Hardware Guru for Hire?
Tom Lake
so I'm looking for a person who can build me an interface cable to allow a
5.25"
floppy drive to be attached to a USB port. I see lots of 3.5" drives with
USB
interface but no 5.25". I figure it can't be too hard to convert one to the
other for
someone who knows what (s)he's doing (certainly not me!) Any takers?
Tom Lake
Barry Watzman
But as a hardware person (somewhat, but this is probably beyond me),
what you want is a LOT more than a cable.
Unfortunately, the 3.5" USB drives are all made as integrated devices
... they are not simply USB to floppy converters with a "standard" (e.g.
34 pin) 3.5" drive.
I want a USB to "standard floppy" controller, ideally it should support
5.25" drives (both 360k and 1.2M) and even 8" drives. I think there is
a market for it (not huge, but large enough to pay for development and
production). But no such device currently exists.
craigm
> I want one too.....
>
> But as a hardware person (somewhat, but this is probably beyond me),
> what you want is a LOT more than a cable.
>
> Unfortunately, the 3.5" USB drives are all made as integrated devices
> ... they are not simply USB to floppy converters with a "standard" (e.g.
> 34 pin) 3.5" drive.
>
> I want a USB to "standard floppy" controller, ideally it should support
> 5.25" drives (both 360k and 1.2M) and even 8" drives. I think there is
> a market for it (not huge, but large enough to pay for development and
> production). But no such device currently exists.
>
>
How close is this?
http://www.smsc.com/main/catalog/usb97cfdc2_01.html
Tom Lake
>> 5.25" drives (both 360k and 1.2M) and even 8" drives. I think there is
>> a market for it (not huge, but large enough to pay for development and
>> production). But no such device currently exists.
>>
>>
>
> How close is this?
> http://www.smsc.com/main/catalog/usb97cfdc2_01.html
I don't see support for 360K or 180K but it does look
like it's close!
Tom Lake
glen herrmannsfeldt
For 8" drives you usually need TG43, indicating the track being
written is greater than track 43, and the write current should be
reduced. It would seem that the included firmware doesn't do
that, but it might not be hard to do. For 360K drives, don't
go past track 40. I don't see support for single sided, though.
-- glen
Holger Petersen
>go past track 40. I don't see support for single sided, though.
You mean "single Density", dont you?
Yours, Holger
s_dub...@yahoo.com
>
> - Show quoted text -
I'm curious about what you both would expect to pay for such a
device. The little I know about USB is that it is closer to packet
based communication than normal serial communication.
Steve
Tom Lake
> device. The little I know about USB is that it is closer to packet
> based communication than normal serial communication.
I have literally hundreds of 5.25" floppies and none of my current PCs
can read them. I suppose I'd pay a few hundred to be able to read them.
Since I know nothing about hardware, I figured that if it's possible to
create
a 3.5" version for around $20, then a 5.25" version shouldn't be too hard.
Tom Lake
Barry Watzman
could form the basis of a finished product. However, while I'm not
familiar with that particular one (and there are others), these were
intended, for the most part, for use in PCs with 3.5" drives. So there
are a number of issues to investigate:
-Is FM encoding supported (necessary for SSSD 8")
-Are various data rates supported (necessary for all formats other then
3.5" 1.44MB)
-Are all 4 commonly used sector sizes supported (128, 256, 512, 1,024
bytes)? PCs ONLY use 512 bytes
-Is the chip in some way operating system specific (to PC formats)?
-How flexible is the chip? For example, will it support media that has
totally different formats on different tracks (many early 8" double
density disks had some tracks recorded in single density)
-Will it support formats that the Western Digital chips (17xx series)
could create but that the 765 series controllers are incapable of
dealing with?
I don't know the answers to these (and other) questions, but not all of
the chip products will work for a general purpose non-PC disk drive of
possibly 5.25" 360k, 5.25" 1.2MB and 8" (various formats, many
"oddball"). It's all part of getting from a chip to a finished product.
Barry Watzman
50 pin connectors for 5.25" and 8" drives) should cost about $100, I'd
think. Supply your own drives, power supply, case and cables. Software
would have to be included to allow PC use (MS-DOS formatting and use),
low level access and possibly common (e.g. CP/M) file transfer in both
directions.
no....@no.uce.bellatlantic.net
wrote:
Simple solution you can do.
1) find and older PC that has a floppy. (stay pre P500).
