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      <title>Hardware - World of Spectrum</title>
      <link>https://worldofspectrum.org/forums/categories/hardware/p135/feed.rss</link>
      <pubDate>Mon, 22 Apr 2024 12:14:49 +0000</pubDate>
         <description>Hardware - World of Spectrum</description>
   <language>en-CA</language>
   <atom:link href="https://worldofspectrum.org/forums/categories/hardware/p135/feed.rss" rel="self" type="application/rss+xml" />
   <item>
      <title>Memory management in new IDE interfaces</title>
      <link>https://worldofspectrum.org/forums/discussion/21448/memory-management-in-new-ide-interfaces</link>
      <pubDate>Fri, 18 Jul 2008 21:04:13 +0000</pubDate>
      <dc:creator>maskenlos</dc:creator>
      <guid isPermaLink="false">21448@/forums/discussions</guid>
      <description><![CDATA[Hi all,<br />
<br />
I have a question concerning the memory (RAM) management of the new mass storage devices like ZXCF+ or others.<br />
<br />
The mostly come with 512kb or 1024kb. My Question is now, how is the memory paged in or out or. How does the Speccy address the memory? Is this done in kind of memory areas or something else? My be there is somewhere a web side which explains this in details?<br />
<br />
Thanks and best regards<br />
<br />
Maskenlos]]></description>
   </item>
   <item>
      <title>+2A and +2B models</title>
      <link>https://worldofspectrum.org/forums/discussion/21507/2a-and-2b-models</link>
      <pubDate>Wed, 23 Jul 2008 10:07:21 +0000</pubDate>
      <dc:creator>PopoCop</dc:creator>
      <guid isPermaLink="false">21507@/forums/discussions</guid>
      <description><![CDATA[What's a difference between Spectrum +2A and +2B models?]]></description>
   </item>
   <item>
      <title>Spectranet copyright info for Winston</title>
      <link>https://worldofspectrum.org/forums/discussion/21513/spectranet-copyright-info-for-winston</link>
      <pubDate>Thu, 24 Jul 2008 07:07:48 +0000</pubDate>
      <dc:creator>chev</dc:creator>
      <guid isPermaLink="false">21513@/forums/discussions</guid>
      <description><![CDATA[Amstrad doesn't own the copyright in the IF1, it's still owned by Sinclair Research Ltd.]]></description>
   </item>
   <item>
      <title>Joysticks on Amstrad boards</title>
      <link>https://worldofspectrum.org/forums/discussion/21494/joysticks-on-amstrad-boards</link>
      <pubDate>Tue, 22 Jul 2008 11:50:37 +0000</pubDate>
      <dc:creator>emleymoor</dc:creator>
      <guid isPermaLink="false">21494@/forums/discussions</guid>
      <description><![CDATA[Never mind the oddly wired connectors for this post... as we all know, the joystick ports on the +2 and +3 are Sinclair Interface II equivalents.<br />
<br />
Is this something fixed in the hardware, or would it be possible to make some kind of alteration that could switch them in software so that one is a Kempston (pure, so that it is compatible with Caesar the Cat) and the other is a Cursor? Of course, this would need a switching command added - so it's the sort of thing that would need a new ROM.<br />
<br />
Is this technically possible?<br />
<br />
(I remember on the Opus Discovery 1, you could enable and disable the Kempston interface with a FORMAT command on the "j" channel.)]]></description>
   </item>
   <item>
      <title>Copy interface ROM content to Ram</title>
      <link>https://worldofspectrum.org/forums/discussion/21458/copy-interface-rom-content-to-ram</link>
      <pubDate>Sat, 19 Jul 2008 12:19:17 +0000</pubDate>
      <dc:creator>maskenlos</dc:creator>
      <guid isPermaLink="false">21458@/forums/discussions</guid>
      <description><![CDATA[Hi all,<br />
<br />
I have a very rare logitec centronics and disc interface. To save its ROM content I would like to copy it Ram and store it somewhere. How can I do this? Small MC routine to copy from Ram area to Ram area could be sure found somewhere (I am not very familiar with MC). But How to be sure that the Interface ROM is paged in during the copy process!<br />
<br />
Thanks for your  help!<br />
<br />
Regards<br />
<br />
Maskenlos]]></description>
   </item>
   <item>
