A Use of Fast and Slow Memories in List-Processing Languages A scheme is described which permitting a substantial increase in memory space utilized to store list-structured data. It consists in reducing to one level a nonhomogeneous store composed of fast (core) and slow (disk or drum) memories. The space available in slow memory is divided into pages each containing a given number of machine words. The reduction to a one-level memory is performed by a program which leaves the most often called pages in the fast memory. When a new page from slow store is requested, the page in core having the longest period of inactivity is transferred back to the slow store. The complete scheme has been implemented in connection with a LISP embedding into ALGOL, using an IBM 7044 with 32k of core memory and disks. Gains in memory space were about 100-fold. As often happens in programming applications the price of the additional space is computer time. Although the disks have an access time 10^4 times slower than core, tests indicate that the actual slow down varied from 3 to 10, depending on the number of pages available in the fast store. CACM February, 1967 Cohen, J. CA670202 JB February 28, 1978 4:06 PM 1626 5 1641 1641 5 1641 1641 5 1641 1641 5 1641 1708 5 1641 1781 5 1641 1860 5 1641 2299 5 1641 123 6 1641 196 6 1641 919 6 1641 990 6 1641 1007 6 1641 1046 6 1641 1131 6 1641 1139 6 1641 1140 6 1641 1149 6 1641 1198 6 1641 1215 6 1641 1223 6 1641 1265 6 1641 1303 6 1641 1323 6 1641 1358 6 1641 1366 6 1641 1366 6 1641 1389 6 1641 1421 6 1641 1421 6 1641 1460 6 1641 1462 6 1641 1463 6 1641 1467 6 1641 1468 6 1641 1477 6 1641 1491 6 1641 1496 6 1641 1496 6 1641 1502 6 1641 1531 6 1641 1535 6 1641 1565 6 1641 1601 6 1641 1602 6 1641 1613 6 1641 1614 6 1641 1626 6 1641 1626 6 1641 1626 6 1641 1641 6 1641 1641 6 1641 1641 6 1641 1641 6 1641 1641 6 1641 1785 6 1641 1786 6 1641 1787 6 1641 1788 6 1641 205 6 1641 224 6 1641 249 6 1641 288 6 1641 316 6 1641 378 6 1641 381 6 1641 398 6 1641 11 6 1641 404 6 1641 410 6 1641 463 6 1641 464 6 1641 483 6 1641 3184 6 1641 3184 6 1641 3188 6 1641 584 6 1641 600 6 1641 680 6 1641 691 6 1641 763 6 1641 799 6 1641