P
Phil Weldon
'sqrfolkdnc' worte, in part:
| Of course the LGP-30 had main memory AND the accumulator on DRUM, and
| addresses were NOT sequentially assigned.
_____
While I never worked with an LGP-30, though I helped get replacement systems
for it up and running. In 1965-66 Pittsburgh Plate Glass Company replaced
the LGP-30 in each of their 5 paint plants with Univac 1050 systems (24 to
32 K 6-bit core memory.) I remember discussions of placing data and
instructions to avoid rotational delay. For the 1050 replacements we had
severe memory limitations even with the much larger size; we used very
complex instructions (that took a very long time to execute) to compress the
code. The main I/O was 800 bit-per-inch tape; even sequential access was
slow.
Phil Weldon
| Of course the LGP-30 had main memory AND the accumulator on DRUM, and
| addresses were NOT sequentially assigned. A good programmer located
| his working storage so that it could be most often fetched in the same
| revolution as the instruction, then fetch the next instruction wihout
| wasting a whole revolution of the drum. There was a chart showing what
| memory locations could be accessed from an instruction at any location,
| without losing a revolution. It had 4096 words of memory, IIRC.
|
| Don't modern tape drives have multiple tracks, going to the end and
| back multiple times, so if you want to get to something 95% through the
| complete linear image, you only have to scan down one track part way to
| get it, not through 95% of the data?
|
| Of course the LGP-30 had main memory AND the accumulator on DRUM, and
| addresses were NOT sequentially assigned.
_____
While I never worked with an LGP-30, though I helped get replacement systems
for it up and running. In 1965-66 Pittsburgh Plate Glass Company replaced
the LGP-30 in each of their 5 paint plants with Univac 1050 systems (24 to
32 K 6-bit core memory.) I remember discussions of placing data and
instructions to avoid rotational delay. For the 1050 replacements we had
severe memory limitations even with the much larger size; we used very
complex instructions (that took a very long time to execute) to compress the
code. The main I/O was 800 bit-per-inch tape; even sequential access was
slow.
Phil Weldon
| Of course the LGP-30 had main memory AND the accumulator on DRUM, and
| addresses were NOT sequentially assigned. A good programmer located
| his working storage so that it could be most often fetched in the same
| revolution as the instruction, then fetch the next instruction wihout
| wasting a whole revolution of the drum. There was a chart showing what
| memory locations could be accessed from an instruction at any location,
| without losing a revolution. It had 4096 words of memory, IIRC.
|
| Don't modern tape drives have multiple tracks, going to the end and
| back multiple times, so if you want to get to something 95% through the
| complete linear image, you only have to scan down one track part way to
| get it, not through 95% of the data?
|
