3.5 inch already peaked in 1985, thats when NEC first shipped 1.44MB inside PC-8801 mkII MR. IBM followed two years later switching PS/2 to HD floppies, Apple in 1988. 80 tracks ~50KB/s speed. In 1990 IBM bumped PS/2 to 2.88 ED. Different magnetic material, double the bitrate, ~100KB/s.
... But NEC beat IBM by already doing 'five blades' in 1988 selling PC-88 VA3 with 'Triple' or '2TD' format 3.5" floppy sporting 13MB unformatted 9MB formatted capacity. Same perpendicular head as ED, same magnetic medium, same bitrate, 3 times more tracks (240) while still using cheap stepper motor unlike ZIP head actuators, compatible with same standard ED floppy controller chips. Sadly no one in the west adopted it :(((
There was one more avenue for bumping capacity never really explored on PC - zone bit recording invented by Chuck Peddle in 1961 and supported by Floppy controllers in Macintoshes, Commodore (Chuck Peddle designed drives) and Victor 9000 (Chuck Peddle designed whole computer). Free 50% capacity bump. Victor 9000 pulled 1.2MB capacity out of Double Density 80 track 5 1/4 drive.
Combine 2TD wiht ZBR and we could have had cheap 13.5MB formatted capacity floppies since 1988.
That's kind of the point of my comment - software developers couldn't release on NEC without excluding IBM customers etc etc. They were stuck with 1.44MB because that was the only thing guaranteed to work. There was a human management problem around agreeing on a specification; drive manufacturers and software companies simply had conflicting incentives, so the market was a mess.
In retrospect I think the only reason Zip was able to become the undisputed market leader in high-capacity disks is that CD-ROM fully took over commercial software distribution.
I disassemble and read a lot of vintage bioses for fun. Recently I looked at something more ~recent, an Atom N270 945GSE Mini-ITX industrial board from 2010. Phoenix bios:
Yes, the far jump was never necessary on any processor, only a convention. You can stay in the same segment as in real mode and it will continue to work. But some kind of control transfer to flush the queue must be done shortly after the LMSW / MOV CR0, or things may break in ways that I'm not entirely clear on.
My test code looked like this:
mov ax,1 ;new MSW
mov bx,TestSel ;pointer to selector value into BX
mov dx,[bx] ;and load into DX
mov cl,31 ;shift count for delay
cli ;disable interrupts
lgdt [Gdtr]
lidt [Idtr]
jmp enter_pm ;flush queue now
align 2
enter_pm: ;go!
rol cl,cl ;delay while following instructions decode
lmsw ax ;set PE bit
mov es,[bx] ;should load selector 0x0010 into ES
mov ds,dx ;should set DS base to 0x00100 [NOPE]
str ax ;should trap because not allowed in real mode
ud2 ;trap anyway in case it didn't
On the 286, this always caused the processor to reset. Replacing one of the two segment load instructions with a same-length "mov ax,ax" didn't change that, but removing one of them did.
In that case the "str ax" acted as the control transfer that flushed the queue (it was still decoded in real mode, so it went to the "invalid opcode" entry point). No clue as to what exactly happens to cause the reset when three instructions are run from the queue, some timing issue related to when the PE bit actually changes vs. what the decoder is doing at this point?
Guess: Intel changed the spec. There's quite a few generations between a 286 and a P4, and new BIOS code doesn't need to run on discontinued CPU types. And new execution contexts like https://en.wikipedia.org/wiki/System_Management_Mode might benefit from minimizing the setup needed to run in protected mode.
In 2011 Poland 2600MHz LTE band was auctioned off with the condition winning bidderwould offer free 512Kbit mobile internet called 'Bezpłatny Dostęp do Internetu' aka BDI (translates free access to internet) for 3 years, amount of time it should take them to build full country coverage.
... except they failed to build the network deciding to concentrate on most profitable cities instead. National regulating body UKE (Office of Electronic Communications) didnt like that one bit and first expanded free period to 2016, and then in 2016 made extension indefinite until mandated 50% coverage is reached + 3 years. This happened in 2021 forcing them to provide it all the way to 2024.
TLDR 2011-2024 free government mandated mobile 512Kbit internet.
Funnily enough Aero2 - company in question decided it was a good business after all and is still offering "free unlimited" trier, in quotes because you have to renew it every 12 months paying ~$1.5 https://aero2.pl/zasady-dzialania/
"A McGraw-Hlll PIIIJIICGIIOI1/0360-5280" " and dBonk erformance nc ie and t load ng ter 1 even " doesnt appear so
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