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FreHD on Model II/12/16/16B/6000 - FIRST ATTEMPT

Lo-tech TRS80 adapter PCBs are due back in stock next few days. I may also look to run the Model II adapter PCB, depending on how any other projects focused on that progress as there is some investment needed from my side to make that happen. It may be easier to just run a special version of the existing board, rather than run with an adapter perhaps.
 
Just curious to see if there has been any progress on this? I'm ready to buy another FreHD, etc. to make this happen. I have two Model IIs needing some HDD love, but I have no HDA... :(

Myles
 
While I'm waiting on my DOM for the Hans01 LSDOS Adapter, I have decided to see if I can get my FreHD working with my Model 16 and Type 2 HD interface. I have upgraded my FreHD to the latest firmware 2.14 but I have not yet reprogrammed the GAL as per @TRS-Ian in post #3 because I don't have a programmer yet. I placed a new ST251 hard disk image on a new SD card and placed it in the FreHD. My tests are positive so far.

When I run the HDIFAC (hard disk interface board diagnostic) test from the Model II/16 Diagnostics suite, all tests successfully pass. This is promising since some of these tests would fail if the Type 2 HD interface was not communicating with the drive controller properly.

IMG_0926.jpg

When I run the HDREL (hard disk data reliability) test, I have tried to enter the correct heads and cylinders for the ST251 (6 heads, 820 cylinders) but the software rejects that combination, so I chose the 15MB default settings (6 heads, 306) cylinders. I then choose to run the single track write test but it responds with "Interrupt not received 2020".

IMG_0925.jpg

So, next step is to reprogram the GAL using the jed file from post #3. I will keep you updated on my progress.

If I'm missing something or royally screwing something up, please let me know. :)
 
Since I will soon be in possession of an MII,

DA question #1: Any progress anywhere in getting FREhD working with the type 2 HDC?

DA question #2: @pski, any guesses as to what happens if a M3SE is plugged into the type 2 HDC instead of a FREhD?

Mike
 
MikeModifed said:
DA question #1: Any progress anywhere in getting FREhD working with the type 2 HDC?
Click to expand...

Wow, I completely forgot about the fact I was working on this! Thanks for reminding me. The podcast and VCFE have been dominating my free retro time lately. I will get back into this after VCFE. I bought the chip programmer at least.

MikeModifed said:
DA question #2: @pski, any guesses as to what happens if a M3SE is plugged into the type 2 HDC instead of a FREhD?
Click to expand...

I have not tried it yet. Again, its on the plan to try soon. I'll use the same Model 16 as I will use for the FreHD so I will try to get both done when I pull that machine off the shelf and put it on the test bench.
 
pski said:
Wow, I completely forgot about the fact I was working on this! Thanks for reminding me. The podcast and VCFE have been dominating my free retro time lately. I will get back into this after VCFE. I bought the chip programmer at least.



I have not tried it yet. Again, its on the plan to try soon. I'll use the same Model 16 as I will use for the FreHD so I will try to get both done when I pull that machine off the shelf and put it on the test bench.
Click to expand...

Pete, did you ever get a FreHD working with the type 2 HDC?
 
Once I found suitable MFM HD emulators for the M2 in the DREM and the Gesswein MFM Reader, this fell off of my radar. There is still probably a need for a Model II FreHD though. I just don’t know when I’d get around to it. It will be a huge effort to write M2 TRSDOS and XENIX drivers since we don’t have source code or knowledge of how to write those drivers. It will have to be reverse engineered. Since we already have the Hans DOM solution for LS-DOS and CP/M on the M2, the urgency for a FreHD is also diminished.

But, I hear Mav has a working M2 now, so..... ;)
 
I personally think that the core issue is the lack of proper (in the eyes of the drivers on the Model II operating systems, that is) IRQ emulation in the xtrs WD1000 emulation code upon which FreHD is based. The Model II series uses mode 2 interrupts, and the HDC adapters (types 1, 2, and 4) that actually interface to the Model II bus all have Z80 CTC chips on them to generate the mode 2 vector when the WD1000 board (or circuitry on the interface, in the case of the type 4) generates its IRQ. As always, I reserve the right to be wrong, but that is my educated guess, based on Tandy's known reluctance to spend one penny more than absolutely necessary; the Z80 CTC wouldn't be there if no mode 2 interrupts. With FreHD's primary audience being the Model I/III/4 crowd IRQ emulation isn't a big deal, since, to the best of my knowledge, none of the I/III/4 OS hard disk drivers use the IRQ capability, preferring to use programmed I/O. This is why the LS-DOS 6.3 drivers work ok on the Model II without the proper Z80 CTC sitting there.

With xtrs emulating the I/III/4, there wasn't any reason to fully test the WD1000 emulation's IRQ response, even though the DRQ is asserted after a read or a write.