      <title>Buzzing Spectrum</title>
      <link>https://worldofspectrum.org/forums/discussion/21477/buzzing-spectrum</link>
      <pubDate>Sun, 20 Jul 2008 22:03:15 +0000</pubDate>
      <dc:creator>carlinski</dc:creator>
      <guid isPermaLink="false">21477@/forums/discussions</guid>
      <description><![CDATA[Picked up a Spectrum + (48k) today at a car boot, for 3 quid:-P On the plus side it does work, however it does buzz pretty bad. What normally causes this and is it an easy task to sort myself?<br />
<br />
Also, on the rear i/o slot it has written in red "Upgraded", does this mean its a rubber key with the new casing?<br />
<br />
Thanks,<br />
<br />
Carl]]></description>
   </item>
   <item>
      <title>Tape loading issues - can anyone help?</title>
      <link>https://worldofspectrum.org/forums/discussion/21412/tape-loading-issues-can-anyone-help</link>
      <pubDate>Tue, 15 Jul 2008 08:40:35 +0000</pubDate>
      <dc:creator>Outraged Donkey</dc:creator>
      <guid isPermaLink="false">21412@/forums/discussions</guid>
      <description><![CDATA[Hi,<br />
<br />
I have just bought a +2 which has a problem. Whenever I try to load a tape the spectrum refuses to acknowledge what I am doing. I have tried in Loader and 48k Basic, but I can't even get the alternating red/cyan border. Instead the tape just runs with no effect.<br />
<br />
I have tried a tape I know loads (tested it on another spectrum), along with a few other tapes. I have also tried adjusting the screw between the tape desk and the tape controls.<br />
<br />
I also know that sound is getting to the television, as the BEEP command in Basic works fine. I've given the tape head a cursory clean but there doesn't seem to be much dirt there.<br />
<br />
Has anyone encountered this before? Is there a solution? Can I rig an external tape player to the +2 like I would with a 48k?<br />
<br />
Any help would be appreciated.<br />
<br />
Thanks]]></description>
   </item>
   <item>
      <title>Timing... in the CSS faq</title>
      <link>https://worldofspectrum.org/forums/discussion/21441/timing-in-the-css-faq</link>
      <pubDate>Fri, 18 Jul 2008 12:58:03 +0000</pubDate>
      <dc:creator>Winston</dc:creator>
      <guid isPermaLink="false">21441@/forums/discussions</guid>
      <description><![CDATA[I was looking at the CSS faq for something completely unrelated and noticed:<br />

<blockquote>

<div>Then the 192 screen+border lines are displayed, followed by 56 border lines again. Note that this means that a frame is (64+192+56)*224=69888 T states long, which means that the '50 Hz' interrupt is actually a 3.5MHz/69888=50.08 Hz interrupt. This fact can be seen by taking a clock program, and running it for an hour, after which it will be the expected 6 seconds fast. <b>However, on a real Spectrum, the frequency of the interrupt varies slightly as the Spectrum gets hot; the reason for this is unknown,</b> but placing a cooler onto the ULA has been observed to remove this effect.</div>
</blockquote>
<br />
Actually - it's very easy to explain, and it's a well known property of quartz crystal oscillators. Crystals aren't perfectly stable and do vary slightly with temperature. The ULA dissipating heat into the PCB and surrounding air will change the temperature of the nearby crystals, whose frequency will change slightly as a consequence. This will cause a slight variation which will be notable over a long enough period of time. Preventing the ULA from getting as warm as it does will of course prevent the crystals from changing temperature as much.<br />
<br />
The effect is noticable on PC clocks too - their accuracy will change depending on how warm the PC gets. Also happens with digital watches - they'll keep time slightly differently if you are not wearing it.]]></description>
   </item>
   <item>
      <title>PSU query</title>
      <link>https://worldofspectrum.org/forums/discussion/21383/psu-query</link>
      <pubDate>Sat, 12 Jul 2008 15:45:06 +0000</pubDate>
      <dc:creator>hypostomus</dc:creator>
      <guid isPermaLink="false">21383@/forums/discussions</guid>
