2 Oct
2002
2 Oct
'02
3:45 p.m.
Well I'm not sure as to indexing, but I know that the entire memory on the
LGP-30 is the drum.. nothing else, well at least not programmable anyway..
and no, I/O devices aren't memory! heh
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2 Oct
2 Oct
5:24 p.m.
Will Jennings wrote:
Well I'm not sure as to indexing, but I know that
the entire memory on the
LGP-30 is the drum.. nothing else, well at least not programmable anyway..
and no, I/O devices aren't memory! heh
Jerome Fine replies:
When I first saw this line, I did not thing of a drum system as
having indirect addressing. However, if this qualifies, then
the IBM 650 system that must have been produced prior to
1960 (I used one in 1960) also had a drum to hold both
instructions and data. Each IBM 650 instruction was
10 decimal digits - the IBM 650 was NOT a binary
computer. The first 2 decimal digits were the op code.
the next 4 decimal digits were the address of the operand.
The last 4 decimal digits were the ADDRESS of the next
instruction on the drum. The assembler program to convert
the source language into machine language was called SOAP -
Symbolic Optimal Assembly Program.
Sincerely yours,
Jerome Fine
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3 Oct
3 Oct
6:23 a.m.
On Wednesday, October 2, 2002, Jerome H. Fine wrote:
When I first saw this line, I did not thing of a drum
system as having
indirect addressing. ... The last 4 decimal digits [of an instruction]
were the ADDRESS of the next instruction on the drum.
That's not indirect addressing. What I mean by 'indirect addressing' is
'accessing data at run-time-computed addresses'. You're talking about
accessing code at hardcoded addresses.
I was thinking of the first machine that supported indirect addressing in
its instruction set, but we should also count machines where you could
kludge indirect addressing by modifying the machine code before executing
it.
--
Jeffrey Sharp
7:31 a.m.
Jeffrey Sharp wrote:
I was thinking of the first machine that supported
indirect addressing in
its instruction set, but we should also count machines where you could
kludge indirect addressing by modifying the machine code before executing
it.
But surely ANY computer (other than Harvard architecture machines which
seaprate code from data) can modify their own program. In that case I do
not hesitatte to nominate the Manchester Baby machine, first operational
program in June 1948. It did not have any hardwired indirect addressing
but it could certainly modify its own program.
-- hbp
9:22 a.m.
Hi,
Hans B Pufal <hansp(a)aconit.org> said:
Jeffrey Sharp wrote:
Indeed, and that was the normal way of indexing arrays on EDSAC (1949).
(I'm just writing some simple test programs for the emulator, so
I know that's the only way to do it!).
--
Cheers,
Stan Barr stanb(a)dial.pipex.com
The future was never like this!
I was thinking of the first machine that
supported indirect addressing in
its instruction set, but we should also count machines where you could
kludge indirect addressing by modifying the machine code before executing
it.
But surely ANY computer (other than Harvard architecture machines which
seaprate code from data) can modify their own program. In that case I do
not hesitatte to nominate the Manchester Baby machine, first operational
program in June 1948. It did not have any hardwired indirect addressing
but it could certainly modify its own program.
7997
days inactive
7998
days old
4 comments
5 participants
participants (5)
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hansp＠aconit.org -
jhfinepw4z＠compsys.to -
jss＠subatomix.com -
stanb＠dial.pipex.com -
xds_sigma7＠hotmail.com