LinuxSA Mailing list archives

  From: Stephen Donaldson <steve@cyberqual.com>
  To  : David Newall <davidn@rebel.net.au>
  Date: Thu, 29 Jun 2000 18:51:08 +0930

Re: More space required (for oldies only)

Sheesh, this brings back memories ;-)

My Sinclair ZX81 was way cool for the time. <chuckle> My cassette tape was really
fast <mwahahaha>
My Spectrum 48k was magic (ahh for the Rebel Star Raiders my firt two player game)

BBC was super, although expensive (BBC basic still rules) Then there was ELITE
still the best Space Game Bar none. My crusty old Amiga come out for this
occasionally...HONEST

Jings guys, only oldies need read this <sob sob for the days of assemby-language
instructions>

Intel wa forced out of the Memory market the Japanese and were forced into
Micro-processors led by the famous, well in the computer fraternity ne'ways
Federico Faggin who never gave up demanding that resources were committed to the
Micro-processor. (The NMOS design based on negative charges and would run 2x the
current speed for 0, yes ZERO, nil naught design changes. "8008"
:-)

Not long after then a company called Zilog would have killed Intel but Intel used
the courts to hold them up for a year and a year at that time was an eternity. And
AMD would not be here today if not for Robert McNamara (JFK's Secretary of
Defence) who insisted that there must be two sources of  suppliers to the US
Government and INTEL provided support for AMD's survival inits early days.

Steve consumes another stiff drink and hobbles to bed and gets a few more blankets
for his old bones :-)

David Newall wrote:

> > So that my comments aren't extreme, the design of the PC at the time
> > was (in my opinion) excellent. Yes, it had flaws, but as a desktop
> > machine it was overall better than anything else out there.  Perhaps like
> > you, I had various flavours of MC6802/9/Z80 style desktops at that time, all
> > were good, but the pc had less overall flaws.
>
> Hmmm, interesting perspective.  It used a 16 bit CPU with an 8 bit data bus
> (8088), and came standard with 128KB of RAM.  Options included upgrades to
> 512MB of RAM but no further.  It included the ubiquituous cassette
> interface, and a choice of one or two floppy disk drives.  Video display
> was provided by a choice of MDA (monochrome display adaptor) or CGA (colour
> graphics adaptor)  System clock ran at ... goodness me, I'm scratching to
> recall whether it was 5MHz or 8MHz.  Maximum address space was 1MB, of
> which the top 384MB is reserved for BIOS and hardware, leaving 640KB
> addressable for programs and data.
>
> The PC included an 8 level programmable interrupt controller, of which I
> think five interrupts were unassigned.  This was a good thing and a bad
> thing.  Without doubt interrupt processing is simplified if you know for a
> fact that only one device uses any interrupt level.  On the other hand, we
> continue with the legacy of IRQ conflicts to this day.
>
> It's competitors at the time were the Apple ][, which used a RISCish 8 bit
> CPU (6502), and came (at the time) standard with 48MB RAM.  The Apple ][
> was venerable even then, and also included a cassette interface.  It came
> standard with colour graphics, had a choice of between zero and twelve
> floppy disks, and between zero and six hard disk drives.  The Apple ][
> system clock ran at 1MHz.  The Apple ][ had two interrupts: One maskable
> (ie the hardware could choose to ignore it) and one non-maskable (it could
> not be ignored.)  Thus the Apple ][ never did have a problem with interrupt
> conflicts.  Maximum address space was 64KB, of which 12KB was preloaded
> with BIOS, 4KB was reserved for general hardware, and various amounts,
> depending on video mode, was reserved for the screen.  The fractured
> address space was one of the ]['s biggest weaknesses.
>
> Another competitor was the Apple ///, which initally came standard with
> 128MB RAM, and later 256MB.  The Apple /// could be upgraded to 512MB.  It
> also had colour graphics as standard.  The Apple /// was, in fact, a
> typical Apple hack, which is to say it abused the intended design in quite
> clever ways.  The Apple /// system clock ran at 2MHz, and, like the IBM PC,
> included a standard real time clock.  The Apple /// was an upgraded Apple
> ][.  It had a maximum address space of 64MB of RAM and used sophisticated
> bank-switching to take advantage of the addition RAM that the machine could
> accomodate.
>
> The Apple //e was a contempory of the Apple ///.  It came standard with
> 128KB of RAM, and was rather like a cut-down Apple ///.
>
> Compared with the Apple ][, //e and ///, the IBM PC was a superior machine.
> It could directly address much more memroy, although the 8086's segmented
> addressing mode made this almost as hard to use as the Apple ///'s
> bank-switched memory.  The 8 level interrupt controller has not proven to
> be a benefit, in that it's one of the major causes of hardware
> configuration errors.  Apple's machines de jure were no-brainers to
> configure: You pop a hardware card into an available slot and it just
> worked.  Intel's IO bus has proven to be another nice idea that failed to
> live up to it's promise: Having to ensure hardware IO addresses are
> correctly configured is the second major source of configuration errors on
> PC's, and this also continues.  (Thankfully we're getting around this by
> making the hardware configure itself; but this is a work-around to an
> unneccesary design deficiency.)
>
> Around the same time as the release of the IBM PC, Apple released the Lisa.
> This used a 68000, and I frankly forget how much memory it included as
> standard.  I'm inclined to think it came with 1MB and went up from there.
> The Lisa had no video options: You got monochrome graphics.  The Lisa came
> with a choice of one or two typically Applie wierdoed floppy drives, and
> with one hard disk drive.  (I don't know if you could have had more.) There
> is no question that the Lisa had an operating system which was ten years
> (or more) in advance of the IBM PC.  I should say that Microsoft only
> caught up with the Lisa five years ago -- and the Lisa was an early 80's
> machine.
>
> Soon after the Lisa, and certainly contemporaneous with the IBM AT, came
> the Macintosh.  This was rather a cutdown Lisa.  It initally came with
> 128KB of RAM, and a choice of one or two floppy drives.  Apple released
> upgraded versions in quick succession, mostly to expand the RAM and provide
> hard disk capabilities.  As with Lisa, the Macintosh had a vastly superior
> operating system than the Lisa.  (Sadly the Mac is still behind Lisa in
> terms of OS design.  MacOS X will finally rectify that.)
>
> I have to say that the IBM PC was faster than the Apple ][, //e and ///,
> and could make sane use of more memory, however it was not excellent.  Many
> of the design choices turned out to have two edges: The choice of the 8086
> was perhaps the worst, with its separate IO bus and segmented architecture.
> The use of the PIC in the PC, and later a second cascaded PIC, has been of
> dubious value, and it's a fact that even today trying to correctly
> configure all of the installed hardware is a major source of effort and
> failures.
>
> The PC was by no means an order of magnitude better than Apple's low-end
> machines, and compared to Apple's newer machine, Lisa, I think the
> convincing argument is that PC was inferior.
>
> In terms of available software, the Apple ][ held it's own for a long time.
> Apple's DOS was not as good as PC-DOS, but it wasn't much worse.  Apple's
> SOS (for the Apple ///) and ProDOS (for the Apple ][ and //e) was much
> better than PC-DOS.
>
> I hope you will understand that I have not included third party add-ons to
> any of the machines of the time.  They do change the story, but perhaps not
> the result.
>
> I'm unconvinced that "the design of the PC at the time was excellent."
>
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