How to exchange files between a Model II and a Model 4p

It must be possible to exchange files and data between a Model II and a Model 4P
This must be possible with LS-Dos 6.3.1A for the Model II

I have tried to do this, without any succes, does anybody know how to do this ?

What I have done so far.

I have made a bootable 8" sssd floppy with LS-Dos 6.3.1A.
I can boot the Model II with this disk.
I have interfaced a 5.25 HD Floppy as drive 1
I have reduced the speed of the floppy to 300 t/min.
I can easily do a hardware swap between drive 0 and drive 1

The results so far.

I have read all the documentation about this subject.
I can copy the system from the 8" drive to the 5.25" drive.
I can swap the drives and boot the computer from the 5,25" disk.
I can read and write data from and to the 5.25 drive (formatted as a 8" drive with 77 tracks).
If I use the device driver FLOPPY/DCT and set drive 1 to option 0, a 5.25" drive.
Then I can format the drive as a model 4 disk (SSSD 40 tracks)
I have used all other options too, like DSDD, SSDD, without any problem.
I get no errors, but if I try to write something to this disk ( used as a mode 0 floppy), I always get an error about a
corrupted directory.
I can use the free and device commands for the drive but no DIR.

Has anybody a suggestion ?

Hans01

Serial ports?

Parallel ports?

Either is a possibility.

@Stone

Stone said:

Serial ports?

Parallel ports?

Either is a possibility.

Click to expand...

Yes I know the other options, but

Serial communication needs a special cross cable and software and
is v-e-r-y slow.

The same problems with parallel communication, as far as I know, there is no software for the model II

Al last, the possibility is build in the LS-Dos software so it should work.

Hans01

Did you read somewhere in the LDOS docs that this could easily be done? That seems unlikely to me.

The Model II FDC can write 250 kbps FM or 500 kbps MFM. The Model 4 can read 125 kbps FM or 250 kbps MFM. These are four distinct formats: 250 kbps FM is not the same as 250 kbps MFM.

If you can get the drive to spin at 360 rpm when connected to the Model 2 and 180 rpm when connected to the Model 4, then data written by the Model 2 as 500 kbps MFM would be played back to the Model 4 as 250 kbps MFM. You would likely still need to write custom drivers for the Model 4 to cope with the fact that tracks would be twice as long as expected.

@ Hans01

something to try.
Format a 5 1/4 " floppy as SSDD / SSSD 40 track on the Model 4p and then put it in the Model II and see what happens with file transfer.
Ps Thats a lot of testing you have done.

Good Luck

Ray W

@Ray

something to try.
Format a 5 1/4 " floppy as SSDD / SSSD 40 track on the Model 4p and then put it in the Model II and see what happens with file transfer.

Click to expand...

That was indeed the next step to try.
The same result. If I do a DIR or FREE command no problem. As soon as I write something to the disk the directory is ruined.
I have try to read a 8" format on a 5.25" floppy on the Model 4P, that is not possible.
There must be an error in the FLOPPY device driver for the Model II.
I have used the LS-Dos 6.3.1 version and the rewritten Tim Mann's 6.3.1.a version but the same result.
I have used the HxC emulator with many different file formats, but the same problem.:-(

For the users of a Model II, the 6.3.1.a version is much better than the 6.3.1 version, it has a lot more software in it and some
updated versions of the sys files. (available in SS and DS versions)

Ps Thats a lot of testing you have done.

Click to expand...

Yes, I like these old Tandy's and want to restore them as good as possible.
B.t.w. I had to fix three dead key's on the keyboard. I have replaced the foam inside the key's.
Yes, it can be done, using a special glue film.

Hans01

Hans01 said:

It must be possible to exchange files and data between a Model II and a Model 4P
This must be possible with LS-Dos 6.3.1A for the Model II
...
Has anybody a suggestion ?

Click to expand...

The Model II's FDC is clocked for the 8-inch formats where SD is 250kb/s and DD is 500kb/s. The Model 4P's FDC is clocked at half that rate where SD is 125kb/s and DD is 250kb/s. While it would seem like the SD 8 inch format at 250kb/s and the 5.25 inch DD format at 250kb/s would work, in reality it won't due to the difference between MFM and FM coding and the double clock rate of 8 inch SD relative to 5.25 inch DD.

In order to make this work you would have to do one of the following:
1.) This is the easiest, but doesn't use a TRS-80 to do the transfer. You simply use a PC that has both an 8 inch and a 5.25 inch drive with the standard high-density-capable controller. This is by far the easiest route to do disk-based transfers. Do note that bootable disks on the Model II have a SD track 0 and so reading those disks on a PC requires and FDC that can reliably read SD.

