Everything about the MB02



The MB02 is the most advanced mass storage interface for the ZX Spectrum - ever!

It combines these awesome features:
- High Density floppy interface with 1.8 MByte capacity on each floppy, and speeds up to 50K/sec!
- A Z80DMA controller!
- 128 to 512KB Sram where system software is stored in or which you can use for software
- A Real Time Clock chip
- Additional IDE interface for superb mass storage functions!

The MB02 was originally designed and manufactured by the 8BC (Eight Bit Company): http://www.8bc.com/sinclair/

Ingo Truppel (Truppel Online) still produces the original MB02 and the MB02+IDE.
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.

Contact me of you need to get in contact with Ingo for an MB02!

Click here here for an MB02 picture gallery.

- ZX Spectrum 48K, 128K (heatsink model),+2 (grey model), +2A, +2B, +3 - depending on the model you have to set some jumpers
- Kempston Mouse Turbo

- Internal Proface


Knowledge base

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) ]

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.

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?



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