National Semiconductor Corp, long a supplier of add-on memory for minicomputers, has entered the personal computer add-on market with a 16Mb memory expansion module for the Apple Macintosh II. NatSemi claims the NS8/16 provides the largest memory capacity and highest speed of any add-on memory for the Mac II and that it is the only one that supports both MAC-DOS and Unix. NatSemi’s RAMdisk software, packaged with the NS8/16, is claimed to eliminate the delays that commonly occur when users operating on hard or floppy disks switch from one application to another, enabling the user to address the memory board as if it were a disk. It uses 100nS 1Mbit dynamic memory chips and consists of 8Mb mother and 8Mb daughter boards; it can be configured with 4Mb, 8Mb, 12Mb or 16Mb at $400 a megabyte, occupying a single NuBus card slot. It provides 32-bit native mode addressing for the 68020 processor, and 24-bit address mode is also supported. NatSemi is promising other add-ons for the Macintosh line for later this year.