2.) Modify the Model II's FDC to have an output port that can switch the clock going to the FDC chip between the normal 2MHz and the 5.25-compatible 1MHz. The difficulty here would depend upon which version of the FDC board you have (or if it's a Model 12/16B/6000, which uses a rather different FDC chip). The part that might cause issues is the data separator; this would in theory be easier on the 12/16B/6000 than on the II/16, since the 2797 chp used in the 12/16B/6000 has its data sep built-in, as far as I remember.

3.) Modify the Model 4P's FDC to have an output port that can switch the clock going to the FDC chip between the normal 1MHz and the 8 inch-compatible 2MHz. There are two difficulties here: the gate-array 4P uses the 1773 FDC chip and might not be able to clock that high; the non-gate-array 4P's FDC's data sep circuits might not work at the double clock rate. EDIT: Do note that the Model II has a Z80 DMA chip for DD 8 inch transfers for a reason; a 4MHz Z80 may not be able to keep up with a 500kb/s data rate without some work. Although I seem to remember 8 inch capable FDC boards being sold by Aerocomp and others back in the day that advertised 8 inch capability on the Model III and the non-gate-array desktop Model 4.

Options 2 and 3 will require you to reassemble or patch the floppy disk driver in LS-DOS 6.3.1 to handle mixed data rates. The current FDC driver for LS-DOS 6.3.1 for the 4P is well-documented and would make the modification a bit easier than the equivalent for the Model II, as the LS-DOS 6.3.1A sources for the FDC driver for Model II LS-DOS 6.3.1A are not publicly available as yet. The FDC driver is very different between the two, since double-density transfers on the Model II require use of the Z80 DMA chip that the Model II series possesses.

Now, if you have an HD interface board in the Model II, you could in theory use a FreHD to do the transfers, with the modified PIC firmware that has been mentioned in this forum.

@Iowen

Thank you for the wel documented explanation of the problems.

I have some remarks about your answers:
On my Model II I can setup a 5.25' disk as drive :1.
Use device driver Floppy and choose option 0 (5.25 drive)
Now I format this drive as SSSD with 40 Track's. The default format.
I get no errors during this format and the directory is written at track 20.
If I execute DIR :1, I see the directory information.
Free shows the right disk info.
Device shows the right info.

But if I write or copy a file to this disk I get an error.
Why this error as I can format the disk without errors.

If I use the default 8" device driver for the 5.25" diskdrive,
and format the disk as SSSD with 77 track's there are no problems.

I can use the 5.25" drive just like an 8" disk.
I can even boot the system with this disk.

I assume that Misosys, who claims many times the possibility to exchange software between
a Model II and a Model 4, should have tested it, so I assume the problem with the clock speed is solved in their perfect software

My hardware is as follows:

Model II
Old model FDC with modified cable to support 5.25" drives and 8' drives, with external termination.:?
I have no harddisk controller in the Model II
The 5.25" floppy is a HD 1.2 Mb drive, running at 300 rpm.

The Model 4P
It has A FreHD and a Lo-Tech IDE interface
It is a GateArray version


Hans01

Hans01 said:

@Iowen

Thank you for the wel documented explanation of the problems.

I have some remarks about your answers:
On my Model II I can setup a 5.25' disk as drive :1.
Use device driver Floppy and choose option 0 (5.25 drive)
Now I format this drive as SSSD with 40 Track's. The default format.
I get no errors during this format and the directory is written at track 20.
If I execute DIR :1, I see the directory information.
Free shows the right disk info.
Device shows the right info.

But if I write or copy a file to this disk I get an error.
Why this error as I can format the disk without errors.

Click to expand...

When you changed the disk to 300rpm, this increases the number of sectors that will fit on a track. When you then formatted the disk, the format routine only formatted the number of sectors per track that actually fit for 360RPM HD operation, and thus the whole track is never actually overwritten (source is out there for the FORMAT/CMD utility, so you can read the source and see the build-up of the track buffer for passing to the FDC's WRTRK command). The verify operation uses special routines that apparently are not bothered by any extraneous data on the track, but the OS's primary R/W routines are, and will throw an error.

I will have to look at the source that I have disassembled for the FDC driver to see what it actually does if the size is set to 5.25 inch. While it's not the 6.3.1A source code, the LS-DOS 6.2 sources are out there in several places; the Model II FDC driver module from LS-DOS 6.2 is attached. A quick skim shows that the drive size info in the DCT (DCT+3, bit 5) is never accessed by the driver, meaning that the LS-DOS 6.2 for Model II/12 FDC driver simply does not know how to use a 5.25 inch drive. Whether the 6.3.1A driver has logic to deal with a 5.25 inch disk or now I have not yet verified.

