The Plus D Corner, Part 4

The Plus D Corner, Part 4

Hello everyone! Today I want to report on my experiences with the Plus D in connection with various Spectrums. I will also discuss some hardware expansions, meaning what works with the +D and what does not. This will be a help especially for +D beginners, but I hope that I can tell the "old foxes" among you something new as well. There have been individual contributions in various publications on today's topic in the past. I do not want to repeat everything here; instead, if appropriate, I will provide relevant pointers on where to find detailed information. Naturally, I cannot cover every possible hardware combination, but I do have a few things to share. Let's get started:

Part I: Which Spectrum works with the Plus D and what must I consider?

Basically, the Plus D works on every Spectrum in every mode. That means 48K or 128K. Exceptions (the +3!) confirm the rule. Here is a list with relevant notes:

(Note from LCD: If you want to use graphics, please provide them as screens, Guido, otherwise I cannot include them here! I am copying this from the manual, for other graphics I would have to guess!)

3) When using the +D in +3 Basic first boot your system disk using RUN then type the following line:
POKE @4426,16: POKE @4427,92
Please note that there are one or two slight anomalies due to the fact that +3 basic is expecting a 3" drive.

• Spectrum 16K: I cannot say whether the +D works on a 16K Spectrum (yes, those existed too!). There is actually nothing against it, but who still uses a 16K Spectrum today?
• Spectrum 48K: No problem. The lack of a reset button is annoying. After disconnecting from the power, you have to reboot the DOS every time.
• Spectrum Plus: No problem.
• Spectrum 128 Plus: No problem in either mode.
• Spectrum +2: I have never owned a +2 (the gray one), but I am sure that the +D works here in both modes as well.
• Spectrum +2A/B: As is well known, the expansion port here is different from the other Spectrums. Only an adapter (Fixit) or an internal modification helps here. Further problems exist in 128K mode because of the +3 DOS. Two special +D POKE commands help here. See the +D manual from Datel. Incidentally, the old MGT manual lacks references to the +3 and +2A/B. Problems with the special RAM DISC syntax remain, however, despite the POKEs (see Part 3 of the Plus D Corner under the section "BACKUP UTILITY"). It is best to install a 128K Sinclair ROM. That is really simple. However, the printer interface of the +2A/B can then no longer be used. No great loss, because the +D has its own printer interface.
• Spectrum +3: The +D and the +3. A quite exotic and, above all, the most difficult +D/Spectrum combination. That is why this section is quite long. For the sake of completeness, however, the +3 cannot be left out. What I just said about the +2A and +2B also applies in principle to the +3. Now comes the catch: the POKEs mentioned above for the 128K mode (+3 DOS) are not very useful on the +3. The computer crashes quite often. The +D manual already points out that anomalies can occur because the +3 DOS expects a 3" drive. I suspect the problems lie with the +3's disk controller, which is missing on the +2A/B. I tested the whole thing more intensively recently. The reaction of the +3 was different with almost every attempt. If you boot the DOS in 128K mode (+3 DOS), the computer crashes afterward. Mostly you end up in the start menu of the +3. Sometimes an error message appears and the whole "box" freezes. Or the red LED of the +D flashes like crazy. In any case, the whole thing has no system.

Some +D 128K programs run on the +3 if you switch from +3 mode to 48K mode with the SPECTRUM command. For example, Tasword Plus Two (+D version). Poking is not necessary. The following also works: switch to 48K mode with the SPECTRUM command. Then boot with RUN, poke, and return to 128K mode (+3 DOS) with RUN USR 23354. Now you can work with the special +D commands without the computer crashing. So, for example, CAT 1 or LOAD P1. But after a NEW, everything is lost again. The DOS is still in the +D, but if I go back into the +3 DOS via the menu, CAT 1 etc. no longer work. The system crashes again (Already tried USR 0 mode? LCD).

I ask myself whether this is the same for other +3s. Well, anyway, I don't think the whole thing is very bad. The +3 is very uncommon here. Those who then also want to operate a +D on the +3 in 128K mode (+3 DOS) should be very few. So, what I wanted to say is: it is not worth breaking your head over it any further. The few who are affected should install a 128K Sinclair ROM (switchable). With that, you are rid of all worries. I am very satisfied in any case. I work almost exclusively with the +3. An old 128K is connected here for emergencies. But mostly I only use it for any slave work (copying, etc.) to save time. I cannot remember needing it because something didn't work on the +3 (as I said, with switchable ROMs). It always depends on what you want to do. My +3 recently gave up the ghost and since I am not a DIY expert, I sent it to SINTECH for repair. Since it was there anyway, I had it converted right away. Anyone who wants to connect a +D to the +3 and does not want to do without the possibilities of a 128K Spectrum should have a 128K Sinclair ROM with a switch installed, as I already mentioned. In principle, you now have two Spectrums in one, and if you want, four disk drives. One internal +3, one external on the +3, and two on the +D. That's crazy, isn't it? But it works! In any case, you can now switch between the ROMs depending on your needs and application. Unfortunately, with my switch, you cannot simply switch in the middle of a program. That leads to a crash. A RESET must therefore be performed. It is best to switch on the desired ROM before turning on the computer. Another (simpler) conversion option would be to simply swap the ROM as with the +2A/B. However, you can then no longer use the internal drive of the +3. The +3 DOS is then missing.

