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using XUB with MFM drives

Twospruces

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hello all,
I am thinking about a project to make an improvement to my old Zenith Z-171 lunchbox.
This computer was originally supplied with 2 5.25 floppy drives - no HDD.

I have modified the unit to have two interesting configurations from a storage perspective.

1) HDD via XT-CF card using XUB BIOS and a single CF card as C:, plus a 5.25 floppy and a 3.5 floppy.
2) HDD via WD-XTGEN ISA card and Kyocera KC-20B MFM drive as C:, plus a 5.25 floppy and a 3.5 floppy.

so, I have 2 ways to add a hard disk. The problem I have is that, for configuration (2), I can only boot from Floppy. The Bios is not on it's own able to boot from C:.

I *think* that the only practical way to get this old XT clone to boot from C: is to use XUB. (yah?)

So, I am wondering.... could I use XUB BIOS in conjunction with an MFM HDD?

For example, could this configuration work?
3) HDD via WD-XTGEN ISA card and Kyocera KC-20B MFM drive as C:, plus a 5.25 floppy and a 3.5 floppy.
+ XUB BIOS to enable booting from C:

This would amount to basically adding XUB BIOS along side of the WD-XTGEN BIOS, with some custom hardware. (this is all enabled by custom hardware!).

Feedback much appreciated. thanks.
 

Krille

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So, I am wondering.... could I use XUB BIOS in conjunction with an MFM HDD?

For example, could this configuration work?
3) HDD via WD-XTGEN ISA card and Kyocera KC-20B MFM drive as C:, plus a 5.25 floppy and a 3.5 floppy.
+ XUB BIOS to enable booting from C:

This would amount to basically adding XUB BIOS along side of the WD-XTGEN BIOS, with some custom hardware. (this is all enabled by custom hardware!).

Feedback much appreciated. thanks.
The problem with this is that XUB is made with the assumption that you always want to use at least one drive under control of XUB. In other words, it's not possible to configure the XUB to not try to detect any drives.

(Maybe we should change this? Though this is a pretty rare use case - I think you're the first to request something like this.)

Your options are currently;
1. Use the BIOS as-is and let it go through the motions (try to detect a drive that it will never find etc). This will make the boot process take a lot longer and it will output text you probably don't want ("Master at xxxh: not found" etc).

2. Hack the XUB to skip drive detection.
 

Malc

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2. Hack the XUB to skip drive detection.
I would like to see this as an option to skip primary drive detection in the XUB, The option to skip 'Slave' is already supported. I thought of something similar when playing with Hakfoo's USB boot bios but forgot all about it until now, Yeah it's probably a pretty rare use case but would be useful IMO :)
 

Twospruces

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I see, well, all it really means is that for my config#2, I have to boot from drive A. I can put the DOS itself on C, but need the system to be on A. not the most convenient but whatever.
Config 2 is clearly superior - XUB, CF card....much faster, boots from C etc.

But, I do like that vintage noise of the KC-20B HDD swinging around!

coexistence of an MFM controller and an XT-CF drive (XUB) would be a nice option somehow.
 

Krille

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I would like to see this as an option to skip primary drive detection in the XUB, The option to skip 'Slave' is already supported. I thought of something similar when playing with Hakfoo's USB boot bios but forgot all about it until now, Yeah it's probably a pretty rare use case but would be useful IMO :)
You know, when I added that I originally made it so master drives could be disabled as well. However, there was some kind of side effect (I don't recall what) so to avoid problems I decided to limit the functionality to slave drives only.

My free time is very limited now so I won't be able to do this. If anyone wants to tinker with this then a good place to start would be to disable the calls to DetectDrives_FromAllIDEControllers in Initialize.asm.

coexistence of an MFM controller and an XT-CF drive (XUB) would be a nice option somehow.
Are you talking about the MFM controller coexisting with XUB or with an actual XT-CF controller? Because the latter should be possible (assuming there's room in the machine, available expansion slots etc).
 

Malc

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You know, when I added that I originally made it so master drives could be disabled as well. However, there was some kind of side effect (I don't recall what) so to avoid problems I decided to limit the functionality to slave drives only.
Oh well, It's beyond my skill level, The sun would fall out of the sky and toast us all if i attempted it.
 

Malc

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You know, when I added that I originally made it so master drives could be disabled as well. However, there was some kind of side effect (I don't recall what) so to avoid problems I decided to limit the functionality to slave drives only.

My free time is very limited now so I won't be able to do this. If anyone wants to tinker with this then a good place to start would be to disable the calls to DetectDrives_FromAllIDEControllers in Initialize.asm.
I had a go at this today, I disabled the calls to DetectDrives_FromAllIDEControllers in Initialize.asm. but this broke booting from the flash drive connected to the ISA - USB controller in my XT, After much faffing about with custom builds of XUB and HakFoo's Boot Rom BIOS i seem to have it working but need to do more testing.
 

Malc

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I had a go at this today, I disabled the calls to DetectDrives_FromAllIDEControllers in Initialize.asm. but this broke booting from the flash drive connected to the ISA - USB controller in my XT, After much faffing about with custom builds of XUB and HakFoo's Boot Rom BIOS i seem to have it working but need to do more testing.
So far so good, It's working a treat, i got led up the garden path a bit but it turned out I seemed to have issues with the old flash drives i was using but a firmware update sorted them (Touch wood), Also long delays with different builds of the XUB, The XUB was looking for a supported drive / controller that did not exist, I found the HOTKEY_BAR must be included in the builds to reduce the 25 second delay to virtually a <1 sec delay.

The Tiny build of the XUB would probably be ideal for the job IF it didn't try and boot from the A: drive first and then C:, IF it could be changed to boot from C: first then A:, An 8k ROM could be used to hold the 4k XUB and 4k USB boot rom bios, I looked at the code but couldn't see where / how / what to change.

m1.jpg
m2.jpg
 
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