JR-IDE Rev.B & Rev.C + RPi-Zero Module

Hardware questions and modifications

Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby ianoid » Thu Nov 03, 2016 6:13 am

I'd be into a Jr. IDE fully assembled. Hope I'm not too late. I'd take the $100 everything build. Please PM me if this is possible with any instructions or payment needs, etc.

Thanks,

ian
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby KenG » Sun Nov 06, 2016 2:11 pm

I got my Rev.B jr-IDE yesterday. In a lucky coincidence, the DOMs were in the mailbox with it. First problem was the DOMs didn't support power through the interface. Dug out an old power cable splitter and then the Jr-IDE recognized the DOM. Took a few tries with fdisk but I got it partitioned. 360mb, 740mb, and 740mb partitions. Formatted them and ran sys on c:drive. Wouldn't boot to it, but would if first was from a:drive. I remembered something about needing to patch the boot sector. Downloaded patchdos, it didn't work. Printed Mike's instructions on using debug and followed them. SUCCESS!

I am still copying things over and tweaking the config.sys and auto executives.bat files, but it works great. I do have a question for Alan though. If you let "Prees ESC for boot menu"time out it tries to boot from A:, I would have thought it would be set to default to C:. Not a big deal, just curious why it was done that way.

It is a wonderful piece of equipment for the Jr though.
Enhanced PCjr with a jr-IDE (1GB DOM) and a parallel port side car with a compact flash reader and backpack 1.44mb floppy attached. Tandy video mod.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby Trixter » Sun Nov 06, 2016 2:34 pm

What version of DOS were you using that PATCHDOS didn't work with? If it's a bug in the program, I'd like to fix it.

(Also, why 3 partitions of those specific sizes?)
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby KenG » Sun Nov 06, 2016 4:04 pm

I am using a version I got from jmetal88. Not sure if it is MS-DOS or PC-DOS. But it is 5.0. Mike's instructions worked perfectly. Could it have to do with using a DOM instead of a hard disk? Don't know why it would.

I just re-read my last post. I mis-stated what I did. I created a 260mb primary DOS partition and a 740mb extended DOS partition. Then I created two 370mb logical drives in the extended DOS partition. I was trying to keep the first dir lag from being too long.
Enhanced PCjr with a jr-IDE (1GB DOM) and a parallel port side car with a compact flash reader and backpack 1.44mb floppy attached. Tandy video mod.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby alanh » Sun Nov 06, 2016 8:43 pm

I'm not sure about the behavior of the boot menu. I don't fully understand it myself like why it repeats. Mike should know.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby Brutman » Sun Nov 06, 2016 9:03 pm

The default for any PC type machine is to boot from drive A. I did not want to deviate too far from existing BIOS behavior.

As for repeats, you should only see a repeat of the boot menu when using jrconfig. It boots first to fix the location of the video memory window, and then it boots again to load DOS once the window is moved. Which is why the machine looks like it boots twice.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby KenG » Mon Nov 07, 2016 4:17 am

Ok, thanks for the explanation. I knew why the double boot. I think that if there isn't a bootable disk in A:, it will boot from C:, it just takes a while since it happens twice. Would there be a way to store the boot information from the first boot somewhere and go straight in without pausing the second time? Not a big deal, just curious.
Enhanced PCjr with a jr-IDE (1GB DOM) and a parallel port side car with a compact flash reader and backpack 1.44mb floppy attached. Tandy video mod.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby KenG » Mon Nov 07, 2016 6:50 am

OK, I tested it this morning. If I do nothing it does boot to C:. I think the only difference from a PC of that era is the double boot and menu option. I know the menu option is necessary if you want to get to cartridge basic.
Enhanced PCjr with a jr-IDE (1GB DOM) and a parallel port side car with a compact flash reader and backpack 1.44mb floppy attached. Tandy video mod.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby Brutman » Mon Nov 07, 2016 8:45 am

The double boot is under the control of jrConfig, so short of reverse engineering that and re-writing it, that has to stay. jrConfig squirrels away some information between boots but it's not coordinating with the BIOS in any way, so the second boot looks for the floppy drive even though it's redundant. The only way out of that is to set an option on the jrIDE to set the C drive as the default, and skip trying to boot from A entirely. The way I see it, booting from hard drive is infinitely faster than booting from floppy, so what we have is good enough. (I'm a big believer in keep it simple.)

On a happier topic, Alan and I spoke last week and he gave me some details on the RPi-Zero module and how it will interface to the jr. Besides reminding me how out of date my lower level skills are getting it did make me uncomfortably excited; there is a lot of potential when you decide to embed a small Linux machine as a dedicated co-processor.

One of my first tasks will be to write a DOS packet driver that will pass packets through the IDE interface to the RPi-Zero, letting it do the networking. While we can get networking already on a jr, having the RPi-Zero on board will let you use commonly available USB to Ethernet or USB to WiFi adapters.

Another possibility is a DOS block mode device driver that lets you add logical drives on the fly. So you'd have a 'real' hard drive emulated on the IDE interface, and additional drive letters supplied/backed by the RPi-Zero.

There are all sorts of fun networking tricks we can do to. This is going to be a great project.
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Re: JR-IDE Rev.B & Rev.C + RPi-Zero Module

Postby KenG » Tue Nov 08, 2016 6:50 pm

I removed my Quadram expansion chassis when I installed the Jr-IDE. The only thing it was giving me that the Jr-IDE doesn't have was the 3.5" 720k drive. I got my 1.44mb 3.5" backpack drive yesterday, but had no time to install it. I did so tonight. It works great and my DaTafab CF card reader works on the pass-through. I did an install from the backpack drive. Fairly fast and very quiet. Now I need to start selling off some of the extra stuff I accumulated to get to where I am. I have 4 JRs, though some have issues, the Quadram unit with a 720k drive in it, 4 power bricks, 2 extra parallel port sidecars, 2 power sidecars, and two 128k IBM sidecars. Oh, and an extra BASIC cartridge. How did this happen? LOL
Enhanced PCjr with a jr-IDE (1GB DOM) and a parallel port side car with a compact flash reader and backpack 1.44mb floppy attached. Tandy video mod.
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