      <description><![CDATA[Hi all, just one quick question. Are Spectrum PSU's compatible with ZX81's? I've just bought an '81 off of Ebay, which was sold as "working, but the power supply occasionally puts out low volts", so I'm feeling a bit cautious because I suspect it might bollock the machine if it does. Both PSU's are 9 volt, so they may be compatible but I don't if the amps produced are the same, hence the question.<br />
cheers<br />
Chris]]></description>
   </item>
   <item>
      <title>Upgrading to 48k</title>
      <link>https://worldofspectrum.org/forums/discussion/21160/upgrading-to-48k</link>
      <pubDate>Mon, 23 Jun 2008 08:54:34 +0000</pubDate>
      <dc:creator>jp</dc:creator>
      <guid isPermaLink="false">21160@/forums/discussions</guid>
      <description><![CDATA[I picked up a 16k Issue 2 Spectrum over the weekend, and I'd like to upgrade it to 48k.<br />
<br />
I've scanned an old <a href="http://www.drumfu.com/SinclairZXSpectrum48kExpansion-DavidReidElectronicsNZ.zip" rel="nofollow">upgrade guide</a> (2.16mb!) from an Auckland electronics company which lists the following components:<br />

<pre>8 x 4164/4564 [IC15-IC22]
1 x 74LS00    [IC24]
1 x 74LS32    [IC23]
2 x 74LS157   [IC25,IC26]
</pre>
<br />
Apart from sourcing the components, are there any caveats I need to be aware of? Cheers!]]></description>
   </item>
   <item>
      <title>Video fault with my spectrum, any ideas?</title>
      <link>https://worldofspectrum.org/forums/discussion/21369/video-fault-with-my-spectrum-any-ideas</link>
      <pubDate>Fri, 11 Jul 2008 08:03:57 +0000</pubDate>
      <dc:creator>shomenno</dc:creator>
      <guid isPermaLink="false">21369@/forums/discussions</guid>
      <description><![CDATA[Spectrum not working, CPU still seems to work, as the "BEEP" command still operates if machine is plugged in, however it no longer displays a picture on the screen. Not sure if the problem is with the TV cable or the Spectrum itself.<br />
<br />
Anyone have any ideas what maybe faulty?<br />
<br />
Thanks Shomenno]]></description>
   </item>
   <item>
      <title>Comcon problems</title>
      <link>https://worldofspectrum.org/forums/discussion/21100/comcon-problems</link>
      <pubDate>Thu, 19 Jun 2008 15:47:33 +0000</pubDate>
      <dc:creator>Neil L</dc:creator>
      <guid isPermaLink="false">21100@/forums/discussions</guid>
      <description><![CDATA[Can anybody please help?<br />
I've recently upgraded my rubber keyed 48k to a 128k toastrack.<br />
(?19.00 off Ebay with manuals,leads,tape recorder,3 games,a joystick &amp; interface. BARGAIN!)<br />
The only problem I'm having is that my Comcon Programmable Interface doesn't work on it.<br />
I've checked the original adverts on the WoS site and it says it works on the 48k,plus,128 &amp; 128 plus 2.<br />
I have even tried my other Comcon with no luck. But my (programmable) Cambridge Intelligent Joystick Interface works fine.<br />
Any help would be greatly appreciated.<br />
OK, back to filling my iPod with more 128k games.<br />
Cheers, Neil<br />
<br />
PS. Are the 128k Scart leads off Ebay any good?<br />
(I think my modulator is also on its way out as the screen goes squiffy when you move the lead by the socket and the picture gets worse the longer the speccy stays on!):???:]]></description>
   </item>
   <item>
      <title>Original DivIDE Snapshots</title>
      <link>https://worldofspectrum.org/forums/discussion/21170/original-divide-snapshots</link>
      <pubDate>Tue, 24 Jun 2008 11:24:16 +0000</pubDate>
      <dc:creator>garethrichardadams</dc:creator>
      <guid isPermaLink="false">21170@/forums/discussions</guid>
      <description><![CDATA[Hi all,<br />
<br />
Is there any way to:<br />
1. Load a game from the CF card connected to the DivIDE in tap/tzx format (to make sure multi-loaders still work)<br />
2. Take a snapshot while playing and save it to the CF card<br />
3. Be able to re-load the snapshot<br />
<br />
I've been looking at the different firmwares and can't work out if any of them let me do this??<br />
<br />
MDOS3 might. Apparently there's a way to convert tap to mdos3 files but I can't work out from the documentation if you can save and load snapshots.<br />
