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There has been a considerable amount of questions and interest about Dense Pack programming techniques and the use-of-Boolean logic. While browsing through antique ZX publications I came across an interesting article written in 1983 by Sharon Aker (where are you now Sharon?). Since Sharon’s article merges nicely with my feeble attempts to explain the use…article, orig pub: 10.27.20, updated: 07.05.26

Reference: “Speed Up Basic‘ in Plotter (4/87). The use of Boolean logic with BASIC has not been covered well in computer literature. (Ed. Boolean Logic, named after George Boole, who defined an algebra of logical operations, such as AND, OR, and NOT, on the two values true and false). The Timex Sinclair computers are very…article, orig pub: 09.13.22, updated: 07.05.26

The following circuit will allow you to use the memory area above the EXROM, which ocupies the 0 to 8K chunk in that memory bank, as RAM. Cut the traces from pin 22 of the Exrom (mreq) and install the circuit in Figure 1. The easiest place to put this modification is a little left…article, orig pub: 10.27.20, updated: 07.04.26

ESC Escape control code circuit If you have a full-sized printer you might appreciate this circuit which generates the series of characters for the ESC escape control code – CHR$27; – with one keystroke. The circuit can be implemented if you use 4066’s to interface the keyboard with the computer. Here’s how Figure 1 works.…article, orig pub: 10.27.20, updated: 07.04.26

By using a combination of PAPER; INK and UDG screens we can have an almost endless variety of colors. Most color printing we see in magazines, packages etc. are printed using only four colors; cyan, yellow, magenta and black: These are called process colors. The seemingly endless varieties are determined by a combination of screened…article, orig pub: 09.13.22, updated: 07.04.26

Over 200 pages of educational material, written to be used as a self-teaching course in beginning machine code. Many examples and tips.book, orig pub: 04.05.20, updated: 03.13.26

Subtitle: The only book you’ll ever need to become an expert at the Timex/Sinclair 1000 and 2000book, orig pub: 04.05.20, updated: 03.13.26

Practical programs to do real jobs in a variety of environments. Included is a bulk storage program, word processing, financial applications, banking uses, plus educational programs. Author pushes the ZX81 and casts aside the idea that it is too small for any real computing work.book, orig pub: 04.05.20, updated: 03.13.26

Subroutines for applied math and plotting routines, for both TS 1000 and TS 2068. Available with cassette.book, orig pub: 10.18.20, updated: 02.15.26

30 games ranging from fortune telling programs to simulation of the ecosystem.book, orig pub: 04.05.20, updated: 01.24.26

While the Timex Corporation is best known for its watches, it also produced a number of other products since its inception as a clock company in the mid-1800s. During World War II, the company produced fuse timers for defense products, continuing through the 1950s and the Korean war. After the Korean war ended, Timex expanded…company, orig pub: 06.19.19, updated: 04.30.26

A machine code screen utility that lets you highlight any rectangular display region with new attributes while saving the originals for instant restoration via two USR calls.computer_media, orig pub: 07.15.23, updated: 06.28.26

A satellite orbit propagator that applies J2/J3/J4 gravitational perturbation corrections analytically to predict spacecraft position and velocity over time.computer_media, orig pub: 06.27.26, updated: 06.27.26

Converts observed satellite orbital elements to the smoothed mean elements needed by BgORBIT, using an iterative J2/J3/J4 perturbation correction loop that converges to sub-metre accuracy.computer_media, orig pub: 06.27.26, updated: 06.27.26

A least-squares differential corrector that fits mean Keplerian orbital elements to a time series of observations using analytically computed J2 secular partial derivatives and Gauss elimination.computer_media, orig pub: 06.27.26, updated: 06.27.26

About This Paper NASA Technical Paper 2811, published in March 1988, describes a method for predicting the position of an Earth-orbiting satellite using a personal home computer — specifically, the Timex/Sinclair 2068, a machine that cost less than $200, fit on a desktop, and drew about one ampere of power. The author, R. Asa Gordon,…document, orig pub: 06.27.26, updated: 06.27.26

Commented disassembly of the HOME ROM.document, orig pub: 03.27.26, updated: 06.04.26

Commented disassembly of the EXROM.document, orig pub: 03.27.26, updated: 06.04.26

Definitions for the HOME and EXROM disassemblies.document, orig pub: 03.27.26, updated: 06.04.26

The ZX COMPILER is a program, written in basic and machine code that will change a program in ‘BASIC’ into machine code. This can be used to create programs or sub routines that can run up to twenty or thirty times faster than normal BASIC! Because the ZX81 only has a capacity of 16K ram…document, orig pub: 02.11.25, updated: 06.04.26

User Groups Vendorsevent, orig pub: 02.14.23, updated: 03.12.26

Vendorsevent, orig pub: 11.27.25, updated: 11.27.25

Fourth annual event. Held at the Hara Arena in Dayton, Ohio on August 28th and 29th. Tim Swenson hosted the first of several after-fest BBQs at his house in Dayton this year. Several of the attendees appear in the photos below.event, orig pub: 03.30.23, updated: 02.24.24

