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More than two hard disks in DOS

os2museum.com

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Re: More than two hard disks in DOS

#41

Post by kalleboo »

philipstorry wrote: post #2

Quite the nostalgia blast for me! I'm honestly not sure I had a machine with more than 2 fixed disks until well into the days of Windows 7 and SATA. The exception would be logical disks such as Stacker or similar compressed volumes - but I wasn't using them until later either. If I recall correctly before SATA we had IDE which only had two devices (primary & secondary) per controller, and usually only two controllers…

I had 3+ fixed disks somewhere around 1997, but that was on a Mac (so built-in SCSI), and the drives were all hand-me-downs that I got for free, that I could just plug and play to add a few more hundred megs of storage.

Re: More than two hard disks in DOS

#42

Post by burnt-resistor »

blueflow wrote: post #9

> ... was missed for years simply because no one had a PC with more than two hard disks. Thats a hardware limit: Early mainboards only had a single IDE / parallel ATA port. Each port has two pins for drive select, so you had a maximum of two addressable drives, the master and slave drive. With a secondary ATA port you got another set of master/slave, pushing the limit to 4 drives. That's where the "primary master" te…

ST, MFM, and RLL drives and controllers were the thing then. (The GRC SpinRite low-level format era.)

P-ATA IDE didn't arrive until the late 80's.

Re: More than two hard disks in DOS

#43

Post by roryirvine »

accrual wrote: post #13
st_goliath wrote: post #11

Earlier quoted context omitted.

> Early mainboards... ... like in the PC AT, PC XT[1] or the Compaq DeskPro 386[2] that the article discusses didn't have those ports at all . Those were instead on ISA expansion cards, just like the floppy controller that would often share a card with the UART controller for the serial interface. [1] https://theretroweb.com/motherboards/s/ibm-xt-type-5160-64-2... , [2] https://theretroweb.com/motherboards/s/compaq-d…

Yes, the earliest mainboards I know of with on-board I/O including ATA is around Socket 5, the first mainstream Pentium boards. Some slightly older Socket 4 boards (circa 1994) have on-board I/O, but they weren't as common. My 486 and earlier systems have all I/O provided by ISA cards, other than the 5-pin DIN keyboard port which was standard since the original PC.

I remember my dad's Dell 486P/33 from 1991 had integrated IDE, but that was a fairly high-end machine at the time (the forerunner of their "Precision" workstation range).

Details here: https://theretroweb.com/motherboards/s/dell-system-486p

But, yes, most bog standard machines would've had a separate "SuperIO" card containing serial, parallel, and IDE interfaces until the mid 90s.

Re: More than two hard disks in DOS

#44

Post by accrual »

roryirvine wrote: post #43
accrual wrote: post #13

Earlier quoted context omitted.

Yes, the earliest mainboards I know of with on-board I/O including ATA is around Socket 5, the first mainstream Pentium boards. Some slightly older Socket 4 boards (circa 1994) have on-board I/O, but they weren't as common. My 486 and earlier systems have all I/O provided by ISA cards, other than the 5-pin DIN keyboard port which was standard since the original PC.

I remember my dad's Dell 486P/33 from 1991 had integrated IDE, but that was a fairly high-end machine at the time (the forerunner of their "Precision" workstation range). Details here: https://theretroweb.com/motherboards/s/dell-system-486p But, yes, most bog standard machines would've had a separate "SuperIO" card containing serial, parallel, and IDE interfaces until the mid 90s.

Wow! Very impressive board, I had no idea. It's kinda cool how we can directly see some of the chips that would be on the SuperIO card but directly on the mainboard. Thanks for sharing.

Re: More than two hard disks in DOS

#45

Post by nubinetwork »

bombcar wrote: post #15
alnwlsn wrote: post #14

Earlier quoted context omitted.

Similarly, it always bothered me a little that the floppy disk interface was designed for 4 drives, but the PC standard came up with the clever hack of putting the twist in the cable, so they didn't need to adjust drive jumpers, which also reduced it to 2 drives. On the TRS-80, they just ordered all the drives jumped with all 4 positions, then pulled out the other 3 unused pins in the connector on the cable.

The twist as a "cute" solution that made it mostly plug-and-play; the biggest upgrade on some of those older machines was adding a second floppy, and the twist made it simple and foolproof.

Unless you had an IBM ps/2... those non standard floppy drives were horrid to deal with.