<br />
You can definitely save and load snapshots using +DivIDE but I can't find anywhere that says how to convert TAP to MGT (or whatever the format is!)<br />
<br />
Can anyone help?<br />
<br />
Thanks<br />
<br />
Gareth]]></description>
   </item>
   <item>
      <title>Accelerated spectrum?</title>
      <link>https://worldofspectrum.org/forums/discussion/21273/accelerated-spectrum</link>
      <pubDate>Tue, 01 Jul 2008 22:25:39 +0000</pubDate>
      <dc:creator>Hideki</dc:creator>
      <guid isPermaLink="false">21273@/forums/discussions</guid>
      <description><![CDATA[Hihi<br />
<br />
Has anyone managed to replace the Z80 in a spectrum with a Z80B?<br />
<br />
Just wondering if it'd be possible to have a couple of crystals switchable to run at standard or double speed?<br />
<br />
Not sure what other things depend on it mind hardware wise, could it affect video generation etc.?<br />
<br />
Thoughts welcome!]]></description>
   </item>
   <item>
      <title>ULA Replacement WORKS !</title>
      <link>https://worldofspectrum.org/forums/discussion/20694/ula-replacement-works</link>
      <pubDate>Sun, 18 May 2008 18:44:49 +0000</pubDate>
      <dc:creator>csmith</dc:creator>
      <guid isPermaLink="false">20694@/forums/discussions</guid>
      <description><![CDATA[Hi chaps.<br />
<br />
Lots of activity over the last couple of weeks, and _finally_ we have  <b>a working ULA replacement</b> !!<br />
<br />
The analogue components such as the cassette interface and video output are currently on a breadboard as they cannot be implemented within the Xilinx CPLD, but will end up on the same PCB.<br />
<br />
Details and photos here:<br />
<a href="http://www.zxdesign.info/ULAStableRunning.shtml" rel="nofollow">http://www.zxdesign.info/ULAStableRunning.shtml</a><br />
<a href="http://www.zxdesign.info/ulaReplacementWorks.shtml" rel="nofollow">http://www.zxdesign.info/ulaReplacementWorks.shtml</a><br />
<br />
<br />
I will be getting some PCB's made up professionally, probably from the same place as Winston.<br />
<br />
Cheers!]]></description>
   </item>
   <item>
      <title>How to load tzx files into REAL spectrum</title>
      <link>https://worldofspectrum.org/forums/discussion/20445/how-to-load-tzx-files-into-real-spectrum</link>
      <pubDate>Mon, 28 Apr 2008 16:42:11 +0000</pubDate>
      <dc:creator>patzik</dc:creator>
      <guid isPermaLink="false">20445@/forums/discussions</guid>
      <description><![CDATA[I have 2 zx spectrum computers, and have been trying to load tzx files into them. I have used several programs to convert them to wav files and them load them either via laptop or ipod into the spectrum but somehow I haven't been very succesfull.<br />
The normal programs seem to load ok, but anything with a 'speedloader' fail before even starting the 'speeded' part.<br />
<br />
Anyone have a succesfull way to do load games from a pc into the real spectrum?]]></description>
   </item>
   <item>
      <title>I/O on the Speccy - ideas/help wanted!</title>
      <link>https://worldofspectrum.org/forums/discussion/21275/i-o-on-the-speccy-ideas-help-wanted</link>
      <pubDate>Tue, 01 Jul 2008 23:00:18 +0000</pubDate>
      <dc:creator>gcallard</dc:creator>
      <guid isPermaLink="false">21275@/forums/discussions</guid>
      <description><![CDATA[I'd like an interface for the Spectrum that can control and monitor other items. I have a task in mind that would require:<br />
<br />
A: 4xbinary inputs (as in "on" or "off" x4 - this I can hack up with a Kempston interface and a joystick)<br />
<br />
B: 2xanalogue inputs (a Kempston mouse interface would be OK for this)<br />
<br />
C: 4x binary outputs (as in four independant OFF/ON controls).<br />
<br />
How should I go about building that?<br />
<br />
I can handle the transistor / relay circuits I need for correct power and such. I don't know how to interface such a device with a spectrum. I would like to have control using the IN and OUT commands in BASIC.<br />
<br />
