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) ]
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
Ingo: DataGear does not care about floppy disk interrupt - so floppy
data transfer would be disabled.
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
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.
the MB02 do without floppydrive?
Thomas from Sintech sais: "This
is absolutely impossible. The MB02 needs a boot disk first to install
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.
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/
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
Use an additional short and big wire to connect the Ground of both devices
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.
- MB Commander and more
There is an active community which mostly communicates
on the World of Spectrum forums:
first thread about the MB02+IDE
second thread about the MB02+IDE
about converting TZX to MB02
thread about problems with his MB02+ (old)
list of MB02 users (old)
To upgrade an MB02 from 128K sram to 512K, Jan Kucera
from the 8BC once sent me an email with this small schematic:
seen this is also already reported on the 8BC
website in the MB Documentation II document found in the Download
between Spectrum and MB02(+IDE)
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.
curious if moving the Z80DMA to the Spectrum would solve some problems.
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.
(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)
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..
Clock-signal on ZX Spectrum 128K (heatsink model)
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?