If I use the default 8" device driver for the 5.25" diskdrive,
and format the disk as SSSD with 77 track's there are no problems.

I can use the 5.25" drive just like an 8" disk.
I can even boot the system with this disk.

Click to expand...

This is at 360RPM and HD media, correct? This is the correct behavior, since an HD 5.25 drive is essentially an 8 inch drive in terms of its format.

I assume that Misosys, who claims many times the possibility to exchange software between
a Model II and a Model 4, should have tested it, so I assume the problem with the clock speed is solved in their perfect software

Click to expand...

LS-DOS 6.3.1 (and LS-DOS 6.2 before it) for the Model II are nowhere close to perfect; there are a number of bugs, some of which are related to hardware bugs. According to a source who was at one time inside of Tandy, a number of quirks in the Model II hardware were not being handled correctly by the LSI code (prior to the acquisition by Misosys). The Model II/12 LS-DOS was always an AS-IS product; I actually purchased it in 1990 myself and the AS-IS nature was in the printed documentation as I recall.

The software compatibility was limited to SVC-level coding, and the README/DOC file on the LS-DOS 6.3.1 for Model II disk mentions that. It does not mention how to get programs from one system to the other, though.

My hardware is as follows:

Model II
Old model FDC with modified cable to support 5.25" drives and 8' drives, with external termination.:?
I have no harddisk controller in the Model II
The 5.25" floppy is a HD 1.2 Mb drive, running at 300 rpm.

Click to expand...

This FDC board has no way to programmatically change the FDC clock. There is a jumper on the oldest card that either straps in or straps out a divide by two for supporting a CPU clock of either 4MHz or 2MHz. To get a 1MHz clock to the FDC, you would have to run your CPU at 2MHz; to be able to read with a 2MHz FDC clock (for the 8 inch drive) and write with a 1MHz clock you would either need a programmable divide by two or a way to change the CPU clock rate on the fly. The revised FDC printer card has a set of jumpers to additionally select either a 2MHz or a 1MHz clock (jumpers P, Q, and R). But you would need additional logic to allow the driver to switch the hardware between these two.

This is documented for the older FDC in the Model II Technical Reference, and for the newer FDC in the Revised Floppy Disk Controller supplement (MODII_12_TRM_FDC_REV.pdf on the various archives).

The driver can't do what the hardware will not allow. If you have the later Model II FDC the divide by two to get 1MHz is already there at least, and you would just need to appropriate a bit in the drive select latch port (which would require another chip; the revised FDC board at least uses a six-bit latch (74LS174) here, and all six bits are in use).

Even if formatting/writting a 5.25 disk SSSD 40 tracks with the HD drive did work on the Model 2, I doubt that the same diskette would work in the Model 4. Unless the M2 driver was double stepping the tracks using the HD drive, the disk would only be using half the media.

Yes, In a PC/AT, the HD drive can be used for DD media. But it's still a 80 track drive and PC dos must slow the RPM to 300, use a different data rate, and double step the tracks to effectively get only 40 tracks on the disk. I don't think the M2 can do this.

Why not use try a normal 40 track drive with the M2 instead of the HD version?

Rick

@ Hans01

Yet another thought, can you erase the floppy using an old magnet out of a hard drive or use a "Bulk Eraser",
as there may be some residual info left on the media.
The 40 Track Drive looks like a good possibility,(are you able to choose the number of tracks in the Model II during format).
Good luck

Ray W

@Iowen

Thanks again for pinpointing the problems.

As I only want to exchange a few files. it is too complex to find a good solution for this problem.
I don't know if Misosys is still alive, but if they are, they should pick up the problem.

If everybody try to make his own solution for the problem, it would be a bad way to go.
Some additional documentation would be nice too.

At this moment I have only a few files to exchange and finding a solution would take much more time
then export the files and import them on the Model II.

Thanks a lot for all the time and information you contribute to this subject.

Hans.

@lisa2

You are absolutely right about the 40 tracks problem, but I have a 80 track drive in my Model 4p.
At the moment I don't have a spare 40 track drive.

As the Model II could not read his own formatted disk, there was no need to solve the 40 / 80 track problem.

Thanks for the information

Hans01

@Audronic

Hi Ray, thank you for remembering the old "Bulk Erase" trick.
You can always use this trick when you get a "Track 0 unusable" error too.