In more detail, I want to be able to drive two motors (one for rotation and one for elevation) in both directions each. I want to use four micro switches to act as stop or home points. Ideally I would like a further 4 analogue inputs as well, though two would suffice at a push.<br />
<br />
The 2 analogue inputs mentioned above would be to provide a positional reference to the assembly driven by the motors attached to the outputs.<br />
<br />
How do I go about building such a circuit? Anyone have any tips?]]></description>
   </item>
   <item>
      <title>One's speccy is unwell, can anybody help?</title>
      <link>https://worldofspectrum.org/forums/discussion/21047/one-s-speccy-is-unwell-can-anybody-help</link>
      <pubDate>Sun, 15 Jun 2008 22:23:46 +0000</pubDate>
      <dc:creator>Yeti</dc:creator>
      <guid isPermaLink="false">21047@/forums/discussions</guid>
      <description><![CDATA[Hi chaps! This would be my first post here, so hello to all :smile:<br />
<br />
I've got a 128+ heatsink speccy that seems to have a display issue whereby after being powered up for around 30 mins or so, small horizontal lines about one character block wide seem to randomly appear then disappear across the screen. If I leave it powered up for longer it gets worse to the point where it randomly resets itself into 48 mode or displays more garbage on screen and crashes altogether :-?<br />
<br />
Would this have anything to do with the ula getting a bit too hot or maybe some of the ram going bad? I've heard these machines can sometimes get a bit toasty. I'm not too clued up hardware wise so any help would be greatly appreciated.<br />
<br />
PS. I've got it hooked up to my tv using the rgb port, and prior to the machine starting to act up I had a +D disk interface and Multiface 128 plugged in. Would this of maybe put a strain on the machine?<br />
<br />
Thanks in advance]]></description>
   </item>
   <item>
      <title>Loading Problem</title>
      <link>https://worldofspectrum.org/forums/discussion/21059/loading-problem</link>
      <pubDate>Mon, 16 Jun 2008 17:20:25 +0000</pubDate>
      <dc:creator>KJW</dc:creator>
      <guid isPermaLink="false">21059@/forums/discussions</guid>
      <description><![CDATA[Hi All<br />
I am hoping anyone could help me resolve a problem.<br />
My Spectrum 128k datacorder powers on and is fine, i have done the colour tests and they are fine, but when i load a game it starts to load and gives me 2 flashes of colour but then stops, i have treid loading many games to see if it was the tape but no joy, i also used a tape cleaner, again no joy.<br />
Would any of you guys have an answer to this, and possibly how to resolve it.<br />
Many Thanks in Advance<br />
Kenny :)]]></description>
   </item>
   <item>
      <title>Knackered keyboard on Speccy +</title>
      <link>https://worldofspectrum.org/forums/discussion/21240/knackered-keyboard-on-speccy</link>
      <pubDate>Sun, 29 Jun 2008 22:41:04 +0000</pubDate>
      <dc:creator>hypostomus</dc:creator>
      <guid isPermaLink="false">21240@/forums/discussions</guid>
      <description><![CDATA[Hi all, my keyboard is a bit shagged. The computer turns on, shows the copyright message, and then the space key appears to be stuck on continuously. I assume that this is due to a knacked membrane or possibly the ribbon cables connecting the keyboard to the circuit board.<br />
Anyway, the million dollar question...is there anywhere I can still send the thing to to get it repaired? This is assuming spare bits for it still exist of course.<br />
cheers<br />
Chris]]></description>
   </item>
   <item>
      <title>ZX81 Question?</title>
      <link>https://worldofspectrum.org/forums/discussion/21204/zx81-question</link>
      <pubDate>Fri, 27 Jun 2008 00:06:08 +0000</pubDate>
      <dc:creator>Mark Wills</dc:creator>
      <guid isPermaLink="false">21204@/forums/discussions</guid>
      <description><![CDATA[Just bought a ZX81 on Ebay (as you do). It was sold as not working, but once I'd changed the fuse in the plug on the transformer it was working like a good un.<br />
<br />
I opened the machine up (the first time it's been opened, judging by the four rubber feet on the bottom) to see what was in there.<br />
<br />
