Mike's PCjr Page

I've been watching this auction for a little while, thinking about buying one:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0606702875

I can't find any system requirements listed for the DOS drivers, though. Any idea if it would work on the PCjr?

I used to have a parallel hard drive setup like the one described in that auction, but a different brand, and I was never able to get it to work on a straight IBM PC. The problem I had was that the driver was too large to fit on a 360K diskette, let alone the rest of the DOS files, and it seems that it was designed to provide a machine with an internal hard drive an external portable option. I highly doubt that this will work of the Jr, but feel free to try. If you get it to work, I will buy one too

I think it would work, but I'd like to have the device in my hands to try it. (And those prices are not unreasonable for an experiment, so I might just try it out.)

I've had very few problems with device drivers - as long as they require an 8088 and something like DOS 3.3 or DOS 5, there is a good chance it will work. I've had quite a few SCSI cards, Ethernet adapters, the Iomega Zip drive GUEST drivers (using a NEC V20), the backpack parallel port drive, etc. running on a PCjr.

The software to drive an IDE hard drive from the parallel port should be tiny - no more than 20 or 30KB resident in memory. The additional software to partition the drive and manage it might not have fit on a floppy, but the device driver itself should be no big deal.

Brutman wrote:
The software to drive an IDE hard drive from the parallel port should be tiny - no more than 20 or 30KB resident in memory. The additional software to partition the drive and manage it might not have fit on a floppy, but the device driver itself should be no big deal.

Wouldn't that render the drive useless if you cannot manage it?

Vorticon wrote:

Brutman wrote:
The software to drive an IDE hard drive from the parallel port should be tiny - no more than 20 or 30KB resident in memory. The additional software to partition the drive and manage it might not have fit on a floppy, but the device driver itself should be no big deal.

Wouldn't that render the drive useless if you cannot manage it?

Not a big deal to me, I can put the management software on a 720k floppy and access it from my second drive. That 2-drive mod for the PCjr floppy controller is extremely useful.

Of course, I can't try any of this until I have my PCjr's motherboard replaced, but it's fun to think about.

EDIT: Actually, the whole reason I want to try this is because I have a 20mb IDE hard drive from an old laptop that I'd be able to access from DOS 3.3 without a problem, providing the driver will load on DOS 3.3. Even if I have to use DOS 5, though, I'm thinking the free space calculation would go a lot faster.

EDIT 2: Even without a 720k floppy, I don't see what would stop you from partitioning the drive on another computer before attaching it to the Jr. I did that with my ZIP drive.

If you download the drivers from the link and look at how it works, it really only relies on two files for DOS; DRIVLOAD.COM which is a common way to load drivers into RAM after config.sys and EGIDE100.SYS -- which together barely break 60k, so the driver size thing shouldn't be an issue.

You load that sys file (45k) in your config.sys I don't think you'd have any problems.

Unfortunately, most parallel-port adapter drivers rely on REP INS to read from the drive, and that's only available on 80188 and higher, or NEC V20/V30. So if you have an NEC in your Jr, give it a shot. Otherwise, don't bother.

I attempted to disassemble GUEST.EXE and it's resulting driver overlay for parallel port operation to see if it would be easy to replace REP INS with (much slower) 808x equivalent code, but the system seems too complex for a weekend, and my free time is limited.

Now, an older version of GUEST, where everything was packed into a single .exe, that would be doable. However, I can't seem to find any versions of GUEST older than 5.x and 5.x uses the loadable overlay system. If anyone has a version of GUEST that is old enough to work perfect with only the GUEST.EXE program, let me know and I'll attack it. I'm at trixter_at_oldskool_org.

Yup, I have a V20.