But I have used some fresh new disks right out the box.

Please also read my answers to Iowen and Lise2

Hans01

Hans01 said:

...
I don't know if Misosys is still alive, but if they are, they should pick up the problem.

Click to expand...

Misosys was dissolved over 20 years ago. The Model II/12 LS-DOS 6.3.1A was one of their last products.

If everybody try to make his own solution for the problem, it would be a bad way to go.
Some additional documentation would be nice too.

Click to expand...

Correct on both points. For my own purposes, I use a Catweasel in a PC running Linux and Tim Mann's cw2dmk tools to make image of 8 inch disks. I use a DBIT FDADAP for the adapter so that I could write with my 8 if needed (The FDADAP properly drives the TG43 signal for reliable writing on the 8-inch drive). Once I have the .dmk, I read it using the 8 inch driver for xtrs, booted into LS-DOS 6.3.1 for Model 4. I have never tried direct 8 inch hardware access with the xtrs 8 inch driver, only DMK image access, which works fine.

For Model II emulation (to actually boot and run Model II OS's) I use MESS. This brings up its own image format issues, which I've not resolved to my satisfaction as yet.

I am working on a restoration of the LS-DOS 6.3.1A for Model II/12 sources so that if someone were so inclined they could pick this up and develop a reliable mod to do good data interchange. I have quite a bit of work to do, but most of it is stalled while I work on the MESS image issues I've been seeing (basically, highly unreliable disk writes at the moment; read-only disk I/O works pretty well, but MESS only supports writing on certain formats, and DMK isn't one of the ones supported in the version of MESS I'm working with). To compound the issue, MESS recently changed to using SDL 2.x, and until very recently I wasn't running a Linux distribution that supported SDL 2.x development (I am now, but haven't had time to resync my development MESS tree). The goal is of course to build a set of self-hosting disk images so that LS-DOS 6.3.1 could be reassembled on Model II hardware (or emulated hardware).

So the data interchange with a Model II is something I've been doing for a while; I've just been using an emulator to do it. A good 8 inch FDC for the 4P would be a possibility, if someone were to build such a beast. This is non-trivial. However, at 4MHz it is just possible that the Z80 could do the Model III/4-style disk I/O at the doubled data rate; the only way to find out would be to build the mod (selectable clock input to the FDC chip), write a patch to the FDC driver, and try it out. This would be the easiest mod, since reassembling the source for Model 4 LS-DOS 6.3.1 is something that is pretty easy to do, thanks to the hard work of Frank Durda IV and of Pete Cervasio. Pete's source packages are easier to find, since Tim Mann hosts them. Frank's sources could at one time be obtained through MADsoft, but that product is no longer sold. The sources themselves are on Frank's site, nemesis.lonestar.org, but you have to grab them one at a time.

Neither of my 4P's is a gate-array machine, though, so I can't develop this mod. The gate-array machine uses a 1773 FDC chip, which is electrically quite different from the 1793 FDC used in the non-gate-arry machine. It's supposed to be software-compatible, but it is not 100%, which is documented in a couple of the Misosys Quarterlies (Frank Durda IV found the bug), which are available for download from Tim Mann's site.

@Iowen

Hi.

>>> Misosys was dissolved over 20 years ago. The Model II/12 LS-DOS 6.3.1A was one of their last products.
It's a pity.

>>> I use a Catweasel in a PC running Linux
I have a HxC floppy emulator from Lotharec, I build a floppy cable for the 50 pins extension bus.
I have the HxC which can emulate 2 drives at the same time.
I moved the internal 8" drive to position :1 and one of the HxC drives to position :0
The HxC can read and write IMD files, now I can boot my Model II with a bootable system image and easily format a 8" disk an
convert the system to the 8" drive.
Now I restore the default drive configuration and can boot from my fresh 8" disk.

>>> For Model II emulation (to actually boot and run Model II OS's) I use MESS.
I have the latest MESS version running under Windows 7, but it is not very useful.
LS-Dos 6.3.1.a mostly doesn't boot or sometimes twice.
I can not add a second drive.
The keyboard emulation is hopeless.

I don't like to modify the hardware of my Model II or Model 4P, I would like to keep the computer as close as possible to the genuine systems.
Patching an eprom or expand the floppy interface with two extra drives and the FreHD and Lo-Tech adapter are for me the maximum.

I'll take a look if it is possible to interface the Lo-Tech on the Model II, there are all the signals on the 50 pins bus connector and there are
harddisk drivers in LSDos 6.3.1.a

Hans01

Hans01 said:

...
I have a HxC floppy emulator from Lotharec, I build a floppy cable for the 50 pins extension bus.