I was very surprised it's a 1980 issue board, and the processor has a 'bodge board' on it, looks like it was soldered in at the factory.<br />
<br />
Its a board with legs on the bottom which are soldered directly onto the legs of the Z80, and it has two 74LS chips on it. What does this little board do?<br />
<br />
(The machine has been running for 5 hours now with not a hint of trouble! Delighted with it!)<br />
<br />
I'm off to read my ZX81 Basic book now!<br />
<br />
Mark]]></description>
   </item>
   <item>
      <title>Erratum in Spectrum schematics?</title>
      <link>https://worldofspectrum.org/forums/discussion/21212/erratum-in-spectrum-schematics</link>
      <pubDate>Fri, 27 Jun 2008 18:47:02 +0000</pubDate>
      <dc:creator>mcleod_ideafix</dc:creator>
      <guid isPermaLink="false">21212@/forums/discussions</guid>
      <description><![CDATA[Forgive me if this is old news, but I have recently adquired some new microspeakers for repairing damaged ones in various Spectrums. One of these had TR7 missing. When I was to check pin locations (emitter, collector, etc.) I discovered that collector of TR7 is not tied to +5V as stated on the schematic, but to +9V. It seems that all Spectrum schematics from issue 3 to issue 5 have the same mistake. Issue 6A (which seems to be drawn in a different manner than the previous ones) is not affected.<br />
<br />
For details about the microspeaker replacement, I invite all you to check it out on my web page.<br />
<br />
Thanks!]]></description>
   </item>
   <item>
      <title>PS/2 mouse interface (AMX compatible?)</title>
      <link>https://worldofspectrum.org/forums/discussion/21202/ps-2-mouse-interface-amx-compatible</link>
      <pubDate>Thu, 26 Jun 2008 21:53:03 +0000</pubDate>
      <dc:creator>Hideki</dc:creator>
      <guid isPermaLink="false">21202@/forums/discussions</guid>
      <description><![CDATA[Hihi<br />
<br />
Not sure if this has been done before, but I'm pondering an interface allowing you to use a modern PS/2 mouse with the spectrum, probably using a PIC microcontroller to do most of the donkey work<br />
<br />
Anyone know how the mouse is read? (Ports etc.)<br />
<br />
Also, has it been done before, if so I don't want to duplicate a solution that already exists...<br />
<br />
Thanks ^^]]></description>
   </item>
   <item>
      <title>RAM paging and port usage</title>
      <link>https://worldofspectrum.org/forums/discussion/21194/ram-paging-and-port-usage</link>
      <pubDate>Thu, 26 Jun 2008 05:11:59 +0000</pubDate>
      <dc:creator>clausjahn</dc:creator>
      <guid isPermaLink="false">21194@/forums/discussions</guid>
      <description><![CDATA[Dear users and developers,<br />
<br />
I'm just trying to find some detail information about RAM paging on the Spectrum 128 and later models, especially those about the Russian clones Scorpion 256k, Pentagon 512k and Pentagon 1024k. I hope, someone who knows the details much better could check/correct my below data.<br />
<br />
By digging out several FAQs and technical documentations here's what I found:<br />
<br />
Spectrum 128k and +2:<br />
port 7ffd bits 0..2 select one of 8 RAM pages, which is paged at C000..FFFF.<br />
page 5 is always paged at 4000..7FFF, page 2 always at 8000..BFFF. One of the ROM is paged at 0000..3FFF.<br />
<br />
Spectrum +2A and +3:<br />
if port 1ffd bit 0 is reset, same as Spectrum 128k and +2.<br />
if port 1ffd bit 0 is set, we have 4 different RAM pagings depending on the bits 1 and 2 of port 1ffd, which is called "special mode". Using the special mode, no ROM is paged at 0000..3FFF.<br />
<br />
Spectrum 48k, Timex TC2048, TC2068, TS2068<br />
No RAM paging, but always fixed 48k RAM starting at address 4000h.<br />
<br />
Spectrum +3E:<br />
????<br />
<br />
Scorpion ZS 256k:<br />
if port 1ffd bit 4 is reset, one of the first 8 RAM pages (RAM 0..RAM 7) is paged at address C000..FFFF, page 5 is always paged at 4000..7FFF, page 2 is always paged at 8000..BFFF.<br />
if port 1ffd bit 4 is set, one of the second 8 RAM pages (RAM 8..RAM 15) is paged at address C000..FFFF. Others same as above.<br />
<br />
Pentagon 128k:<br />
