MS-Dos

It should work on the 386 and might work on 486 standard motherboards.

I think version 5 was a fix just before they came out with MSDOS 6.0 to host Windows 3.1.

Been a lot of years since then.

DAB

Would it be a blast to catalog how many modern machines can run MS/PC-DOS? I wonder a contest of sorts.

LOL

Clem

The boxed DOS I have is on 5 1/4" floppy, luckily my 386 has a 5 1/4" drive.

360K or 1.2M ?

The disks spin at different rates 300RPM and 360RPM.

Just remember that 360K disks may not read or write well in a 1.2M drive.

Oh, I almost forgot the dual format 1.2M 5 1/4 drives.  If I recall, they didn't have trouble with reading, only with a write/read cycle.  The reason was the voltage level for the head was decreased so the "spot" of data would be smaller.

Goes to another potential issue, which might just be urban legend. Data degradation on old magnetic media.  Not sure the data image has held up over the decades since DOS 3.1.

Interesting idea.

I may have to fire up one of my legacy systems to see how well the floppys work.

DAB

Hi DAB!

I used to design floppy drive systems and my mentor used to service and align them properly.

It's amazing how many floppy disk drives weren't optimally aligned! (Hence the woes of unnecessary read errors).

Would anyone be interested is a series of fun articles about them?

It might come out in dribs and drabs due to my illness.

Compact

Hi Monte,

I think such a series would be a nice trip down memory lane for some of the members, including me.

So don't overtax yourself, but I look forward to your posts.  Get better soon.

DAB

Sounds like a great idea, I would love to learn more as well. This could be a start of a fun journey, teach younger members that speed isn't everything!

As a note, my 386 has a 14.4 modem, time for dial-up!

14.4kbps was an amazing feat especially over a phone line is was limited to a 3kHz bandwidth.

It was a great use of DSPs (Digital Signal Processors).

I used to worked for several modem manufacturers during my career.

300 baud just used FSK (Frequency Shift Keying), faster speeds used more elaborate schemes.

My first modem for my 8088 was a 1200 baud. It was top speed at the time.

I started with 110 and 300 baud connections.

We thought 9600 was a tremendous improvement.

DAB

I started with 110 and 300 baud connections.

We thought 9600 was a tremendous improvement.

DAB

The first modems I used were this speed and acoustically coupled to the telephone handpiece.

This made it easier to get Australian regulatory approvals rather than direct attachment.

To get Australian regulatory approvals for directly connected modems the designs needed to provide 4kV isolation and other protection measures to ensure that the phone line remained safe as not to increase the risk of electric shock to any linesmen working.

The reason for 4kV isolation rather than 1.5kV isolation as used in the USA is because in Australia we have very long telephone wires (mostly in remote areas) that could plausibly induce rather large voltages.

With FSK the speed crept up to 1200 half duplex on two wires and 1200 full duplex on 4 wires, 1200/75 on two wires. (to CCITT standards)

The speed increased to 2400 baud using PSK (Phase shift keying).