2) install a 5.25" floppy
3) read said floppies to the limits of the 5.25 drives and PC floppy
controller.
USB device buys you nothing over that and may even be worse.
Allison
no....@no.uce.bellatlantic.net
<Watzma...@neo.rr.com> wrote:
>That's a CHIP, not a finished product. There are a number of chips that
Yep ther anre many bot most are similar.
>could form the basis of a finished product. However, while I'm not
>familiar with that particular one (and there are others), these were
>intended, for the most part, for use in PCs with 3.5" drives. So there
>are a number of issues to investigate:
>
>-Is FM encoding supported (necessary for SSSD 8")
Maybe depending on data rate.
>-Are various data rates supported (necessary for all formats other then
>3.5" 1.44MB)
Programming issue.
>-Are all 4 commonly used sector sizes supported (128, 256, 512, 1,024
>bytes)? PCs ONLY use 512 bytes
Programming issue but may also be limited by ram buffer.
>-Is the chip in some way operating system specific (to PC formats)?
Thats the USB driver issue, technically a programming issue but
constipated by the fact taht USB and the Miclyspooge OS are a PITA.
Likely worse if the OS is win2k or XP.
>-How flexible is the chip? For example, will it support media that has
>totally different formats on different tracks (many early 8" double
>density disks had some tracks recorded in single density)
Again that is a programming issue.
>-Will it support formats that the Western Digital chips (17xx series)
>could create but that the 765 series controllers are incapable of
>dealing with?
There lies the dirty dawg. Most use a 765 core for the floppy
controler and therefor it has no special properties over the average
PC chipset that uses the 765 core.
FYI: some of the 1771 formats can't be read even with the 1793!
Generally those chips are a cpu, ram, memory (eeprom/ram) and of
course the FDC and USB IO and hopefully DMA (for speed). What they
do and how they do it is programable but... After programming the
chip you also have to have a driver that knows what the device can do
to exploit it. Programming a PC at the driver level for XP is likely
the least fun thing I can think of.
>I don't know the answers to these (and other) questions, but not all of
>the chip products will work for a general purpose non-PC disk drive of
>possibly 5.25" 360k, 5.25" 1.2MB and 8" (various formats, many
>"oddball"). It's all part of getting from a chip to a finished product.
>
It's 765 based so if it doesn't work on most PCs over the last 10
years the USB thingie isn't likely to do it either.
The easiest and cheapest solution is to pick up and older PC
and use that as the FDC in those supports two floppy drives
and still has a drive bay that can accept a 5.25" drive. FYI:
the older the better (486 works too). Generally those machine
are found on the curb working and for free. It will not solve 100%
of the problem but the cases that don't fly are things like some 8",
some 5.25" oddballs and of course any hard sectored stuff.
For an OS load up w98se as it does networking and is still close to
DOS and will fit easily on a 500Mb or larger disk.
Allison
Barry Watzman
require hardware support in the FDC chip and associated circuitry and if
it's not present, there is no software workaround.
glen herrmannsfeldt
> That's a CHIP, not a finished product. There are a number of chips that
> could form the basis of a finished product. However, while I'm not
> familiar with that particular one (and there are others), these were
> intended, for the most part, for use in PCs with 3.5" drives. So there
> are a number of issues to investigate:
I believe the floppy disk controller in the previously mentioned
chip is the same as the one in:
http://www.smsc.com/main/datasheets/37c669.pdf
The data sheet mentions 37c869, but the only reference to that at SMSC
is that data sheet itself.
> -Is FM encoding supported (necessary for SSSD 8")
The 37C669 supports FM and MFM
> -Are various data rates supported (necessary for all formats other then
> 3.5" 1.44MB)
Data rates from 125Kb/s (FM/5.25) up to 1Mb/s or 2Mb/s.
(125Kb/s only in FM mode, higher than 250Kb/s only in MFM mode.)
See table 11 on page 28.
> -Are all 4 commonly used sector sizes supported (128, 256, 512, 1,024
> bytes)? PCs ONLY use 512 bytes
128, 256, 512, 1024, 2048, 4096, 8192, 16384.
> -Is the chip in some way operating system specific (to PC formats)?
It claims 765B and 82077AA compatibility.
> -How flexible is the chip? For example, will it support media that has
> totally different formats on different tracks (many early 8" double
> density disks had some tracks recorded in single density)
> -Will it support formats that the Western Digital chips (17xx series)
> could create but that the 765 series controllers are incapable of
> dealing with?