An internal conversion of the expansion port to the Sinclair standard is also possible. However, you should note that you can no longer use a Multiface-3. With the Fixit, you are more flexible, although that is actually not a clean solution. For the sake of completeness (it actually has nothing to do with the +D), I would also like to mention the conversion of the joystick ports. This allows you to use standard joysticks (Atari standard).

Part II: Which hardware expansions work with the +D and what are the conversion possibilities if it doesn't work by default?

First of all, we must note that the +D does not have a pass-through expansion port. That means, in principle, one must ensure that a second hardware expansion has a pass-through expansion port. Another possibility would be a special adapter, so I mean a "bus doubler". That would be, for example, the CURRAH SLOT. It is designed so that after plugging it in, you have two ports available. One pointing up, one pointing out the back.

This can lead to further problems. The case from the ZX Spectrum+ onwards is higher than the "rubber-Specci". My JSS joystick interface (without a pass-through expansion port), for example, cannot be connected for this reason. I have no further experience here. The other hardware expansions I use luckily have a pass-through port and are fully +D compatible.

If the hurdle with the expansion port has been overcome, that does not mean that the second hardware expansion will also work with the +D. But I think I'm not telling you anything new there. That is a general problem with the ZX Spectrum or computing in general. Below, I would like to share my experiences and knowledge. As I said, my list is certainly not exhaustive. But that would probably be asking too much. Let's get started:

• Printer Interface: The +D has its own printer interface. This is supported by many programs. Therefore, a special printer interface is, in my experience, not necessary. Older software often has a Disciple option for printing. This can, of course, also be used. But what if you have software that only supports the "Kempston E" or the "LPRINT 3", for example? I have no experience here. But what I write below regarding the +2A/B or +3 could also be of use in this case. Practice makes perfect! The printer interface on the +2A/B and +3 can also be used if a +D is connected. Depending on the application, however, conflicts can logically occur. But the possibilities for printing are so complex that one cannot make a generally valid statement here. It depends on what you want to do. For example, printing graphics, an LLIST, printing from an application program, or something else. If you want to use the internal interface of the +2A/B or +3 for printing and there are problems, you can deny the question in the +D system installation program of whether you want to use the +D printer interface. If you boot such a system file, the printer interface of the +D is ignored. Another possibility would, of course, be not to boot the +D at all. That has the same effect, but then you logically cannot perform any disk operations with the +D. By the way, with "POKE @11,0" you can activate the +D printer interface and with "POKE @11,1" switch it off again. See also the +D manual under "OTHER TYPES OF PRINTERS".
• Other Disk Interfaces: Usually does not work. See, however, the section "Miscellaneous" regarding this.
• Videoface: No problem. The +D is fully supported! You can find information about the Videoface in the Proficlub issue 05.94 on pages 8 and 9 (German instructions by Heinz Schober).

Multiface

There is a special 128K version for the Disciple interface (the predecessor of the +D). As far as I know, only this Multiface version works on the +D. Incidentally, according to the Multiface manual, this Multiface-128 also works on the 48K Spectrum. There is also more than one version of the Multiface-1. In any case, my Multiface-1 does not work together with the +D. After pressing the red button, my Spectrum 128 crashes. Naturally, I tested this in 48K mode. In 128K mode, the Multiface-1 does not work as a matter of principle. The Multiface-3 also does not work together with the +D. Naturally, I tested this on a +3. See also: Proficlub 01.96, page 10 onwards (MF-1 and MF128 by H.Schober), Proficlub 10.96, page 14 (report by me), Computer Kontakt 6-7/86, page 14 onwards (presentation of Multiface-1), Computer Kontakt 10-11/86, page 25 (modified Multiface-1).

Joystick Interfaces

On the last ZX Spectrum computers built by Amstrad (+2, +2A/B, and +3), joystick ports are integrated. These are supported by most games. As I already mentioned, you can convert the joystick ports to Atari standard or use an adapter cable. (Attention! Some games, especially from Russia, NEED a Kempston interface. LCD.)