Organized by Tim Swenson, the West Coast Sinclair Show was held in Union City, CA, on 5 June 1999, one week after the East Coast Sinclair Show. Vendors The key visitor to the show was the renowned author Stan Kelly-Bootle, writer of many computer books, including the “Devil’s DP Dictionary”, and the holder of the…event, orig pub: 07.04.21, updated: 07.10.23

British publication dedicated to Sinclair computers, most specifically the ZX Spectrum.periodical, orig pub: 12.11.19, updated: 06.11.26

Quarterly published by Tom Woods. Started as Pro/file Updates for owners of ZX Pro/File database. In 1986, the newsletter was renamed to Computer Updates and expanded to include updates to all software published by Tom Woods.periodical, orig pub: 10.11.25, updated: 06.06.26

Quarterly published by Tom Woods. Provided updates and more to owners of ZX Pro/File databasesperiodical, orig pub: 06.05.22, updated: 06.06.26

Newsletter of the Greater Cleveland Sinclair Users Group.periodical, orig pub: 07.10.22, updated: 03.13.26

Newsletter of the Sinclair Milwaukee Users Group (SMUG).periodical, orig pub: 10.02.21, updated: 03.12.26

Includes: “crater” – 3-D mathematical plot of the moon’s surface (Time Designs July/Aug ’85) “altaz” – Converts astronomic coordinates to altitude/azimuth (Time Designs Nov/Dec ’85) “udg” – Ultra-easy designer graphics for redesign of user-defined graphics (Time Designs July/Aug ’86) “son” – “udg” version 2 allows multiple fonts and more (Time Designs Nov/Dec ’86) “windows” –…product, orig pub: 05.14.20, updated: 06.28.26

Additions to Pro/File 2068, including all the improvements from the manual except where they are no longer appropriate (the machine code sort makes the block sort outdated), or improved by Robert Fischer’s routines in Extensions.product, orig pub: 11.07.25, updated: 06.28.26

Drawing package. Works in 256×192 or 512×192. Draw, line, box, square, circle, invert, block invert, block erase, merge screens and more.product, orig pub: 11.30.19, updated: 06.24.26

Fully utilizes TS2068 Extended Color Mode. Select Paper, Ink and Border Colors. Draw and Erase freehand with pen or brush strokes. Features precision circle and line entry functions. Intermix text with graphics. Keep two screen drawings in memory at once. Save & Load screens to cassette tape. Prints a screen image to your Timex printer.product, orig pub: 05.31.26, updated: 06.24.26

The Westridge Communications 2050 modem allows you to communicate through your telephone with other computers and information sources. With this modem and the included MTERM I cassette software, you can connect to other computers, bulletin boards and services like THE SOURCE, CompuServe, DOW JONES, and MCI MAIL. Features Prints displayed screens on the TS2040.product, orig pub: 11.30.19, updated: 06.23.26

This informal group has twice a month meetings online (via Zoom). Like in-person user group meetings, we have guests, talk about our projects and a wide array of computing topics. This group has its origins in the Yahoo TS 2068 Group, which migrated to groups.io when Yahoo Groups shut down. Join Our Email List Sign…usergroup, orig pub: 04.21.23, updated: 06.14.26

President: Frank DavisVice-President: Paul HolmgrenSecretary: Willie JonesTreasurer: Carol Davisusergroup, orig pub: 02.01.20, updated: 03.29.26

President: Michael E. CarverVice-President: Bill DunlopSecretary: Jack ArmstrongTreasurer: Rod GowenLibrarian: Gaylen Benchusergroup, orig pub: 02.01.20, updated: 03.13.26

Presidents: Neal Schultz, Bill HeberleinVice President: Bill Heberlein, Neal SchultzSecretary: Lloyd Dreger, Bud DankertTreasurer: Judy Frohboese, Dick CulticeDirector of Education: Dick Culticeusergroup, orig pub: 02.01.20, updated: 03.12.26

This music player for the TS2068 reads ProTracker 2 / Vortex Tracker II songs and plays them through the onboard AY-3-8912.video, orig pub: 05.17.26, updated: 07.05.26

Two newcomers join: Charlie Day, who bankrolled a Sinclair QL writing BASIC as a teen, and David Laffineuse, a Florida collector of 80 machines who fried a 2068 with a DivMMC.video, orig pub: 07.05.26, updated: 07.05.26

David's Claude-built "Defender meets Choplifter" runs in Timex 8×1 color, a drop-in SCLD replacement is in the works, an AI indexed 109 meetings and 13,000 emails — plus Bill Miller's giant plastic "control center."video, orig pub: 07.05.26, updated: 07.05.26

Fort Worth user group history, semiconductor fab war stories, the 2060 expansion board project, a Baudot telegraph keyboard interface, Joust for the ZX81, and a rescued tape.video, orig pub: 05.17.26, updated: 05.17.26

We look at the N-Go Spectrum Next clone from Spain, a PC-8300 ZX81 clone, and various tools for converting images to retro computing styles.video, orig pub: 05.17.26, updated: 05.17.26