What would those formats be?
Note that this all describes what the hardware can do. The USB/floppy
chip includes software (firmware) which may not be programmed to do
all those things. It may require disassembly, modification, and
reassembly to do it.
> I don't know the answers to these (and other) questions, but not all of
> the chip products will work for a general purpose non-PC disk drive of
> possibly 5.25" 360k, 5.25" 1.2MB and 8" (various formats, many
> "oddball"). It's all part of getting from a chip to a finished product.
Also, like most floppy disk controllers it doesn't generate the
reduced write current signal used by some 8 inch drives on inner
tracks. That would only be needed to write, not read, 8 inch disks.
-- glen
Richard Brady
[snip]
> The easiest and cheapest solution is to pick up and older PC
> and use that as the FDC in those supports two floppy drives
> and still has a drive bay that can accept a 5.25" drive. FYI:
> the older the better (486 works too). Generally those machine
> are found on the curb working and for free. It will not solve 100%
> of the problem but the cases that don't fly are things like some 8",
> some 5.25" oddballs and of course any hard sectored stuff.
> For an OS load up w98se as it does networking and is still close to
> DOS and will fit easily on a 500Mb or larger disk.
>
> Allison
>
Tom,
Allison sure has this right. I have a pentium XP with an internal 5.25
inch drive and an internal 3.5 inch drive. Reading DOS disks is ok, but
to read anything else, I've got to reboot in an old dos (PC DOS 7, in my
case); WinSE sounds better. The floppy disk drive uses the same cable
as the 3.5 inch drive. This does not work with hard sectored or other
oddball formats.
like you, I'm trying to get my 5.25 inch stuff on zip drives or at least
3.5 inch diskettes. I have a killer ram disk on my PC DOS 7 system, but
it has no hard disk under PC DOS 7. :-( Something about long file
names perhaps.
Good luck.
Richard Brady
Good luck.
glen herrmannsfeldt
> glen herrmannsfeldt <g...@ugcs.caltech.edu> writes:
I meant single side when I wrote that.
As I wrote today, the hardware can do many things, but the included
firmware may not know about them.
-- glen
no....@no.uce.bellatlantic.net
<Watzma...@neo.rr.com> wrote:
>Neither data rates nor sector sizes are programming issues. They both
>require hardware support in the FDC chip and associated circuitry and if
>it's not present, there is no software workaround.
Ok then. Last time I used a FDC I had to program it to do things.
Things like what sector size and how many just minor programming thats
all. That doesnt mean the FDC on board that beast can do it all but,
to get it to do anything requires programming. So variable sector
sizes, number of sectors, number of tracks, sides are programming
issues within the limits of the hardware. The chip being hardware
and dumb as a stump without programming and host support programming
on the other end of the USB.
Allison
glen herrmannsfeldt
> On Thu, 19 Jul 2007 10:11:55 -0400, Barry Watzman
> <Watzma...@neo.rr.com> wrote:
>>Neither data rates nor sector sizes are programming issues. They both
>>require hardware support in the FDC chip and associated circuitry and if
>>it's not present, there is no software workaround.
> Ok then. Last time I used a FDC I had to program it to do things.
> Things like what sector size and how many just minor programming thats
> all. That doesnt mean the FDC on board that beast can do it all but,
> to get it to do anything requires programming. So variable sector
> sizes, number of sectors, number of tracks, sides are programming
> issues within the limits of the hardware. The chip being hardware
> and dumb as a stump without programming and host support programming
> on the other end of the USB.
Yes, it needs programming on the other end to talk to USB, but the
chip does have 32K of ROM. It may or may not be that the ROM
has the ability to set those registers. If not, external ROM can
be used to do it.
-- glen
no....@no.uce.bellatlantic.net
<rrllb...@worrlldnet.att.net> wrote:
>no....@no.uce.bellatlantic.net wrote:
>[snip]
>
>> The easiest and cheapest solution is to pick up and older PC
>> and use that as the FDC in those supports two floppy drives
>> and still has a drive bay that can accept a 5.25" drive. FYI:
>> the older the better (486 works too). Generally those machine
>> are found on the curb working and for free. It will not solve 100%
>> of the problem but the cases that don't fly are things like some 8",
>> some 5.25" oddballs and of course any hard sectored stuff.
>> For an OS load up w98se as it does networking and is still close to
>> DOS and will fit easily on a 500Mb or larger disk.
