for folks dumping old gear here.
> How compatible are these things, from both the hardware & software point
> of view?
Hardware is pretty compatible, but be warned that the Tandy 1000 line
started as clones of the PCjr! They got more "normal" as time went on.
Main things to watch out for is that IRQ2 is the HD, and IRQ5 is used
for video. On an XT IRQ5 is the HD, and IRQ 2 is "free". Later models
have dip switches to swap these. But a *lot* of HD controllers are
available that'll work with just a jumper change.
Software should work. Do note that the 1000 has some extra video modes
and some special sound support. Most of the older Sierra games were
specifically written *for* these systems!
> Will only Tandy hardware options/upgrades (memory/video/serial
> cards, etc.) work?
On the HX, only Tandy or a few third party "cards" will work because of
the PLUS interface. But if you can get that box I mentioned, you can
use normal cards.
Oh yeah, if it didn't come with a printer cable, you'll have to buy a
special one. Be sure to get the one for hooking to *non*-Tandy printers.
Leonard Erickson leo...@qiclab.scn.rain.com
(aka Shadow) sha...@krypton.rain.com (preferred)
FIDO: 1:105/51 Leonard....@f51.n105.z1.fidonet.org
M B Wehr (Bruce)
> As you found out, it takes special drives. Putting "normal" drives in
> there can fry the power supply.
Yup, I certainly found that out! I was hoping to be able to modify my
old drive, but alas ...
> It won't help anyway. The HX won't handle a 1.44 drive anyway.
That's disappointing to hear. We even tried covering the second hole
on some HD disks (with some handy-man's special, duct tape! Hey, at
least it's opaque :-) Formatting them on the HX still didn't work.
Any ideas?
> Somebody just posted the address to ftp the FAQ from, so I won't repeat
> it. Check it out, a couple of the listed companies make a box with
> normal card slots.
Hmmm ... that's odd. When I first hooked up with this group a few
days ago, one of the first notes I read said that there was no
comp.sys.tandy FAQ. If that's changed, I didn't see the note. If
it's ftp.kjsl.com that you're referring to, then yes: I plan to check
that site soon to see what gems it holds. But, if there truly is a
Tandy FAQ, I'd appreciate someone letting me know where to get a copy.
Thanks for all the help, Leonard!
Dan Franco
1. Tandy had a "memory plus expansion card" that contained 128k of
RAM, and provided more slots to add chips to take you up to 640k. If
you can get one third-party, that might be your best bet to upgrade
memory.
2. The video was 16-color CGA - not bad in its day, when compared to
IBM's 4-color CGA.
If I remember anything else I'll let you know.
Leonard Erickson
> That's disappointing to hear. We even tried covering the second hole
> on some HD disks (with some handy-man's special, duct tape! Hey, at
> least it's opaque :-) Formatting them on the HX still didn't work.
> Any ideas?
You have to use DSDD disks in a 720k drive. The oxide coating is *not*
the same as on DSHD disks! You should still be able to locate 720k
disks, in fact they are ridiculously cheap if ordered inbulk via mail
order.