--- title: "Spectrum Emulator" type: "article" slug: "spectrum-emulator-2" url: "http://localhost/article/spectrum-emulator-2/" markdown_url: "http://localhost/article/spectrum-emulator-2.md" published_at: "2023-01-15T03:56:56+00:00" modified_at: "2026-08-01T23:47:15+00:00" featured_image: url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg" excerpt: "One of the biggest drawbacks of the 2068 is the selection of software available for it. Timex pulled out a bit too soon before a good selection of software became available. With the project I describe here, You can run many Spectrum (48K) programs on your 2068 (ones that normally don't run on your 2068)!…" category: - name: "SUM" slug: "sum" taxonomy: "category" url: "http://localhost/category/periodicals/sum/" post_tag: - name: "Best of Timex/Sinclair 2068 Articles and Documents" slug: "ts2068best" taxonomy: "post_tag" url: "http://localhost/tag/ts2068best/" - name: "Hardware project" slug: "hardware-project" taxonomy: "post_tag" url: "http://localhost/tag/hardware-project/" - name: "TS 2068" slug: "ts2068" taxonomy: "post_tag" url: "http://localhost/tag/ts2068/" model: - name: "Timex/Sinclair 2068" slug: "ts-2068" taxonomy: "model" url: "http://localhost/model/ts-2068/" indiv: - name: "Joseph Williamson" slug: "joseph-williamson" taxonomy: "indiv" url: "http://localhost/indiv/joseph-williamson/" publication_r: id: 10242 title: "SUM" type: "periodical" url: "http://localhost/periodical/sum/" authors: "Joseph Williamson" authors_r: - name: "Joseph Williamson" slug: "joseph-williamson" taxonomy: "indiv" url: "http://localhost/indiv/joseph-williamson/" pages: "13-15" related_articles: - id: 44684 title: "Spectrum Emulator Revisited" type: "article" url: "http://localhost/article/spectrum-emulator-revisited/" archive_link: false archiveurl: "https://archive.org/details/BestOfSUM/page/n13/mode/2up" --- # Spectrum Emulator One of the biggest drawbacks of the 2068 is the selection of software available for it. Timex pulled out a bit too soon before a good selection of software became available. With the project I describe here, You can run many Spectrum (48K) programs on your 2068 (ones that normally don’t run on your 2068)! **WARNINGS** Do not attempt to make this your first project. It requires going inside the machine and removing an IC chip and replacing it with the board described here. Also remember that going into your machine probably will void your warranty. Basically, what we’re doing is replacing the 2068 ROM with the Spectrum ROM, which is all that you would have to do if you don’t want to change between the two operating systems very often. The board that I describe here switches between the two ROMs so that you have immediate access to both operating systems at a flick of a switch. The circuit board and schematic along with the pictures show the board, where it goes and how to make the necessary connections. Pin 27 is the chip select for the NEC ROM used by Timex and later model Spectrums. An earlier Hitachi Rom was used in the Spectrum and both machines allow the use of either ROM (the NEC and Hitachi ROMs have their pin 27 and pin 20 reversed). I take into account only the NEC ROM which should be the only one found in current 2068’s and what is presently available for the Spectrum. The way you can tell is by the wire links used to the left of the Timex ROM (U16). The NEC ROM uses W1 & W2 shorted, and the Hitachi ROM uses W3 & W4 shorted. The ROMs are wired in parallel except for pin 27, which is wired as shown in the schematic. ROMCS (active low) comes from the ULA chip and selects the ROM when needed by going to a low state (0V). The switch selects the desired ROM by connecting ROMCS to that chip. The resistors, R, pull the unused ROM up to a high state (5V) so that it will remain inactive. Although probably not needed, C takes care of any transients (I feel better with it there). I used 10K ohm resistors, but anything from 4.7K to 10K can be used. Capacitor C can be 0.1 uF to about 4.7 uF, preferably tantalum. [![Image](http://localhost/wp-content/uploads/2023/01/spectrum-rom-1.png)](http://localhost/wp-content/uploads/2023/01/spectrum-rom-1.png) [![Image](http://localhost/wp-content/uploads/2023/01/spectrum-rom-2.png)](http://localhost/wp-content/uploads/2023/01/spectrum-rom-2.png) Care must be taken when removing the chips and inserting them. The pins bend very easily and the chips are very static sensitive. One of the chips (I chose the 2068 ROM) needs to be mounted from the foil side and soldered in place. The other chip can be socketed. Room prevents the foil side ROM from being socketed. Making the board can most easily be accomplished by taking the layout given here and having it copied onto clear acetate and then using a photo sensitive PC board (available at your local electronics shop), expose with your clear acetate copy and develop and etch following