>>
>> Allison
>>
>Tom,
>
>Allison sure has this right. I have a pentium XP with an internal 5.25
>inch drive and an internal 3.5 inch drive. Reading DOS disks is ok, but
>to read anything else, I've got to reboot in an old dos (PC DOS 7, in my
>case); WinSE sounds better. The floppy disk drive uses the same cable
>as the 3.5 inch drive. This does not work with hard sectored or other
>oddball formats.
My solution is a asus (OLD) 486DX/66 with 32mb of ram, 500mb disk,
5.25floppy (teac FD55GFR), 3.5" floppy and a 10mb NIC. Running W98se
thats been hacked with 98Lite for a smaller faster unfeature laden
machine. Works very nice and is actually useful for many other
things. Since the FDC is NOT on the MB I puicked one that uses a
37C65 which can do most all of the reasonable formats.
I also have a Celeron500 based box that can do same.
Both cost $0.00 as they were desined for the bin (skip).
Allison
no....@no.uce.bellatlantic.net
<g...@ugcs.caltech.edu> wrote:
>Barry Watzman wrote:
>
>> That's a CHIP, not a finished product. There are a number of chips that
>> could form the basis of a finished product. However, while I'm not
>> familiar with that particular one (and there are others), these were
>> intended, for the most part, for use in PCs with 3.5" drives. So there
>> are a number of issues to investigate:
>
>I believe the floppy disk controller in the previously mentioned
>chip is the same as the one in:
>
>http://www.smsc.com/main/datasheets/37c669.pdf
>
>The data sheet mentions 37c869, but the only reference to that at SMSC
>is that data sheet itself.
>
>> -Is FM encoding supported (necessary for SSSD 8")
>
>The 37C669 supports FM and MFM
Essenially 765 or the 37c65 as they are all the same core.
>
>> -Are various data rates supported (necessary for all formats other then
>> 3.5" 1.44MB)
>
>Data rates from 125Kb/s (FM/5.25) up to 1Mb/s or 2Mb/s.
>(125Kb/s only in FM mode, higher than 250Kb/s only in MFM mode.)
>See table 11 on page 28.
>
>> -Are all 4 commonly used sector sizes supported (128, 256, 512, 1,024
>> bytes)? PCs ONLY use 512 bytes
>
>128, 256, 512, 1024, 2048, 4096, 8192, 16384.
>
>> -Is the chip in some way operating system specific (to PC formats)?
>
>It claims 765B and 82077AA compatibility.
>
>> -How flexible is the chip? For example, will it support media that has
>> totally different formats on different tracks (many early 8" double
>> density disks had some tracks recorded in single density)
>> -Will it support formats that the Western Digital chips (17xx series)
>> could create but that the 765 series controllers are incapable of
>> dealing with?
>
>What would those formats be?
There were a few that used the 1771 user assigned data or sector
marks rather than standard and other cruft. The 1771 would do
anything you told it, not that that always made sense or conformed to
any stanard.
>
>Note that this all describes what the hardware can do. The USB/floppy
>chip includes software (firmware) which may not be programmed to do
>all those things. It may require disassembly, modification, and
>reassembly to do it.
Most likely as the user is asking to to not behave as a standard PC
FDC would.
>> I don't know the answers to these (and other) questions, but not all of
>> the chip products will work for a general purpose non-PC disk drive of
>> possibly 5.25" 360k, 5.25" 1.2MB and 8" (various formats, many
>> "oddball"). It's all part of getting from a chip to a finished product.
>
>Also, like most floppy disk controllers it doesn't generate the
>reduced write current signal used by some 8 inch drives on inner
>tracks. That would only be needed to write, not read, 8 inch disks.
This is not always required for all 8" drives and for reading it is
NOT a required thing.
Same for single sided, if you want only one side then don't even
access the other.
It's a embedded CPU with xyz peripherals aimed at the PC market and
while its fairly generalized there is no requirement to do all or be
all as a result. The PC always used a subset of the 765 floppy
controllers capability and while its programatically accessable the
hardware configuration was often a subset of the chips capability
as well.