Re: More than two hard disks in DOS

#46

Post by cestith »

shdon wrote: post #40
cestith wrote: post #35

Earlier quoted context omitted.

There were also a number of sound cards that had two or three ports because a lot of early CD-ROM drives weren’t IDE. You’d have a Sony, a Panasonic, and something else on your card in the early days. IDE on a sound card was an actual improvement.

The third common CD-ROM interface that wasn't IDE was Mitsumi.

Thank you. That’s absolutely right and I’m not sure why I blanked on it at the time of writing.

Re: More than two hard disks in DOS

#47

Post by inetknght »

bombcar wrote: post #36
inetknght wrote: post #28

Earlier quoted context omitted.

> that's the equivalent of a modern laptop (which comes with checks Apple 16GB of RAM) going up to 640GB of RAM 640GB of RAM doesn't sound unreasonable to me.

Found the Chrome user.

Nope, no installs of Chrome here.

I use a lot of virtual machines and games though.

Re: More than two hard disks in DOS

#48

Post by tracker1 »

hypercube33 wrote: post #39
tracker1 wrote: post #24

Earlier quoted context omitted.

You're jumping ahead a bit... early motherboards didn't have drive adapters at all, let alone IDE or PATA. And it wasn't really limited to two by the board and expansion slots nearly as much as the physical form factor and cost. "Full-height" 5.25" drives are double the height of what you think of for say a CD drive bay or later floppy drive bays. There were two in the XT/AT cases that were common. Hard drives went f…

Wow it's been a minute since someone talked about the IBM "deathstar" drives. I remember building a PC and dumping my last money into a hard drive - ended up with a maxtor but envied the benchmarks of those IBMs. They later started failing in droves.

Yeah... it was crazy fast for the time, but when you lose, you lose. Not nearly as bad as the 3TB Seagate enterprise drives I had in an 8 drive array... 6 of the 8 failed days after the relatively short warranty. I've had exceedingly good luck with all the ssd/nvme drives I've used though.

Re: More than two hard disks in DOS

#49

Post by hakfoo »

accrual wrote: post #13
st_goliath wrote: post #11

Earlier quoted context omitted.

> Early mainboards... ... like in the PC AT, PC XT[1] or the Compaq DeskPro 386[2] that the article discusses didn't have those ports at all . Those were instead on ISA expansion cards, just like the floppy controller that would often share a card with the UART controller for the serial interface. [1] https://theretroweb.com/motherboards/s/ibm-xt-type-5160-64-2... , [2] https://theretroweb.com/motherboards/s/compaq-d…

Yes, the earliest mainboards I know of with on-board I/O including ATA is around Socket 5, the first mainstream Pentium boards. Some slightly older Socket 4 boards (circa 1994) have on-board I/O, but they weren't as common. My 486 and earlier systems have all I/O provided by ISA cards, other than the 5-pin DIN keyboard port which was standard since the original PC.

White box systems didn't really acquire onboard I/O til the late 486/early 586 era, but it was pretty common on name-brand systems to integrate IDE/floppy/serial/parallel and usually video.

Re: More than two hard disks in DOS

#50

Post by hakfoo »

rwmj wrote: post #23
bombcar wrote: post #17

Earlier quoted context omitted.

People laugh about that, but when you look at when the whole thing was designed and came out, and how much it would have cost to have a "pimped out" system that pushed the limits (if even possible!) it becomes much more reasonable. Nobody expected this silly machine to be relevant and affecting computing 44 years later! It came with 16KB of RAM! 640KB would have been 40 times as much - that's the equivalent of a mode…

What you say is true, but I'd also like to ask (people in general) if you have to design a memory map for MS-DOS that doesn't have the 640K limit, what would you do? Your constraints are: - The total address space is 1MB, and that's a CPU architectural limit (which is only "broken" many years later, and in a rather unsatisfying way). - You need somewhere to map the RAM, and because of CP/M quasi-compatibility, that n…

The address space didn't have to start at 0. In fact, address 0 contains interrupt vectors. I suspect most of the CP/M compatibility was about starting at specific addresses within a given segment (isn't that why .COM executables are placed at 0x100?)

I blame Intel by having the boot address at FFFF0. That guarantees you need ROM at the top of memory rather than loading boot code and sticking frame buffers in low memory, and starting user RAM at like 0x20000.

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