Reading TRS-80 discs (was RE: Archiving old discs...)

From: CLASSICCMP_at_trailing-edge.com <(CLASSICCMP_at_trailing-edge.com)>
Date: Tue Sep 14 13:26:41 1999

--- morrison_at_t-iii.com wrote:
> If the TRS-80 disks are DD you can usually read them OK, but SD needs some
> other computer (Model I, III, 4, Coco etc.)

There has been extensive discussion on this topic on the comp.os.cpm
newsgroup in the past several years. Here's some articles that detail
which PC floppy disk controllers are capable of reading/writing single-
density disks:
   
Ken Ganshirt <ken.ganshirt_at_sk.sympatico.ca> wrote in article
<36899CB0.19AD9093_at_sk.sympatico.ca>...
>
> I must have a pretty decent floppy controller, because I can even read
> my original SS/SD Os-1 floppies, even though 22Disk warns that it might
> not work for that format. (For the technically curious, this is on a
> Dell 486/50 running Win 95 and the floppy drive is one of those deals
> that has both a 3.5 and 5.25 in a single half-height drive. It's the
> only system I have left with a 5.25" floppy drive.)
>

Ken,

I recently did a study to find out what will and what won't do single
density. Here are my findings so far:

Will support single density / FM:

        NS PC87306 Super I/O
        SMC FDC37C65
        SMC FDC37C78
        Most SMC Super I/O chips

Will NOT support single density / FM:

        NS 8473
        NS PC87332* Super I/O
        NS PC97307* Super I/O
        WD FDC37C65
        Most (if not all) Intel parts
        Any Winbond part
        Any UMC part

Reportedly will do single density / FM but NOT verified:

        NS 8477
        Intel 82077AA
        Goldstar Super I/O

The NS PC87306 is found in a lot of Dell and Compaq machines from the
486-50Mhz models to the Pentium-90 models. Most Super Micro Pentium
motherboards using the PCI HX chipset also used that super I/O.

*NOTE: It is important to verify the part number on the chip itself. Many
of these newer NS parts will identify themselves to software as PC87306,
but do NOT support single density.

Best regards,
Amardeep
   
Amardeep S. Chana (asc1000_at_ibm.net) wrote:
: Ken Ganshirt <ken.ganshirt_at_sk.sympatico.ca> wrote in article
: <36899CB0.19AD9093_at_sk.sympatico.ca>...
: >
: > I must have a pretty decent floppy controller, because I can even read
: > my original SS/SD Os-1 floppies, even though 22Disk warns that it might
: > not work for that format. (For the technically curious, this is on a
: > Dell 486/50 running Win 95 and the floppy drive is one of those deals
: > that has both a 3.5 and 5.25 in a single half-height drive. It's the
: > only system I have left with a 5.25" floppy drive.)
: >

: Ken,

: I recently did a study to find out what will and what won't do single
: density. Here are my findings so far:

Amardeep, I fear that I must question your study. I believe that you
are ascribing to some of the chips the shortcomings of the FDC
manufacturer. For example, both the NS 8473 and the WD 37C65 will
most assuredly support FM. I have DTK FDC cards with the 8473 and
read Osborne 1 disks with them just prior to writing this. Likewise,
I have the WD 37C65 in the WD FOX card and it will also read/write
FM. On that basis, I must have reservations about some of your other
determinations.
                                                 - don

: Will support single density / FM:

: NS PC87306 Super I/O
: SMC FDC37C65
: SMC FDC37C78
: Most SMC Super I/O chips

: Will NOT support single density / FM:

: NS 8473
: NS PC87332* Super I/O
: NS PC97307* Super I/O
: WD FDC37C65
: Most (if not all) Intel parts
: Any Winbond part
: Any UMC part

: Reportedly will do single density / FM but NOT verified:

: NS 8477
: Intel 82077AA
: Goldstar Super I/O

: The NS PC87306 is found in a lot of Dell and Compaq machines from the
: 486-50Mhz models to the Pentium-90 models. Most Super Micro Pentium
: motherboards using the PCI HX chipset also used that super I/O.

: *NOTE: It is important to verify the part number on the chip itself. Many
: of these newer NS parts will identify themselves to software as PC87306,
: but do NOT support single density.

: Best regards,
: Amardeep

Don Maslin <donm_at_cts.com> wrote in article
<915064276.933215_at_optional.cts.com>...
[snip]
>
> Amardeep, I fear that I must question your study. I believe that you
> are ascribing to some of the chips the shortcomings of the FDC
> manufacturer. For example, both the NS 8473 and the WD 37C65 will
> most assuredly support FM. I have DTK FDC cards with the 8473 and
> read Osborne 1 disks with them just prior to writing this. Likewise,
> I have the WD 37C65 in the WD FOX card and it will also read/write
> FM. On that basis, I must have reservations about some of your other
> determinations.
> - don
>

Hi Don,

I understand your reservations and can address every issue. I did not go
into enough detail in the first posting to fully support my assertions.

> : Will support single density / FM:
>
> : NS PC87306 Super I/O
> : SMC FDC37C65
> : SMC FDC37C78
> : Most SMC Super I/O chips
>

The above parts are completely stand alone with on board filters, write
precomp generators, and data separators. They should work with FM in any
board implementation, unless something specific is done to prevent it (not
likely). This is per the National and SMSC (new name for SMC
semiconductor) data sheets. I have tested the NS PC87306 and SMC FDC37C65
using Jeff Vavasour's Model 4 emulator and Tim Mann's xtrs 2.8 under Linux.
 They both read and write FM with no problems.

> : Will NOT support single density / FM:
>
> : NS 8473
> : NS PC87332* Super I/O
> : NS PC97307* Super I/O
> : WD FDC37C65
> : Most (if not all) Intel parts
> : Any Winbond part
> : Any UMC part
>

The 1988 data sheet for the NS 8473 states on page 8-32, "While the
controller and data separator support both FM and MFM encoding, the filter
switch circuitry only supports the IBM standard MFM data rates. To provide
both FM and MFM filters external logic may be necessary."

Every 8473 board I have tried failed to write FM. However, it may be
possible to read FM on some boards if the external filters have a wide
enough Q.

The NS PC87332 & NS PC97307 are standalone and by design do not support FM
(verified on the National data sheets).

The only information I have on the WD FDC37C65 is the Always IN2000 card I
have with that chip cannot read or write FM. I suspect it is also
dependent on implementation.

I have new information on Intel...

        Intel 8272 is a NEC 765 clone and therefore dependent on implementation
.
        Intel 82077AA and 82077SL - data sheet clearly states these parts suppo
rt
FM.

Thanks to Pete Cervasio for testing and reporting that the 82077 does
indeed read and write FM.

        Intel 82078 - data sheet clearly states these parts will NOT support FM
.

I haven't yet investigated the new Intel Super I/O chip which is replacing
the 82078.

The Winbond and UMC chips have never worked on any adapter or motherboard
I've ever encountered them on. No idea if its the chip or the
implementation.

> : Reportedly will do single density / FM but NOT verified:
>
> : NS 8477
> : Intel 82077AA
> : Goldstar Super I/O
>

The NS 8477 data sheet indicates that it does support FM (it is
functionally and pin for pin compatible with the Intel 82077). The
Goldstar Super I/O was reported to work with FM in a newsgroup posting I
read once but have never been able to confirm it.

Hope that clarifies things :)

Amardeep
Received on Tue Sep 14 1999 - 13:26:41 BST