the instructions given with the process. All parts should be readily available. BEFORE YOU START ANYTHING, UNPLUG AND DISCONNECT EVERYTHING FROM THE COMPUTER. To assemble the board, first remove the seven screws securing the bottom of the computer and carefully lift the top up till you see the keyboard connector, then carefully pull out the flat lead wire from the socket on the board. Now remove the Timex ROM, marked U16, (be careful not to bend any of the leads) and place it in a piece of static foam. [![Image](http://localhost/wp-content/uploads/2023/01/spectrum-rom-3.png)](http://localhost/wp-content/uploads/2023/01/spectrum-rom-3.png) From the picture, you can see that pins are required to stick down from the foil side to slide into the socket present on the 2068 circuit board. I used a three level 28 pin wire wrap socket and stuck it through the board about 1/4″ and soldered them in place before clipping the leads from the top, through the center set of 28 pin holes. Next, install a 28 pin LP socket into the holes just offset to the right of the pins mounted before. Now stick the protruding pins into a piece of anti-static foam and mount the Timex ROM into the remaining holes taking care to allign pin 1 with the hole marked pin 1. Solder the resistors and capacitor in place and run three wires to a SPDT switch with the ROMCS wire going to the common of the switch and the CS1 & CS2 wires going to the outer tabs of the switch. I mounted the switch in the rear of the computer and physically set it so that the up position is for the Timex ROM. Check to make absolutely certain that there are not any solder bridges between any of the traces on the board. Once you are sure that everything is OK, remove the anti-static foam from the pins and insert into the ROM socket on the 2068 board taking care to align pin 1 in the proper place (facing from the front of the computer, pin 1 will be left rear of the socket. The chip facing down will be to the left, as in the picture. Insert your new ROM into the socket of the Spectremulator with pin 1 in the same position as just mentioned. Mount the switch in a convenient place. Be carefull drilling into the case. For the top to sit down evenly again, a plastic tab that hangs down from under the keyboard must be clipped back about 1/8-1/4″. Before re-assembling the computer, go ahead and connect the power and monitor and turn it on. In the Timex ROM position, the familiar copyrights show up as usual. Allways turn off the computer before switching the ROM switch. Now try it in the Spectrum ROM position. Only the Sinclair copyright should show up! If one or both positions produce nothing but a crash, turn off the computer and examine your board more closely for shorts or breaks in the traces. Once you have it working properly, reassemble the computer taking care to gently re-insert the keyboard connector. Once you are in the Spectrum mode, You will notice some differences in the operating system. FREE has been changed to: ~, STICK is now: |, ON ERR gives only: {, SOUND gives only: }, RESET gives only: @, and the word DELETE no longer appears. (Several of these characters do not print on our daisywheel printer.) Also the annoying stop-before-delete at every semicolon and line number is gone. Even though these commands are gone, they can still be used or made using IN & OUT and short routines. The joysticks still work with programs like Flight Simulator and Cyberzone while in the Spectrum mode. Sound can also be made using OUT and POKE (more on this next month). The command cartridge port does not work when in the Spectrum mode either. Otherwise, everything works exactly the same. Things that do work include the 2040 printer and the 2050 modem. As far as software for the Spectrum is concerned, we have tried about seven that don’t work on the 2068 but do work fine with the 2068 with the Spectrum ROM inside. They include all the software from Tasman (Tasword Two, Tasprint, & Taswide), Microprint 85 (you must CLEAR 65535 before loading) Pengy, Pool, and Cascade (contains 50 programs—some of these do run on the 2068). We have not found any that don’t work yet. Just make sure that the software is for a 48K Spectrum. We will continue to order (and rent) software from Europe and keep you informed as to what we have found to work and is worth having. The Spectrum ROM is available from FOOTE SOFTWARE (see ad this issue) for $20. For software, check any British computer magazine you can get. They generally all list some titles. [![Image](http://localhost/wp-content/uploads/2023/01/spectrum-rom-4.png)](http://localhost/wp-content/uploads/2023/01/spectrum-rom-4.png) With this addition to the 2068, you can open up a whole new avenue of support for your computer. With this we hope to be able to determine which peripherals for the Spectrum will operate on our 2068s including the microdrives now available in England!