same as Spectrum 128k and +2<br />
<br />
Pentagon 512k:<br />
In addition to the paging methods of the Spectrum 128k, bits 6 and 7 of port 7ffd are also used to select the RAM bank for paging at address C000..FFFF.<br />
Now, the things become unclear. How exactly are the bits 0..2 and 6..7 used for selecting one of the 32 RAM pages of the Pentagon 512?<br />
Is it just a 5-bit integer with bits 7:6:2:1:0 that contains the number of the selected RAM page (0..31)?<br />
<br />
Pentagon 1024k:<br />
Same as Pentagon 512k, but as we have 64 RAM pages now, we need an additional bit. bits 5,6 and 7 are now used in addition to the bits 0..2 of port 7ffd. My proposal would be a 6-bit integer with bits 7:6:5:2:1:0 that contains the number of the selected RAM page (0..63)?<br />
<br />
Hopefully, somebody could help me...<br />
<br />
Kind regards,<br />
<br />
Claus]]></description>
   </item>
   <item>
      <title>connecting 3" flopy disk drive to PC</title>
      <link>https://worldofspectrum.org/forums/discussion/20714/connecting-3-flopy-disk-drive-to-pc</link>
      <pubDate>Tue, 20 May 2008 10:49:39 +0000</pubDate>
      <dc:creator>orange</dc:creator>
      <guid isPermaLink="false">20714@/forums/discussions</guid>
      <description><![CDATA[looking at this image:<br />
<img src="http://www.fileden.com/files/2006/9/12/214909/Amiga/3inchFDD_figure.png" alt="3inchFDD_figure.png" /><br />
<br />
why are pins 2,4,6 and 14 coneccted to +5V?<br />
those signals are:<br />
<br />
2  Density Select<br />
4  Reserved<br />
6  Reserved<br />
14 Drive Sel A (might be pin 12,drive select B, after swap)<br />
<br />
and direction for all is FROM computer to drive. so they should be irrelevant, shouldn't they? if not, where do I connect them, to +5V molex?<br />
<br />
BTW, is it really safe to connect 'motor_enable' and 'drive_select' together?]]></description>
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   <item>
      <title>Is it possible to use external power supply for +-12; +-5 for ZX Spectrum</title>
      <link>https://worldofspectrum.org/forums/discussion/21098/is-it-possible-to-use-external-power-supply-for-12-5-for-zx-spectrum</link>
      <pubDate>Thu, 19 Jun 2008 06:34:07 +0000</pubDate>
      <dc:creator>65C02</dc:creator>
      <guid isPermaLink="false">21098@/forums/discussions</guid>
      <description><![CDATA[Recently I acquired a damaged Sinclair ZX Spectrum, issue 3B.<br />
According to the maintenance manual I have to replace TR4 and TR5.<br />
These type of transistors (neither the substitutes, that are listed in some topics of this forum) does not seem findable, so I'll probably try using BD237 and 2N2905A.<br />
As far as I understood, these transistors are for creating +12V and -12V. So probably I can use a regular PC power supply for the Sinclair and discard the power supply parts. Has anyone done it and should I know something special?<br />
<br />
Also, I wonder, because ZTX650 is for 2A, and some of the substitutes listed are for smaller current (i.e. BC489 for 0,5A) would 0,5 be enough? Somebody has repaired the spectrum before I acquired it, and now it is with a 2N2907 intead of ZTX213 and with a BC337-40 (Ic=0,5A) instead of ZTX650.<br />
I have no idea it worked after being repaired (obviously two 4116 have been replaced), but since it is broken again, probably 0,5A instead of 2A is a bad idea?]]></description>
   </item>
   <item>
      <title>Interface III...Cannot load saved file. Any ideas ?</title>
      <link>https://worldofspectrum.org/forums/discussion/21133/interface-iii-cannot-load-saved-file-any-ideas</link>
      <pubDate>Sat, 21 Jun 2008 15:07:44 +0000</pubDate>
      <dc:creator>Pilsener</dc:creator>
      <guid isPermaLink="false">21133@/forums/discussions</guid>
      <description><![CDATA[I got hold of an Interface III (see <a href="ftp://ftp.worldofspectrum.org/pub/sinclair/hardware-pics/InterfaceIII.jpg" rel="nofollow">THIS</a> pic).<br />
This box makes an image, with it's own header menu, which then is saved to tape.<br />
<br />
The problem is: The programs I save to tape from this box won't load back into the Speccy past the initial seconds where the red/blue stripes is showing in the border.<br />
