Booting an IBM MP 3000 S/390 System

Johnny Billquist bqt at
Thu Aug 6 16:03:08 CDT 2015

On 2015-08-06 23:00, Jay Jaeger wrote:
> I should think that a set of manually entered bootstrap instructions
> (i.e., not on a diode ROM board) would take considerably longer than 5s.  ;)

You might think so. But when you see the bootstrap for the RK05 on a 
PDP-8, you realize that it takes about 5s to toggle it in and run it.

It's only two 12-bit words that you need to write after all...

In short:
6743  DEP
5031  DEP

When you've done it a few times, you get fairly proficient at it, and 
it's not hard to remember... Even faster on a PDP-8/A which have a 
numeric keypad frontpanel.


> On 8/6/2015 1:43 PM, Johnny Billquist wrote:
>> PDP-8 with OS/8 on an RK05. From power up until booted and ready was
>> basically the time for the disk to spin up, which was about 10 seconds.
>> The actual booting of the system is about 0.3 seconds. Add 5 seconds if
>> you had to manually enter the bootstrap.
>>      Johnny
>> On 2015-08-06 20:43, Jay Jaeger wrote:
>>> 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
>>> Start
>>> 00000    [This clears storage]
>>> Computer Reset
>>> Move Mode Switch to Display
>>> Start
>>> 00000    [Display before altering]
>>> Press margin release on console typewriter while it types out "bbbbb"
>>> Computer Reset
>>> Move Mode Switch to Alter
>>> 00000
>>> A(WM)L%B000012$(WM)N   [Read tape to end of core/record to loc 12]
>>> Computer Reset
>>> Start
>>> [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.

Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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