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PDP-8/E Simulator 2.5.1

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Bernhard Baehr

Mar 6, 2023, 12:42:21 PM3/6/23
Hi all, there is a small optimization update available for the Macintosh PDP-8/E Simulator:

- The Memory Content and the VC8-E plug-ins now use CALayer based updates, significantly reducing the CPU load of the simulator.
- The RK05 drives are now able to mount SIMH DECpack images (with each 12-bit word stored in two bytes) directly; the images no longer need to be converted with the s2p and p2s tools.
- The Music Player plug-in no longer causes occasional skips of the music and avoids a deadlock in the AVAudioEngine when the simulator plays music while running at full speed.
- The OS/8 System Disk now contains the Popcorn piece arranged by Kyle Owen (RKB0:POPCRN.MU), see (Kyle, thanks again for this great fun).
- The indicator panel and drive select lights of the TC08 are now more consistent when restarting, resetting or clearing the simulator or the PDP-8/E or when the user manually changes Status Register A.
- Additionaly other minor bug fixes and adjustments esp. for macOS 13 “Ventura”.

As always, you can download the new version from


Apr 13, 2023, 4:49:21 AM4/13/23

Thanks Bernhard,
Seems to be more than just a small optimization update. Looks to me like it also includes a second ASR-33 TTY: as well as PC08 PTR:/PTP:

I've been running this update for a couple of weeks and I've been happy with it.

-- steve

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