MB02 Technical Documentation - ZX Spectrum, Retro Computing

	Everything about the MB02

	*What's new?* March 6 2009 I decided to make òne page dedicated to the MB02, containing all tehnical 'must-knows' and to be a collection area of technical knowledge. I will of course get some people complaining about why there should be another website for this, because there already is the WoS Forum where many technical topics are discussed. But a discussion always results in just a few important pieces of information everyone have to filter out for themselves. I hate doing things twice, and I know others also do.. March 7 2009, March 8, March 9, March 10, March 12 Added info I received by mail. Will be doing more of that the next days and weeks (about 400 emails to process...).

	*What is the MB02(+IDE) and what can it do?* Original design and manufacturer The MB02 was originally designed and manufactured by the 8BC (Eight Bit Company): http://www.8bc.com/sinclair/ The MB02 is an interface for the ZX Spectrum (all models) that combines the following features: - HD (High Density) floppy interface with 1.8 MByte capacity on each floppy, and speeds up to 50K/sec. - A large eprom where you mechanically can select the rom to use - 128 to 512KB Sram where system software is stored in or which you can use for software - A Z80DMA controller, needed for floppy-actions, but also can be used for software - An RTC clock The 8BC sold the MB02 till about 2002 (maybe earlier), as Thomas Erbele explained to me once: "The MB02 is out of sale now for over 1 year", that was in 2003. How to control the 128K - 512K sram Have to sort this out [To me, it would be best to bring in the new MB04+ for example the external memory bank (nor RAM memory, neither ROM). Paging SRAM 512kB banks is fine but I need to clip the 16k bank outside the space 0-65535. This would make programing and contolling over the system procedures much easier. (From this "external" memory you can also trace the programs running in ROM space which is on MB02+ impossible and it is practically impossible on every disk system ever made on speccy) ] MBIDE With the MBIDE(/2/3) addon you can attach an IDE harddrive or Compact Flash card as mass storage. The MB02+IDE Ingo Truppel is de designer of the MB02+IDE: [website is recently gone down because Ingo has a new internet-provider] This interface is a complete rebuild of the MB02 on a much smaller (4-layer) PCB, and includes an IDE interface already, along with 512KB sram. Pictures Click here here for a picture gallery. Please report your additions to this section to me by the contact form!

	*Facts of the MB02(+IDE)* Known compatibilities - ZX Spectrum 48K, 128K (heatsink model),+2 (grey model), +2A, +2B, +3 - depending on the model you have to set some jumpers - Internal Proface - I bought an eBay auction with MB02 and also an internal Proface, and that combi works, even with KMT - Kempston Mouse Turbo - but the combination with a 128K heatsink model does not seem to work properly with, it does work with +2 (heatsink)
	The Kempston Mouse Turbo:

