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Through numerous pieces of correspondence, I’m finding that the world of Spectrum Emulator-dom is far larger than first expected. Groups around the country are using various methods to achieve this goal. The fact that not one, but many methods are being used, suggests that each has advantages and disadvantages not in the others. We’ll explore those advantages and disadvantages. Before going on, I’d like to say that after having taken my first steps with the Spectrum Emulators, I’m totally hooked. Those considering doing the same should be warned!
For those just tuning in, a Spectrum emulator is a piece of hardware that makes a TS2068 act very much like its British counterpart, the ZX Spectrum. This will allow most, (but not all) of the thousands of available Spectrum programs to run on our support-hungry TS2068’s. (TS 1000 users should be pleased to know that they need no emulator to run British ZX-81 software).
The simplest method of Spectrum emulation is to open your TS2068, unplug the home ROM (be careful!! There are two ROMs in there!) and plug in a Spectrum ROM. Since this will prevent a lot of your TS2068 software from working, it’s not a step to take lightly. Note that you can’t do a lot of switching back and forth, since the ROM pins will start breaking off if they’re plugged and unplugged too many times. Still, with TS2068’s selling for $99 in New York City, a lot of SINCUS members have bought “spare” computers. Rather than let that extra machine pather dust, it can be put to work as a pseudo-spectrum (or something like that). You won’t get the two machines mixed up; TS2068’s initialize and then put two copyright messages on the screen, while Spectrums put up only one.
Spectrum ROMs are available for $20.00 plus $1.00 shipping and handling from Foote Software, P.O. Box 14655, Gainesville, Florida 32604. (ED. NOTE-a contact on Compuserve indicates Spectrum ROMs are available from England for $7.00-more at the October meeting). If you’ve already got a spare TS2068, this is the cheapest way to own a “Spectrum”.
Here’s a warning. While there are dealers like the one above, who sell Spectrum ROMs as just that, some dealers may be less honest. Some unscrupulous characters out there mig htadverise Spectrum emulators, and just be shipping ROMs. Beware of those offering emulators at “rock bottom prices”, and be sure you know what you’re getting before you send any money.
A second type of emulator is a small printed circuit board that’s fitted to plug into the TS 2068’s home ROM socket, and which holds both the TIMEX and the Spectrum ROMs, selected by a switch. By changing the switch setting, you can go from the TS2068 to the Spectrum mode, and back. This method is far more versatile, but we mustn’t expect to get something for nothing. For $54.95, G. Russell Elctronics, R.D.#1, Box 539, Centre Hall, PA 16828 will sell you a ROMSWITCH, which appears to function as this second emulator type. I have not tried (nor even actually seen) this product, but the advertisement suggests that the mode is selected by means of a magnetic read switch. This very clever method would allow you to select the Spectrum or TS2068 mode by place (or not placing) a magnet on top of your TS2068!
Although I might change my opinion if I used an actual ROMSWITCH, I fear that bumping the magnet would be an ideal way of crashing the computer; I’d be terrified of placing my hands anywhere near it! Another possible problem is that magnets can erase your program tapes! Using this method, you would have to develop your work habits so that you always know exactly where the magnet is when you’re not using it! The magnet and your tapes should never be placed in the same spot even for an instant.
Please understand that the above paragraph is based totally on deduction. I’ve not used the device, and it’s designers may have found some clever way of solving those problems that I’m not aware of. Nevertheless, I feel obligated to comment on potential problems, as well as to correct any errors in future editions of this column. Anyone with actual experience with this product is invited (nay, pleaded) to contact me, care of this newsletter.
Emulator methods that use an actual Spectrum ROM sometimes have trouble initializing when the power is turned on. To correct this minor inconvenience, simply shut the power off, and turn it on again. The later production runs of the TS2068 reportedly have trouble 20 per cent of the time, while earli erruns have trouble much more frequently.
An advantage of both of the above methods is that (unlike the method I’m about to describe) they don’t tie up the TS2068 cartridge port. Although TIMEX cartridge software will not work with the Spectrum ROM, and there’s unlikely to be any great quantity of cartridge software produced to work with the Spectrum ROM, it should be possible to produce machine code cartridges that can work with it. Anyone who plans to do this will naturally select one of the previous two methods.
A third type emulator is built into a printed circuit card that plugs into the TS2068 cartridge port. When turned on, the machine first initializes normally, momentarily showing the two copyright notices, then it initializes again, leaving only one Sinclair copyright message. I’ve tried out one of those, and it works perfectly every time. Apparently the first in i-tialization by the TIMEX ROM clears up the initializati on problem associated with the Spectrum ROM.
This method has the advantage of not requiring you to open your TS2068, risking damage to the innards. Disadvantages include the need to plug and unplug the cartridge to switch modes (the connector in the cartridge port will not last forever), the need to tie up the cartridge port in the first place, and the fact that this emulator is the most expensive. Unfortunately, in order to make the cartridge self-starting, four bytes of the Spectrum code had to be changed. This means that the relatively cheap Spectrum ROM had to be replaced with an expensive 16K x 8, 27128 EPROM.
This runs the price up to $60.00, but you get a lot more than just an emulator. The group that produces them is helpful ,cooperative, and enthusiastic, and can provide a lot of support for their emulator users. The literature I received includes a huge list of Spectrum programs that run with their emulator, as well as some that don’t need an emulator, a few that only work with a Spectrum ROM, and a few that don’t work at all. They also provided a lot of information on British publications and US dealers of Spectrum products. (Note that the US dealers are charging 2-3 times what you’d pay by ordering directly from England).
It becomes quite clear that these people are not just merchants trying to sell a gadget, but people who thoroughly enjoy theirs and are determined that their customers share that enjoyment.
By the way, “they” are the TRIANGLE SINCLAIR USERS GROUP. Write to Douglas F. Dewey, 206 James Street, Carrboro, NC 27510. They also publish an excellent newsletter, which should keep us all up to date on the latest news in emulator dom. Membership in the group which includes the newsletter, is $10 per year, and it’s worth it.
To date, I’ve built three plug-in cartridge circuits, and two have been run as emulators. From work with them, I’m sure an interesting thing will happen if a plug-in cartridge is built with a cheap Spectrum ROM. When the TS2068 is turned on, the ROM will remain inactive, and the machine will “come up” as a TS2068. By loading and running a small software “bootstrap” it will be possible to switch back and forth between Spectrum and TS2068 modes. I have the soft ware bootstrap and I’ve simulated the Spectrum ROM with other memory circuitry.
Although loading the bootstrap is a small inconvenience, it’s also a tremendous advantage. The cartridge need not be plugged/unplugged to switch modes, and no magnets are needed; the switch is in the software. As an added benefit, the TIMEX ROM performs the first initialization, so the simulated Spectrum ROM never has trouble starting up. Best of all, it works perfectly, every single time!
Unfortunately, it’s taken more words than I had wished to describe the latest in emulators. I’ll have to hold off until next time for more words on British vendors and publications. Hopefully, in the next couple of months, I’ll also have word on some new British ZX-81 (TS1000) games that use the high resolution tricks we’ve seen demonstrated at SINCUS meetings.
Speaking of SINCUS meetings-see you all there!!!