Now, I haven't dug deeply enough in the FreHD code in the PIC to know whether Fred implemented full WD1000 IRQ emulation or not, but this is where I would start looking if I were inclined to spend the time checking. It should be possible to instrument the FreHD code to send debugging information out the serial port, so you could do command traces for debugging purposes.

In a nutshell, it would be easier to modify FreHD to work with the Xenix and TRSDOS drivers than the other way around, since FredHD is fully open-source.
 
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Correct, lowen. Man, I need to spend more time re-reading this thread. I forgot how much we had already looked into this. Tonight.
 
Yeah, I see that I already did look into the FreHD code in post #20. So someone needs to write the code for the PIC on FreHD to emulate the IRQ, and make sure it's wired to the correct pin on the interface.
 
lowen said:
Yeah, I see that I already did look into the FreHD code in post #20. So someone needs to write the code for the PIC on FreHD to emulate the IRQ, and make sure it's wired to the correct pin on the interface.
Click to expand...

This is correct. I never could implement the interrupt since I don't have access to a model 2... and nobody could ever provide me with traces taken from a logic analyzer... But there is provision to add the IRQ handler (the GAL has one or two IO pins left). At the same time, it'd be good to fix some output signals which should be open-collector... and maybe use a better microcontroller, but my goal (at that time) was to just hack something quickly, I never thought other people could be interested in this project :)

-Fred
 
veco said:
This is correct. I never could implement the interrupt since I don't have access to a model 2... and nobody could ever provide me with traces taken from a logic analyzer... But there is provision to add the IRQ handler (the GAL has one or two IO pins left). At the same time, it'd be good to fix some output signals which should be open-collector... and maybe use a better microcontroller, but my goal (at that time) was to just hack something quickly, I never thought other people could be interested in this project :)

-Fred
Click to expand...

A FreHD Mk. 2?
 
I hate to ask, as I would like a "proper" FreHD for the Model II that works with all OS options, but would it be possible to use the current FreHD without IRQ support under LS-DOS? It sounds like LS-DOS isn't making use of interrupts anyway, and that's all I really intend to use on the Model II at this point. My dilemma is that I don't currently own a FreHD, I would like to get one eventually for the Model I,III, and 4P; but I also own a Model II with no software/media, so it would be perfect if I could share the same FreHD between them all. So do I wait for a new rev that has IRQ support (with no guarantee that would ever happen) or do I buy now and hope that it can some day work with the Model II? If I could format the SD card on the Model 4P and at least make use of it under LS-DOS on the Model II, then it might not be worth the wait for IRQ support, at least for me.

Also, I understand that some Model IIs don't support hard drive booting, is there any easy way to determine which version I have?

If IRQ support wasn't needed, could a simpler interface board be used to connect the FreHD to the Model II bus? Would the additional RAM still be needed?
 
Thanks Pete,

I guess I should have been a little more clear though. I currently have no way to boot the Model II. My thinking was that I might be able to avoid having to buy 8" media and either find a way to make my PC write a disk image, or having someone ship me a boot disk, if I could just boot the machine directly off of the FreHD. There was a collector just north of me in Vancouver Washington that has/had a Model 16B or 6000 (can't remember which), maybe I will try to track him down and start there.

-Dan
 
Another option for booting the Model II is to use a floppy emulator such as a Lotharek HxC. I've booted my Model II and my Model 12 from disk images with one, after hooking it up with an adapter board that I made. The adapter board isn't strictly necessary; you can wire up your own adapter cable if you prefer. I don't sell the adapter board, but it's easy to make your own after ordering bare boards from OSH Park.
 
NF6X said:
Another option for booting the Model II is to use a floppy emulator such as a Lotharek HxC. I've booted my Model II and my Model 12 from disk images with one, after hooking it up with an adapter board that I made. The adapter board isn't strictly necessary; you can wire up your own adapter cable if you prefer. I don't sell the adapter board, but it's easy to make your own after ordering bare boards from OSH Park.
Click to expand...

I've built one of your adapters. It's much easier than making the cable.
 
@dano: I have had my MII working with an HxC which doesn't immediately help you. However I'm in NE Portland (vic I-84 & I-205) and have a pile of bootable 8" disks. Do you have any non-booting disks to swap?

BTW: ATT my MII is in storage providing a "flat spot" to pile other stuff on.

Mike
 
The HxC isn't a bad idea, but in a way it takes me back to the same dilemma: If get a FreHD for use with the Model I/III/4, then I would love to use it with the Model II instead of buying another storage device. That said, if all else fails then I could always use a 5.25" drive for the same purpose I suppose. Got lots of those. Either way I am thinking of buying one of the adaptor boards, I think it would look better than anything I could prototype, and it would avoid any unneeded mistakes.

Mike: I would love to take you up on the offer, I just need to dig trough the disks that came with the computer and see what I have. Everything is stored away as we are in the process of moving. I'll check as soon as I can and then send you a PM.

Thanks for the link to the Model II archive project, it's nice to see others taking an interest in these machines, when time allows I'll look though my disks and manuals and see if there's anything I can add.

-Dan
 
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