Version 2.1:
- The PDP-8/E Simulator now is a 64-bit application fully supporting macOS 10.14 'Mojave' Dark Mode and still retaining compatibility to old Macs with Intel or PowerPC CPUs running Mac OS X 10.4 'Tiger' or newer
- Many adjustments for 64-bit mode, macOS 10.12 SDK and Xcode 8.2.1; esp. the memory inspector drawer is now a panel (NSDrawer is deprecated and has no black appearance in 'Mojave' Dark Mode) and all registers are now text fields (the formerly used NSForm and NSFormCell are deprecated and do not draw the register content reliably with 'Mojave')
- App Nap is now disabled when the PDP-8/E runs to avoid massive slowdown when the simulated machine works for a while without user interaction. More robust ASR 33 thread synchronization now avoids sporadic stops of the input when OS/8 BASIC reads source code from taper tape or via Copy & Paste
- When pasting multi-line text in the ASR 33, the line feeds are now handled correctly; before, the pasted text was handled as one long line
- ASR 33 toolbar removed, the controls are now at the top of the window. Position of the progress bar and the file label in the ASR 33 and PC8-E paper tape reader and punch exchanged
- The RK05 drives now avoid file I/O for unmounted disks; before, the MAINDEC-08-DHRKA-B-PB RK8-E Diskless Control Test was able to cause this in rare cases, resulting in an immediate crash of the simulator
- The RK05 drives are now correctly initialized and the devices implemented by plug-ins are correctly reset when no preference file for the simulator exists, i. e. at the very first launch of the app
- The EAE instructions SHL 37, ASR 37 and LSR 37 now correctly clear AC and MQ when executed on Intel CPUs in 32-bit mode and EAE mode A: these are 32-bit shifts were ignored by Intel CPUs in 32-bit mode (deteced with MAINDEC-8E-D0LB-PB KE8-E EAE Instruction Test Part 1)
- Improved performance of the Memory Content plugin
PDP-11 (Programmed Data Processor-11) is one of the most famous computers in computing history, one of a series manufactured by Digital Equipment Corporation ( DEC ) from the early 1960s through the mid-1990s. PDP-11, which was sold in 1970 for $10,800, was the only 16-bit computer ever made by the company.
Ersatz-11 is a software replacement for PDP-11 minicomputer systems. When running on typical PC hardware, it substantially outperforms any PDP-11 model ever produced by DEC, outpaces all known aftermarket clone CPUs, and is the fastest PC-to-PDP-11 software emulator available at any price. Yet it is the most inexpensive PDP-11. Developer of Ersatz-11, a software PDP-11 emulator for MS-DOS, Windows, Linux, OS/2, and bare-metal PCs giving emulation speed far faster than the PDP-11/93. The free demo version may be used for 30-day commercial evaluation, or unlimited personal/hobby use.
The PDP-11 had a number of other features that distinguished it from most of its contemporaries, including multiple (eight) register s; multiple addressing mode s; a hardware stack ; processor error trap s; and a separate communications path for memory and peripherals (called the UNIBUS ) that could move data independently of the processor. Many early developers and users of the UNIX operating system ran it on the PDP-11 after the original Multics system was no longer available.
Before the 1970s, computers were not thought to be something that the average person would buy or use. At about $1,000,000, they were prohibitively expensive. Furthermore, computers of the time were so large and complex that a computer center was required to house one and a sizable staff was required to look after it. To dissociate their product line from these public perceptions, DEC didn't refer to the PDP as a computer at all, but used its name, the Programmed Data Processor, as a generic term. DEC's first model, PDP-1 sold for $120,000 - about 40 times the price of a good computer today, but a bargain at the time.
DEC was acquired by Compaq Computers in 1998.