Ersatz-11

Ersatz-11 emulates an entire PDP-11 system in software while running on low-cost PC hardware. It outperforms all of the hardware PDP-11 replacements on the market, outstripping them by a particularly wide margin in disk-intensive applications. Hardware PDP-11 replacements that use a Q-bus, Unibus, or ISA bus for I/O can't come close to Ersatz-11's disk performance because they are limited to the speed of the I/O bus for all disk transfers, regardless of actual disk (or disk cache) speed. Ersatz-11 avoids this bottleneck since it uses the PC's main memory and takes advantage of the tight disk-to-memory coupling in modern PCs.

Ersatz-11 is by far the least expensive PDP-11 replacement product on the market. It quickly pays for itself in reduced maintenance, power, and climate control costs. Since its CPU is powered by the PC's processor and not a special-purpose processor card, there's no expensive custom hardware to maintain, and future upgrades to the PC's processor will make its PDP-11 emulation even faster.

Ersatz-11 available as free demo version (the One of each disk/tape controller type, 256 MB maximum total size of all disks), may be used for 30-day commercial evaluation, or unlimited personal/hobby use. The full version handles unlimited disk size, Massbus removable pack disks, PC multi-serial boards and Q/Unibus bus bridges.