Booting an IBM MP 3000 S/390 System

Jay Jaeger cube1 at
Thu Aug 6 16:17:50 CDT 2015

I see - I would have guessed quite a few more instructions than that,
based on my PDP-11 experience (my 8/L has only paper tape).

The PDP-12, which I have more experience at, takes about the same amount
of effort/time, but just the one I/O instruction in the switch register
(but then you have to enter the start address, and start the machine).

On 8/6/2015 4:03 PM, Johnny Billquist wrote:
> 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
>       START
> 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.
>     Johnny
>> 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.

More information about the cctech mailing list