Allison
Barry Watzman
A standard NEC 765 can do the 4 sector sizes that have been widely used
(128, 256, 512, 1024 bytes). But the USB-to-FDC chip in question
doesn't, taken as a whole, necessarily support everything that the 765
could do. PCs have only used the 512 byte sector size. The USB-to-FDC
chip is a whole microprocessor PLUS an FDC chip WITH A FIRMWARE
OPERATING SYSTEM. Even if the hardware component of this chip can do
all 4 sizes (likely, but not an absolute given), the firmware in the
stock chip might only do 512 bytes. There may be versions of this chip
that support external firmware, and on a volume basis, custom firmware
can be implemented and ordered. But if the discussion relates to the
most common mask firmware stock version(s) of the chip, it may not be
possible to implement sector sizes other than 512 bytes. I'm not saying
absolutely that it isn't, I'm saying it's an area for concern/investigation.
Also, in the context of my response that certain things might not be
"programmable", I was defining "programmable" as "programmable from the
PC via the USB connection", and I was referring to the "stock" version
of the chip, not a version with custom external firmware.
There is no doubt that what we want can be done (with this part or other
parts), but there is very great doubt that it can be done with the
stock, standard version of this chip and it's stock, standard internal
firmware.
glen herrmannsfeldt
> I was not as clear as I should have been in my previous post.
> A standard NEC 765 can do the 4 sector sizes that have been widely used
> (128, 256, 512, 1024 bytes). But the USB-to-FDC chip in question
> doesn't, taken as a whole, necessarily support everything that the 765
> could do. PCs have only used the 512 byte sector size. The USB-to-FDC
> chip is a whole microprocessor PLUS an FDC chip WITH A FIRMWARE
> OPERATING SYSTEM. Even if the hardware component of this chip can do
> all 4 sizes (likely, but not an absolute given),
The data sheet indicates that it is the standard SMSC floppy controller,
and I found a data sheet with a detailed description of that controller.
It seems to do 128, 256, 512, ..., 16384 sector sizes.
> the firmware in the
> stock chip might only do 512 bytes. There may be versions of this chip
> that support external firmware,
It does say how to use external firmware, by tying ROMEN low.
When internal firmware is used, a serial EEPROM supplies the USB
configuration data.
> and on a volume basis, custom firmware
> can be implemented and ordered. But if the discussion relates to the
> most common mask firmware stock version(s) of the chip, it may not be
> possible to implement sector sizes other than 512 bytes. I'm not saying
> absolutely that it isn't, I'm saying it's an area for
> concern/investigation.
The processors is an 8051, so the documentation should be easy
to find. I don't see that source code is available, but it might
be that it is. (with comments).
> Also, in the context of my response that certain things might not be
> "programmable", I was defining "programmable" as "programmable from the
> PC via the USB connection", and I was referring to the "stock" version
> of the chip, not a version with custom external firmware.
There is a pin to select external firmware, and pins to address
the external ROM. They don't seem to be optional.
> There is no doubt that what we want can be done (with this part or other
> parts), but there is very great doubt that it can be done with the
> stock, standard version of this chip and it's stock, standard internal
> firmware.
That is true.
-- glen
Bill
wrote:
>> I'm curious about what you both would expect to pay for such a
>> device. The little I know about USB is that it is closer to packet
>> based communication than normal serial communication.
>
>I have literally hundreds of 5.25" floppies and none of my current PCs
>can read them. I suppose I'd pay a few hundred to be able to read them.
You're joking, right?
This past weekend, I bought a little HP xe783 at auction for FIVE
BUCKS. It's got two 5-1/4'' drive bays, and if you only needed one
for your floppy drive, you could leave the CD Writer in the other - it
might come in useful. The 30gig drive should be able to hold every
CP/M disk image you could ever make..
If there's something missing, it's connectivity. While it has USB, it
gets connected through an optional PCI card - modem or ethernet,
your choice. At 700mhz it's not the worlds fastest, but hey, if all
you really want is to read floppies.....
I think I'd look for something like this. At least using ethernet it
could just be another network appliance. And, an actual spare
computer for those other times.
Total cost less than ten bucks.
Bill
I just finished installing Litepc98, and using Driver Genus was able
to find the right (and latest) drivers (thanks for nothing HP - they
removed them 30 June from their website) This little beastie really
trucks now - but I still might put Linux on it, anyway.
Tom Lake
news:46994ce2$0$4693$4c36...@roadrunner.com...
Hey,, guys, check out this link!
http://www.buslinkbuy.com/products.asp?sku=FDD1
Doesn't that look a lot like a complete floppy drive in a case with a
USB cable added? Other 3.5" USB solutions I've seen seem to
be a custom setup but this looks like it might be adaptable to my
purposes!