Click to expand...

Ah, now you might have something. It might just be possible to write a DCT entry for the 4P that would read from an HxC emulated 8 inch drive but at 250kb/s. Or you might be able to patch the LS-DOS 6.3.1 for Model II DCT's to allow writing to a 5.25 formatted image, but at 500kb/s. It might be just as simple as setting the right numbers in the DCT (I'll have to refresh my memory as to how to patch those in-memory).

I have the latest MESS version running under Windows 7, but it is not very useful.
LS-Dos 6.3.1.a mostly doesn't boot or sometimes twice.
I can not add a second drive.
The keyboard emulation is hopeless.

Click to expand...

All of these are true; MESS Model II emulation is definitely a work in progress. However, it is questionable as to the exact nature of the bugs, whether it's in the emulation or in LS-DOS (I remember the initial boot into LS-DOS on an actual Model 12 sometimes not working properly, too; it seemed like that if LS-DOS double-booted the keyboard would work, but if it didn't you'd have no keyboard).

Now, what would be very useful to the MESS team is to get a ROM dump from the keyboard controller IC (inside the keyboard) to make the emulation better.

I'll take a look if it is possible to interface the Lo-Tech on the Model II, there are all the signals on the 50 pins bus connector and there are
harddisk drivers in LSDos 6.3.1.a

Hans01

Click to expand...

So you do actually have the hard disk interface (not controller; interface) in your Model II? The 50-pin expansion bus version that is compatible with the 50-pin Model III/4/4P bus? Without the HD interface card you don't have the expansion bus.

@Iowen

Some updates:

>>> It might be just as simple as setting the right numbers in the DCT
Indeed, some of the options you mention are worth to investigate it.

But I discovered something remarkable:
I have taken a drive from a model 4p and connect it to the Model II.
Now if I try to format it as a 8" disk the disk is checked but gives an error
(rotation speed ?). But when I setup the drive as a 5.25" disk and try to
format it, I get a no disk error.
It looks to me that the 6.3.1a version is written for the new type of floppy
interface. They have a special 34 pins connector for the 5.25" drives.
I think that the hardware for this port is different.
(I have the old version with only one 50 pins port)

>>> it seemed like that if LS-DOS double-booted the keyboard would work
Yes, indeed, after 5 or 6 soft resets the system boots and has a working keyboard.

>>> So you do actually have the hard disk interface (not controller; interface) in your Model II?
Yes and no. I have a bernouiili interface card in my computer, but no bernouilli box.
The card has a 50 pin connector and my guess is that it is a harddisk interface.
I'am searching for more information about the card and connector, but without any luck.

Hans01

Hans01 said:

But I discovered something remarkable:
I have taken a drive from a model 4p and connect it to the Model II.
Now if I try to format it as a 8" disk the disk is checked but gives an error
(rotation speed ?). But when I setup the drive as a 5.25" disk and try to
format it, I get a no disk error.
It looks to me that the 6.3.1a version is written for the new type of floppy
interface. They have a special 34 pins connector for the 5.25" drives.
I think that the hardware for this port is different.
(I have the old version with only one 50 pins port)

Click to expand...

The newer FDC has a hard jumper to select either 1MHz or 2MHz for the FDC clock. It would seem that the possibility of using it with 5.25 drives was considered, but even then it would be an 'either 5.25 or 8 inch, but not both at the same time' since the jumper can't be switched under software control, and that's what has to happen to be able to support both 5.25 double density at 250kb/s and 8 inch double density at 500kb/s on the same FDC.

I have a bernouiili interface card in my computer, but no bernouilli box.
The card has a 50 pin connector and my guess is that it is a harddisk interface.
I'am searching for more information about the card and connector, but without any luck.

Hans01

Click to expand...

The Bernoulli interface is not the expansion interface you want. According to Frank Durda IV, in a message to comp.sys.tandy in 2000, the 8 inch Bernoulli interface was a pseudo SCSI interface. SCSI is, after all, 50 pins in the original version, and according to Frank (who wrote the drivers for it) it was a DRAFT version of the standard that was used. It is pretty close to SCSI, though, but finding driver support would be rather difficult, if you wanted to use an old narrow SCSI hard disk for data portability. Now, that would actually work, but you'd need the SCSI drive and the Misosys MSCSI interface for the 4P along with drivers to make it work.

@Iowen

Hi.

As I'am not sure about the board, I put a request on the forum.
I hope somebody recognise the board.

Please will you take a look at the pictures.

Hans.