More problematic are the old ZX Spectrums (16K or 48K with rubber keyboard, 48K+, and 128K+) from Sinclair. These have no joystick port. You need an external joystick interface. There are quite a lot of these. Joystick adapters with a pass-through expansion port should actually all be +D compatible. I have already mentioned the experiences with my "JSS" joystick interface (without pass-through expansion port) above.

What other options do you have? My Multiface-1, as I said, is not +D compatible, but it does have a pass-through expansion port and a joystick port (Kempston compatible). I can easily use this Multiface as a joystick interface together with the +D. Unfortunately, not every Multiface has a joystick port.

Mouse

I have never used a mouse on the Spectrum, so my remarks here are purely theoretical. Furthermore, everything I have read about it so far is very contradictory. For instance, there is a user who had problems running a Kempston Mouse interface together with the +D. From other sources I hear that it works without any problems. In an older issue of FORMAT (11.94, page 15), someone is looking for a Kempston Mouse in the Disciple/+D version. Apparently, that is the solution to the contradictory statements.

What other mice do we know of? There is also the AMX Mouse. This is presented in the magazine Computer Kontakt 8-9/86, page 10 onwards. It is very likely not +D compatible. The Genius Mouse is said to be compatible with the Kempston mouse. Until recently, the Genius Mouse was still offered by Datel. Datel no longer offers the +D, and as far as I know, the other Spectrum products are no longer sold either (as of 1996). Regarding compatibility, there are contradictory statements here too. See: FORMAT 11.94, page 35 / FORMAT 08.95, page 38 / FORMAT 07.96, page 25 (A Genius At Work, Part I) / FORMAT 08.96, page 23 (A Genius At Work, Part II) / Computerflohmarkt 01.97, rubric 3840.

Supposedly, there is also a version of the Genius Mouse with a pass-through bus. Otherwise, you need a CURRAH SLOT or another Y-connector, meaning the already mentioned "bus doubler". Here again, space problems can occur due to the Spectrum cases (from the Spectrum+ version onwards). In this case, you cannot plug in the mouse interface.

As you can see, the topic of mice is a case of its own. Who uses an off-the-shelf mouse interface together with the +D and can report on their experiences?! I cannot and do not want to go into detail here about the homebrew mouse interfaces that have occasionally been described in club magazines and publications in the past. That would certainly go too far. But perhaps that is precisely the way to get a mouse that runs smoothly together with the +D?

Interface I

Well, who would do something like that? Such a combination does not seem very sensible to me. Nevertheless, there are people who have already done this or want to do it. The whole thing really only made sense back in the transitional phase when many upgraded from their "old" disc system to the newer +D. Perhaps to transfer data and programs. Often people also had software that only ran on the old disc system. Nowadays, pretty much all the software your heart desires is available for the +D. There are also many conversion programs and utilities.

I would like to explicitly warn against "the proof of the pudding is in the eating"! When trying to run multiple floppy systems on the expansion port, quite a bit of hardware has already "gone up in smoke"! As a rule, it doesn't work without hardware modifications. There is experience with the Beta Disk interface. See under "Miscellaneous".

I have already reported on my experiences with the +3 floppy drive in connection with the +D. See above under "ZX Spectrum +3".

Miscellaneous

It is also worth mentioning that by modifying the +D, you can make it switchable. This makes it possible, for example, to connect the Interface I or the Beta Disk together with the +D to a Spectrum. See Proficlub issues 6.91 (page 9), 9.91 (page 10 top), and 11.91 (page 11). In addition to general info, there is also a modification guide there.

For hobbyists, the +D circuit diagram in Spectrum-Userclub-Info 4.94 and the +D RAM buffering in SUC-SESSION 10.94 (page 8) would also be interesting.

As you can see, I have mentioned various publications. Anyone who does not have one or the other, but is still interested, is welcome to contact me (please: include return postage). The reports from FORMAT, however, are all in English.

Believe it or not, I turned almost my entire "Spectrum archive" upside down for this article. Even if I (unfortunately) did not find much for this report, it was definitely a very interesting trip down Spectrum memory lane. The fact that I kept getting stuck reading other interesting reports while looking for usable material is certainly just one reason why the fourth part of the +D Corner was completed so late. In any case, I was on the verge of "data overload". Please bear with me!

With a 4 Out of Memory, 0:1, I would like to say goodbye for today.

Guido Schell, Auf dem Stocke 37, 32584 Löhne, Telefon 05732 8769

(It was damn tight with memory this time, that's why I had to reformat the text, sorry Guido that it now look