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Bootstrapping a Compaq Portable

DefineDecision

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Sep 10, 2017
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I've recently found a Compaq Portable with 640 KB RAM, and no expansions installed other than the default CGA and LPT. However, the original owner wouldn't let me have any of the floppies, so i'm unfortunately stuck there. As all my old x86 stuff is from the 90s, I have no 5.25" drives or media, and have no ROM BASIC to fall back upon.

So, now I'm considering my options here, preferably picking the cheapest and quickest option.

* Get a 5.25" drive and disks to hook up to newer (but not modern) PC for bootstrap - I'll probably need to do this regardless - from there I can work on stuff like LapLink. Unfortunately, eBay prices for drives, cables, and disks are silly.

* Get a bridge system with 5.25 drives as well as newer interfaces. More money and more space.

* Get an XTIDE and bootstrap from a CF card - I have a 32 MB CF card already, so I wont need to bump up to DOS 4 or whatever. My two options are get a preassembled XTIDE (and not an Optima, considering what I heard about it) card, or the kit and soldering equipment and learning to solder. (Which I /should/ have done anyways.) It is quite pricey though.
 
I have an XT-IDE in mine, works well though I did have to get it all set up with my 386. If you get the connector, you can crimp a 3.5" drive connector and power adapter wire (ebay/amazon) and it will have a moderately good success rate reading 720kb 3.5" disks.

--Phil
 
I have a "half broken" 5.25 1.2mb drive that can handle 360k disks. I could let it go for $10 + shipping.

I say half broken because while the drive works perfectly, the drive close latch cam is busted, and it needs to be manually assisted to lock from the top of the drive.

I could toss in a 360k disk that's known good.

I don't have any spare cables, though I do have a 5.25" Parallel Backback enclosure that I would be willing to part with for another $20, and would work best for this drive to be left "in the open" to manually open/close by the cracked cam.
 
Will that Compaq recognize a 1.2M drive?
No. The Compaq Portable is low-density only. It will only work with 360k 5.25" drives or 720k 3.5" (or 1.44mb drives working as 720k only).

And it is a bad idea to write to 360k disks, that need to be read in a 360k drive, with a 1.2mb drive. Too much headache. To reliably inter-operate with a low-density 5.25" drive, get a 360k drive. With enough patients, 360k drives come up on eBay for $20-$30.

If the OP might post their location, perhaps someone local could provide a bootable disks with file transfer tools.
 
And it is a bad idea to write to 360k disks, that need to be read in a 360k drive, with a 1.2mb drive. Too much headache.

I haven't run across any problems (yet), and have formatted and copied files to 360k disks from my 1.2m Teac drive. What kind of problems should I be looking for?
 
I haven't run across any problems (yet), and have formatted and copied files to 360k disks from my 1.2m Teac drive. What kind of problems should I be looking for?
That's because you're reading them on the 1.2M Teac drive. That shouldn't be a problem in itself. The problem becomes more apparent when you try to read those disks on 360K drives. Some will fail while others won't. Bottom line is 360K disks formatted /written on 1.2M drives cannot be reliably read on 360K drives.
 
Can the disk drive from the Compaq be temporarily removed and installed in a network connected machine for the sake of writing a boot disk with a laplink or similar solution program?
 
That's because you're reading them on the 1.2M Teac drive. That shouldn't be a problem in itself. The problem becomes more apparent when you try to read those disks on 360K drives. Some will fail while others won't. Bottom line is 360K disks formatted /written on 1.2M drives cannot be reliably read on 360K drives.

Good to know. I guess I've just been lucky. I have been able to read them in my 360k drives (so far). I guess I should relocate one of my 360k drives to my tweener.
 
Good to know. I guess I've just been lucky. I have been able to read them in my 360k drives (so far). I guess I should relocate one of my 360k drives to my tweener.
Indeed you have then. Your mileage can vary quite a bit depending on the specific drives and disks used. Later model higher quality 360k drives will have fewer problems, and higher quality DSDD media seems to help. But plop those disks in a random unknown 360k drive somewhere and you will likely get piles of read errors.

Recently I have tried using that method, with disk formatted in a 360k, a number of times to save some time getting files from my main machine (with 1.2mb drive) to several of my other machines (with 360k drives). I have regretted it every single time. Some disks/drives will work fine, but others won't read at all. Finally I give up and take it to my 286 that has both 1.4mb 3.5" and 360k to write it properly, and THEN it works.

Some may point out that degaussing the disk before formatting and writing should result in a readable disks, but that is only practical for disks written all at once, such as with a kryoflux or ImageDisk, that will remain write-protected. Once you delete and write new files a few times, you may run in to the same readability problems. And then there is the problem of making sure the disks are really completely and properly degaussed, or having a degausser in the first place.

I have no idea how people put up with this when IBM first came out with the AT.
 
I had absolutely no trouble using high destiny disks in a high destiny drive to bootstrap my Kaypro II. I did have to use a bulk demagnetiser before formatting in the high destiny drive. Once read in the Kaypro, I used it to copy the disks to high destiny media in low destiny format. All is well.
 
I had absolutely no trouble using high destiny disks in a high destiny drive to bootstrap my Kaypro II. I did have to use a bulk demagnetiser before formatting in the high destiny drive. Once read in the Kaypro, I used it to copy the disks to high destiny media in low destiny format. All is well.
Two threads now referring to these disks that can control our future.. ? Stone, where are you ?
 
OK, thanks for the suggestions. I have plenty of spare 3.5" drives and media; I'll just try to format them down to 720k and install the drives whenever the mood hits me.

As for locations wrt media/etc offers: I'm in New Brunswick. (the province in Canada)
 
I had the best luck with 3.5" Sony drives. The high/low density switch appears just to change the flux density, regardless of you are writing a 1.44M disk as 720k. That makes for less "General error reading drive A:, abort, retry, fail?" moments.

Some drives work, some don't. Be prepared to spend an afternoon trying drives out. The Sony ones often have a drive number selection switch that means you can force it to being unit 0, have the twist in the cable and have the 5.25" drive as 1 so it'll boot properly off the 3.5" drive.
Oh and also, be prepared to get a bit creative when mounting the thing, the screw holes don't line up with modern carriers. What I did was got a half height 5.25” drive and a 3.5" drive in a carrier and mounted them side by side in the right bay. That then meant the left bay got a bunch of space for things like a hard disk. It also makes the machine a lot lighter, the full height floppy drives are heavy old things.

Phil
 
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