Tom Lake
craigm
Physically, you might be able to connect to a 5-1/4 inch drive. However, you
need to keep in mind the FW resident on the adapter and the drives in the
host PC's OS must also support what you want to do.
If what you want to do fits in the USB Mass Storage Class UFI specification
AND your PC fully implements that specification AND the adapter fully
implements the specification AND the hardware support everything you need,
then yes it might work.
However, if what you want to do falls outside any of these, then you'll need
to start with the hardware and work out all the details.
I would suspect that the software on the USB-floppy adapter is designed
around the specs for a 3.5" floppy and may not provide support for the
geometries and data rates used in a variety of 5.25" drives/disks.
This is why I referenced a chip earlier. I don't expect the solution to be
off-the-shelf, some work will be necessary.
Craig
Andrew J. Kroll
considering it states "1 Mbps, 500 Kbps, 300 Kbps, 250 Kbps Data Rates" You
are looking at the usual rates for FM and MFM, and those are all there. :-)
if it is a 765, it will do them, see also in the info about custom
firmwares :-)
glen herrmannsfeldt
(snip)
> considering it states "1 Mbps, 500 Kbps, 300 Kbps, 250 Kbps Data Rates" You
> are looking at the usual rates for FM and MFM, and those are all there. :-)
> if it is a 765, it will do them, see also in the info about custom
> firmwares :-)
After my previous posts, I realize that it might not be possible
to read the internal ROM from outside. One would then have to ask
for the code, which hopefully would be available in source form.
-- glen
Barry Watzman
volume, that the code is available. Now for a quantity one (or ten, for
that matter), it's another matter.
Holger Petersen
>considering it states "1 Mbps, 500 Kbps, 300 Kbps, 250 Kbps Data Rates" You
>are looking at the usual rates for FM and MFM, and those are all there. :-)
No. FM on 5.25 inch is 125 Kbps...
>if it is a 765, it will do them, see also in the info about custom
>firmwares :-)
IF it is a original clone of the 765, it wont do 128 Bytes/Sektor in DD...
SCNR, Holger
glen herrmannsfeldt
> "Andrew J. Kroll" <a...@oo.ms> writes:
>>considering it states "1 Mbps, 500 Kbps, 300 Kbps, 250 Kbps Data Rates" You
>>are looking at the usual rates for FM and MFM, and those are all there. :-)
And it does those rates with a 14.318 MHz crystal...
> No. FM on 5.25 inch is 125 Kbps...
>>if it is a 765, it will do them, see also in the info about custom
>>firmwares :-)
> IF it is a original clone of the 765, it wont do 128 Bytes/Sektor in DD...
I don't see any connection between data rate and sector size.
It won't do 125Kb/s in MFM mode, but it looks like it will do any
sector size of 2**N with N from 7 to 14.
Look at the 37C669 data sheet.
-- glen
no....@no.uce.bellatlantic.net
<g...@ugcs.caltech.edu> wrote:
>Holger Petersen wrote:
>> "Andrew J. Kroll" <a...@oo.ms> writes:
>
>>>considering it states "1 Mbps, 500 Kbps, 300 Kbps, 250 Kbps Data Rates" You
>>>are looking at the usual rates for FM and MFM, and those are all there. :-)
>
>And it does those rates with a 14.318 MHz crystal...
Your kidding? There's no easy way to divide 14.31818Mhz to 500,000Hz
or any of the lower data rates. Though current tech chips could
include a PLL to synthisize the required clocks given a reference.
>> No. FM on 5.25 inch is 125 Kbps...
>
>>>if it is a 765, it will do them, see also in the info about custom
>>>firmwares :-)
>
>> IF it is a original clone of the 765, it wont do 128 Bytes/Sektor in DD...
>
>I don't see any connection between data rate and sector size.
>
>It won't do 125Kb/s in MFM mode, but it looks like it will do any
>sector size of 2**N with N from 7 to 14.
There is no connection between data rate and sector size. There is
a connection between SD(FM) and DD(MFM) and sector size.
It is a 765 core.
Allison
glen herrmannsfeldt
> On Tue, 24 Jul 2007 04:56:52 -0800, glen herrmannsfeldt
> <g...@ugcs.caltech.edu> wrote:
>>>"Andrew J. Kroll" <a...@oo.ms> writes:
>>>>considering it states "1 Mbps, 500 Kbps, 300 Kbps, 250 Kbps Data Rates" You
>>>>are looking at the usual rates for FM and MFM, and those are all there. :-)
>>And it does those rates with a 14.318 MHz crystal...