	Known incompatibilities - PC Keyboard Interface (unmodified) - March 2009: we are trying to find a solution for this - see Problems and Solutions underneath (Ben Versteeg)
	The PC Keyboard Interface:
	Z80DMA Ben: Is it possible to move the Z80DMA to the ZX Spectrum, so that could solve problems caused by the distance between Spectrum and MB02? Like Datagear (http://velesoft.speccy.cz/data-gear.htm)? Ingo: DataGear does not care about floppy disk interrupt - so floppy data transfer would be disabled. Ben: The original Z80DMA chip is a RFT-DMA U858D. There are several brands that made Z80DMA chips, like Zilog itself, or Mostek (I found Mostek Z80DMA's on eBay: http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=290142307443). Is it possible another brand could create better signals or handle worse signals? Ingo: You will not find a better one. If you replace it with the Zilog one or any other clone know that writing to disk will not work. The reason is, that there is a bug in BS-DOS. Zilog recommends a special order of initializing statements for the DMA. The authors of BS-DOS did not care about this and therefore writing to disk (or any other IO-device) via DMA does not work. The RFT clone UA858D has advanced properties and doesn't care about errors in the initiatizing order. I had a lot of difficuilties to get these chips - so be happy to have it. (I have some stored for repair and in eastern Germany it is possible to get more. Can the MB02 do without floppydrive? Thomas from Sintech sais: "This is absolutely impossible. The MB02 needs a boot disk first to install HDD-system. Even when this system is in memory, it sometimes can go corrupt and has to be booted again. Floppy interface is needed. On the other side I would like a floppy interface for the reason, that you can be independent from PC. People who like only CF-card can buy DIVIDE-Interface and not MB04." After I started using the MB02+IDE this is my opinion also; there are enough reasons the sram data get's corrupt and you'll need to install the system again. There is one solution though: if it's possible to boot from HDD instead of floppy, there is no need of a floppydrive to reïnstall the system again. Now there is such a rom-upgrade, but it only works with FATware; read about it somewhere else on this site. NMI menu and updates A czech developer who calls himself 'Hood' developed the NMI menu. Here's a list of NMI menu updates: http://hood.speccy.cz/dwnld/135inf.htm You can download them here: http://hood.speccy.cz/ At Hood's website you can react to updates, and maybe add some proposals for the next version: http://hood.speccy.cz/ The Ground-connection between Spectrum and MB02 From Ingo: It is VERY important to have a stable GND connection between MB02+ and Speccy even with interfaces between both devices. Use an additional short and big wire to connect the Ground of both devices if possible. The reason for this is: If the Ground-wiring of one of the devices (Spectrum or MB02) fails, the complete current of both devices (about 1.4 Amperes) will flow through the edge connector, that is certainly not made to cope with such current. There is a very large change that electronic parts will be damaged then. MB02 related websites - http://tcg.speccy.cz/ - MB Commander and more MB02 related forums There is an active community which mostly communicates on the World of Spectrum forums: - Ingo's first thread about the MB02+IDE - Ingo's second thread about the MB02+IDE - About Multitech - About MB02 emulation - Questions about converting TZX to MB02 - Anestis' thread about problems with his MB02+ (old) - A list of MB02 users (old) 512K Sram upgrade To upgrade an MB02 from 128K sram to 512K, Jan Kucera from the 8BC once sent me an email with this small schematic: I've seen this is also already reported on the 8BC website in the MB Documentation II document found in the Download area. Please report your additions to this section to me by the contact form!

	Recent (unfinished) developments Whenever something that is described here gets a certain 'final' status, it will be moved to the 'Facts'-category. Fatware BTW: There is fatware available for MB02+. So divIDE function is available at MB02+IDE also. What the MB02 really needs From Milan Stava (back in 2006): "My opinion is, that what MB02+ needs is SOFTWARE, a new BSDOS first, then it would need utilities. The otherwise powerfull hardware on MB02+ is purely used with obsolete and only a few good software." Please report your additions to this section to me by the contact form!

	Problems and solutions Distance between Spectrum and MB02(+IDE) Ingo: One big problem of using a longer cable between speccy and MB02+IDE is indeed the clock line ESPECIALLY USING a 128k heatsink! This computer has a very bad circuit to make the CPU clock. The gray +2 is much better in that direction. Ben: I'm curious if moving the Z80DMA to the Spectrum would solve some problems. PC Keyboard Interface incompatibility Ben: As you may have read during 2008 and 2009 on my weblog, Miguel from Spain and I created a new interface to connect an average PC keyboard to your Spectrum. But Anestis from Greece and myself have had a lot of trouble getting the interface to work with the MB02+IDE. The system seems stable at first, but then sometimes datacorruption is caused, and the system has to be loaded from the install-floppy again. Ben: Still (at march 2009) we have no descent solution to this problem. I did some modifications on the PC keyboard interface so that it's load on several signals is not that high, but even with those changes a setup with MB02 is not always stable. Now it seems it's not entirely the PCKI itself causing all the trouble, but even the MB02 with only an edge-extender (like the Currah u-slot) gives instability. So the main problem seems to be the discance between Spectrum and MB02, which you can read about above. I still think if we find a solution for the distance-problem, the PCKI will work flawlessly.. Bad Clock-signal on ZX Spectrum 128K (heatsink model) Ingo: You can try to improve its behaviour by placing an additional resistor from the clock line to +5V. Ben: Working on this (March 2009)! There already is a 180 Ohm resistor according to the schematic, have to ask Ingo about that. Isn't the clock signal being made more robust on the MB02 already? Please report your additions to this section to me by the contact form!

	*About this website* It's created and being kept up-to-date by Ben Versteeg. Click here for my Sinclair-related weblog. Use the contact form to send me an email please, that keeps spam away.