<br />
The initial seconds shows either "Bytes: SCREEN$" or "Program: ???????"<br />
<br />
Here's what I have tried to make it load:<br />
Loading/saving the prog from both tape and PC (several programs tried).<br />
The signal to the Speccy has been fed through different amplifiers with various levels.<br />
Equalizers has been used. Both those EQ's in the playback programs on the PC, as well as exteral EQ's.<br />
All kinds of EQ-settings have been tried during the 3 hours spent with this before I gave up.<br />
<br />
Now I need some ideas.  Can it be a fault with the interface ?<br />
Please anyone ?]]></description>
   </item>
   <item>
      <title>RZX Player interface - Possible?</title>
      <link>https://worldofspectrum.org/forums/discussion/21106/rzx-player-interface-possible</link>
      <pubDate>Fri, 20 Jun 2008 07:07:07 +0000</pubDate>
      <dc:creator>zxbruno</dc:creator>
      <guid isPermaLink="false">21106@/forums/discussions</guid>
      <description><![CDATA[If I have a Mass Storage interface and some media (CF, SD) with a couple RZX files, what would I need to play them on a real Spectrum? If the RZX file is simply a long list of recorded keys, can't we use that interface or an extra one to make the Spectrum 'think' that those keys are being pressed? If this can be done it could be really useful for those who take their Spectrums to compos, meetings, etc.<br />
<br />
Imagine a Spectrum showing what seems to be a very long clip of several games being shown in attract mode, tutorials showing how to use trackers or drawing software, etc. but without wasting memory! A Speccy playing a long 'video' file without the need for megabytes!]]></description>
   </item>
   <item>
      <title>new HARDWARE for ZX - tested</title>
      <link>https://worldofspectrum.org/forums/discussion/21143/new-hardware-for-zx-tested</link>
      <pubDate>Sun, 22 Jun 2008 10:38:57 +0000</pubDate>
      <dc:creator>velesoft</dc:creator>
      <guid isPermaLink="false">21143@/forums/discussions</guid>
      <description><![CDATA[<a href="http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fcf_to_ide.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en" rel="nofollow">http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fcf_to_ide.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en</a><br />
<br />
<a href="http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fsd_to_ide.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en" rel="nofollow">http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fsd_to_ide.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en</a><br />
<br />
<a href="http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Faudio_cassette.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en" rel="nofollow">http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Faudio_cassette.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en</a><br />
<br />
<a href="http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fmp3_cassette.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en" rel="nofollow">http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fmp3_cassette.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en</a><br />
<br />
<a href="http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fbluetooth_cassette.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en" rel="nofollow">http://translate.google.com/translate?u=http%3A%2F%2Fvelesoft.speccy.cz%2Fzx%2Fbluetooth_cassette.htm&amp;hl=cs&amp;ie=UTF8&amp;sl=cs&amp;tl=en</a><br />
<br />
VELESOFT]]></description>
   </item>
   <item>
      <title>Reproducing the Multiface 3 - possible within reasonability ?</title>
      <link>https://worldofspectrum.org/forums/discussion/21004/reproducing-the-multiface-3-possible-within-reasonability</link>
      <pubDate>Fri, 13 Jun 2008 02:32:55 +0000</pubDate>
      <dc:creator>Pilsener</dc:creator>
      <guid isPermaLink="false">21004@/forums/discussions</guid>
      <description><![CDATA[Has anyone of you ever done that ?]]></description>
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