> Your kidding? There's no easy way to divide 14.31818Mhz to 500,000Hz
> or any of the lower data rates. Though current tech chips could
> include a PLL to synthisize the required clocks given a reference.
Precompensation requires a higher clock rate. It seems to do it in
multiples of 41.677ns, for a 24MHz clock. So a PLL seems likely.
>>>No. FM on 5.25 inch is 125 Kbps...
>>>>if it is a 765, it will do them, see also in the info about custom
>>>>firmwares :-)
>>>IF it is a original clone of the 765, it wont do 128 Bytes/Sektor in DD...
>>I don't see any connection between data rate and sector size.
>>It won't do 125Kb/s in MFM mode, but it looks like it will do any
>>sector size of 2**N with N from 7 to 14.
> There is no connection between data rate and sector size. There is
> a connection between SD(FM) and DD(MFM) and sector size.
> It is a 765 core.
It is also an 82077A core. I don't have the 765 data sheet nearby.
I do have the 82077A, but it isn't nearby right now.
Will the 765 do 16384 byte sectors?
It will also do 1Mb/s and 2Mb/s. 1Mb/s is for ED floppies,
I believe 2Mb/s is used for some floppy tape formats.
-- glen
no....@no.uce.bellatlantic.net
<g...@ugcs.caltech.edu> wrote:
82077 is decended from 765.
>
>Will the 765 do 16384 byte sectors?
Yes. What floppy can do that?
>It will also do 1Mb/s and 2Mb/s. 1Mb/s is for ED floppies,
>I believe 2Mb/s is used for some floppy tape formats.
ED floppies came and went so f ast I never got to play with one.
However I have a few of those Travan backup hacks though they
didn't seem to stress the FDC any.
Allison
>
>-- glen
no....@no.uce.bellatlantic.net
<g...@ugcs.caltech.edu> wrote:
Yes. The 82077A is decended from the 765 core.
What drive can do 16kB sectors?
>
>It will also do 1Mb/s and 2Mb/s. 1Mb/s is for ED floppies,
>I believe 2Mb/s is used for some floppy tape formats.
Possibly, though that sounds like the travan tape for
floppy as backup thing.
Allison
glen herrmannsfeldt
> On Tue, 24 Jul 2007 11:20:00 -0800, glen herrmannsfeldt
> <g...@ugcs.caltech.edu> wrote:
(snip)
>>It is also an 82077A core. I don't have the 765 data sheet nearby.
>>I do have the 82077A, but it isn't nearby right now.
> 82077 is decended from 765.
>>Will the 765 do 16384 byte sectors?
> Yes. What floppy can do that?
I think ED can do it, one sector per track.
Otherwise, for floppy tapes.
>>It will also do 1Mb/s and 2Mb/s. 1Mb/s is for ED floppies,
>>I believe 2Mb/s is used for some floppy tape formats.
I still have a NeXT, and the one ED disk it came with.
I can't find the mouse, but otherwise it still works.
> ED floppies came and went so f ast I never got to play with one.
> However I have a few of those Travan backup hacks though they
> didn't seem to stress the FDC any.
-- glen
Barry Watzman
E-Bay. It does indeed look like a standard (non-integrated) floppy
drive with a USB controller (don't have it yet, just going by external
photos). I'll let you know when I receive it.
Barry Watzman
Peter Dassow (remove the NOSPAM. for direct answer)
> That's a CHIP, not a finished product. There are a number of chips that
> familiar with that particular one (and there are others), these were
> intended, for the most part, for use in PCs with 3.5" drives. So there
> are a number of issues to investigate:
>> [...]
Hi Barry,
It wouldn't be wise to develop this from scratch, the main effort would
not be related with driving the floppydisk-controller, instead, you have
a lot of work with the USB driver on PC side.
Until you haven't a skeleton source code for this, do not try to think
about it.
I am sure almost every cheap 3,5" USB floppy could be modified to drive
a 5,25" drive too, this would be cheap enough to be realized.
Unfortunately you have to modify not only hardware, also you have to
modify the USB driver on PC side. As I already said, until you didn't
get any source code, this would be too difficult.
The easiest way is still to take an older PC (like a 486 or Pentium I)
and get also 5,25" floppy drives, like many already said here.
Regards
Peter
--
My new project: Try http://www.z80.eu for CP/M computer infos.