DECUS 12 BIT SPECIAL INTEREST GROUP NEWSLETTER Number 40 Summer-Fall-Winter 1980

This DECUS Newsletter (Number 40, Summer-Fall-Winter 1980) addresses a significant delay in its publication, attributing it to production issues and a lack of submitted contributions, while also announcing that DECUS SIG newsletter fees have been postponed for another year.

Key updates from the Fall DECUS Symposium include the absence of PDP-8 software exchange, new "aggressive" pricing for DECstation 78 products and software (OS/78, COS, WPS), the formation of a dedicated OS/8-OS/78 development and maintenance group, and rumors of a new 12-bit product from DEC.

A major technical section details challenges and solutions for interfacing the TU58 tape cartridge system with 12-bit machines, particularly concerning the necessary "BREAK" signal. This includes a discussion of a "breakless" host workaround, an OS/8 handler for the TU58 (developed by Jim Van Zee), and an innovative concept of using a VAX as a TU58 emulator for low-cost PDP-8 systems. The performance implications of TU58's interleaved blocks are analyzed, highlighting trade-offs between random and sequential access. Additional hardware modifications and a machine-independent TU58 bootstrap are also discussed.

Other software developments include Jim Van Zee's RX02 floppy disk handler supporting both drives and a U/W-FOCAL overlay dramatically improving symbol storage efficiency and variable limits. New DECUS Library submissions feature an OS/8 VAX Handler for file transfer and a Pascal-S compiler/interpreter for PDP-8. WPS-8 to OS/8 file conversion software is also highlighted.

The newsletter includes various user-submitted "Help" requests and community news: seeking assistance for Tennicomp MiniDec repair, reporting an OS/8 V3D BATCH bug, and a request for help in acquiring 1970 DEC DIBOL. A detailed analysis and potential solutions are provided for a persistent terminal switching bug affecting FORTRAN Run Time Systems. Other contributions include a new Sykes 7250 floppy disk duplicator program, identification of authors for DROP and RECOVR utilities, and a modified BLOAD for OS/8 BASIC to handle larger programs.

Finally, a performance report indicates that the DMM 8-30 programmable memory management unit significantly improves PDP-8 performance under RTSS, especially with multiple compute-bound OS/8s, allowing for reduced machine runtime.