Booting an IBM MP 3000 S/390 System

Jay Jaeger cube1 at
Thu Aug 6 13:43:27 CDT 2015

Acch.  All this modern/complicated stuff.  Once you powered on an IBM
1410 (2 seconds), you could have it (141O O/S: 1410-PR-155) running in
as little as a minute, counting the tape drive mount:

Mount tape on unit 0 [30 seconds tops, as tape is probably already there]
Storage Scan to +1
Sense switches to a blank character
[The above two were normally left that way]
Mode switch to CE
Computer Reset
00000    [This clears storage]
Computer Reset
Move Mode Switch to Display
00000    [Display before altering]
Press margin release on console typewriter while it types out "bbbbb"
Computer Reset
Move Mode Switch to Alter
A(WM)L%B000012$(WM)N   [Read tape to end of core/record to loc 12]
Computer Reset
[Wait about 10 seconds for 1410-PR-155 to load]


On 8/6/2015 1:21 PM, Fred Cisin wrote:
>>> Wow. I'll never complain again that it takes too long to boot Windows...
> On Thu, 6 Aug 2015, geneb wrote:
>> One thing I don't understand - why can't the machine boot on its own? 
>> Why would IBM design a computer that required another computer just to
>> boot it?
> "Why CAN'T the operating system have full functionality during booting?"
> I had an interesting conversation almost 30 years ago with a published
> expert on operating systemes and C programming, when he was bothered by
> why IO.SYS/IBMBIO.COM and DOS.SYS/IBMDOS.COM had to be in specific
> places on the drive.
> "Booting" is of course short for "bootstrapping", which is a
> multi-hundred year old term for a obviously ridiculously impossible
> task: "pulling yourself up by your bootstraps".
> I had always thought that that derived from Baron Von Munchausen,
> but a little research turns up that the baron had lifted himself
> and his horse out of the swamp by his pigtail, not his bootstraps.
> It wasn't until early 1800s that "bootstrapping" became the iconic example.
> The reason that IPL is called "booting" is because it is such an
> obviously ridiculously impossible task.
> "You can't use the operating system to load the operating system."
> Obviously it is simplest if somebody (or machine) outside, loads
> the code into memory, and then triggers a GOTO.
> Which is cheaper, or more reliable, a "trained" operator, or a
> smaller external machine?
> The really clever way, though, was to toggle in, or have a little ROM,
> to load a TINY bit of stored code ("boot sector") into RAM, GOTO it,
> and it could contain enough code to load a bigger chunk, which could
> have plenty of code to load the rest.
> Why not just put the OS in ROM?
> That would require more ROM, would make bug-fixes more difficult,
> and would make it more difficult to modify the OS to add new
> features, such as security holes.

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