On 01/03/2026 20:55, Van Snyder via cctalk wrote:
On Sun, 2026-03-01 at 13:12 -0600, Steve Lewis via cctalk wrote:
I still think it's a good bet that MULTICS at some point existed in
the
form of punch cards. (as also SCOPE, AOSP, and Atlas Supervisor).
IBSYS on 7090/94. PR-155 on IBM 1410/7010
Pretty sure that there never was a copy of IBSYS source on cards, well
except for the very first version. Reading source cards is slow, you
want it on tape.
IBSYS included a Symbolic Update Program which you could use to "edit"
source tapes in a similar way to which you use DIFF and PATCHÂ on a
modern system.
https://www.bitsavers.org/pdf/ibm/7090/C28-6386-1_symbUpdPgm_Jan65.pdf
"Update may be used to modify any tape written in BCD mode, provided
columns 73-80 of card images are available for serialisation"
&
"In addition, it can be used to maintain subsystems of the IBSYS
Operating System and the operating system itself"
.. so even from the very early days IBSYS source was stored on tape.
.. and as for "boot loader" I don't know how a 7090 worked but S/360
came with loadable tapes. What other folks call "booting" IBM refer to
as "Initial Program Load" (IPL).
On S/360 there are three dials that set the device address you are going
to load, and an IPL button that executes a special IO command that does
a read and starts executing what was read.
Dave
p.s. read the 7090 ops guide, there are two LOAD buttons one for card
and one for tape....
