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FreHD, Model 4P, MODELIII/ROM and timing isn't right in Model III mode.

T

Tibs

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Dec 10, 2016
Messages
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Using the MODELIII/ROM that comes with the FreHD for a 4P image (Updated ROM too), when in system (FAST) it does not properly adapt to the faster interrupts. It runs the clock at half speed (TIME (CLOCK)). Using a MODELIII/ROM from various disks work or just not having FreHD connected.

I know there were some hooks and changes to the Model III ROM, and looked at the source for the FreHD and I cant see why it's happening. Its almost like LDOS is doing the math twice for the 60 (4mhz) interrupts vs 30 (2mhz).

Another data point, with the M3SE connected in the same Model 4P it works fine, so I do not beleive the ROM in the 4p is the cause.
 
I haven't seen this with my Model 4P.

I've booted from the TRSDOS hard disk image for the Model 3 and played Model 3 games just fine.
I've also booted from Model 3 floppy disks and used them without problems - with the FreHD attached.
 
Do you have the updated ROM that lets you boot from the FREHD? It works with the floppies fine, it's just the MODELA/III in the FREHD that seems to be affecting the clock.
 
What rom are you using?
All of this is from my (fading) memory but I think the problem is with the frehd.rom file that lives in the root directory of the SD card.
It will only work with one version of MODELA/III and that version is a bit iffy. Newdos definitely doesn't like it yet Newdos will run perfectly with other versions of MODELA/III.
An option might be to modify frehd.rom so it uses the roms MODELx/III loader and that will give back the ability to load MODELA/III ModelB/III etc.
The FIX rom will then load the MODELx/III file from the FreHD.
Not as fast as frehd.rom but should load it in under a second.
I'll leave these mods for someone else;)
 
I'll give that a shot, Just a few bytes at the end are different - before the copyright message which is also different. Probably gonna disassemble and see what that code is as well, curious.
 
So that particular ModelA/III just loads ModelA/III and goes to the Floppy drive when I pick LDOS 531 from the FreHD menu. Doesnt boot the Model III OSes directly from FreHD.

To be clear - I have the Model 4P Diskless ROM from Ian, and the 4P Image that lets you boot Model III OS from the menu. The ModelA/III in that image has been modified quite a bit to work that way and its quite different than the included ModelA/III you have and one I have.
 
Just 4-the-hell-of-it I checked some of the versions of MODELx/III I have and a few I got off the net, all-up 21.
After running them through HXD I narrowed that 21 do to 6.
Some only have a byte difference and one has an EOF error in the Dir.
The version I have on my 4P SD card is identical to the version that is on my original LSDOS631F disk, the LSDOS631H disk from Tim Mann's site and the version on Ian's site.
Need to get my 4P out of storage and check things.
 
I'll pull the one from Tim's site and drop it in the Model 4P card. Last one I tried from a MODELA/III disk (orignal) it just booted to the floppy and ignored the mounted image.

And yeah, Im leaving it in the root of the SD Card. Its boots everything fine and all works, just the clock runs slow in fast in Model III mode. (tons of source code out there shows how that should work and if I had not been looking at z80ctl source code all week I would remember what it was).

Who knows, maybe I've got something bad here. I do have a ton of them scattered about.
 
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