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Commodore Free 14
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Commodore_Free_Issue_14_2007_Commodore_Computer_Club.d64
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t.iv laszlo
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2023-02-26
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Interview with Jozsef Laszlo
DTV mod: C64 DTV in original C64 case
Q - Please introduce yourself to our
readers!
A - I am Jozsef Laszlo, an IT engineer
originally from Hungary but now I live
in Canada. I am 37 years old so I grew
up in the time when the Commodore 64 &
ZX Spectrum were "the" computers. I
work for a video game producer company
as a game programmer.
Q - What interested you in C= machines
or do you just like the C64 DTV?
A - I like all the old machines. In
fact, I collect them. I have lots of
old 8bits machines at home, most of the
C= ones (16/64/128) & ZX Spectrums as
well. When I first read about the DTV &
it's success, I was happy because it
means, I am not the only one who is in
love with old stuff. Obviously I wanted
one. Actually when I saw how cheap it
was, I bought two. One is still in the
original joystick case, but the other
one is in a C64 case.
Q - Someone must be reading thinking
what is a C64 DTV can you introduce &
describe the device?
A - It's a C64 (mostly) compatible
device which originally was designed
for a small TV game with 30 built-in
games. Thanks to hacking capabilities
it's much more than that. I'd call the
DTV a new C64 with advanced graphics
modes, more memory & more features.
You can turn the DTV into a classic C64
where you can expand your BASIC,
overwrite your KERNAL, speed up your
applications, etc. The DTV is a must
for all C64 lovers.
Q - Quite a few sites are devoted to
hacking the DTV were these useful or
did you create your own procedure for
Hacking the Device?
A - Yes, they were absolutely useful.
Before you start hacking a device, you
have to know it. Fortunately, these
sites can help discover the device both
from software & hardware point of view.
I had to download all the documents &
schematics before I started my own
hack.
Q - The device was designed with
Hacking in mind is this correct?
A - Sure. The original device was
designed by the same American lady
called Jeri Ellsworth who designed the
Commodore One as well. She did a
marvellous job. I am pretty sure that
she wanted "us" to hack the device.
That's why you can find user port,
keyboard & IEC connectors on the PCB.
Thanks, Jeri.
Q - I have seen a few DTV devices in
various cases, what prompted the
decapitation of a real C64 to house the
device?
A - I needed a DTV which is really
close to the original C64. In normal
hacks people use PS2 keyboards &
connectors patched to the joystick
case. For me it's just does not look
like a computer. It deserves more. It
deserves the original case. (Just my
point though.) Besides, isn't it nice
to see a C64 which is much more than a
C64?
Q - Do you have electronics Experience?
A - Yes I do. Originally I graduated as
an Engineer of Automation & Industry
Informatics which means both h/w & s/w
experience. Earlier I worked with
discrete IC's (74HC series)but now I'm
rather interested in FPGA's. I have
some Xilinx developer boards. I
designed a ZX Spectrum.
Q - Did using the original C= Keyboard
cause problems?
A - Some. The original design itself is
quite strange. The keyboard membranes
have some resistances (65-75 ohm), but
there are no protectng diodes on the
CIA lines, therefore it's possible to
make a short circuit if one row drives
Vcc while the other does Gnd & you
press 2 keys in the same column. There-
fore I needed a special row selection
method in the software. Instead of
rolling a single 0 bit (which means
GND) through the rows I turn on the
output for one row only. That means
there is now logical 1 on all other
rows. This is a hardware issue. Another
annoying problem is the PS2 mapping
inside the DTV. The DTV's keyboard
interface is a PC keyboard interface.
On the PC keyboard certain symbols are
not where they supposed to be. For
example the keyboard 2 has the sign @
on the PC, while on the C64 it has the
" sign. Therefore the microcontroller
has to do some cheating & re-remapping
some keys. For a perfect solution we'd
need a more complex software for the
microcontroller. It's not perfect now.
Q - Do you have any tips or better ways
of working while doing the hack you
would like to pass on to readers?
A - Be careful! If you are not
experienced in soldering & electronics,
ask someone who is. The DTV pcb is
quite small, soldering is really
tricky. You need thin wires & patience.
And before you put your DTV into the
case, plan the layout! Check if all the
connectors, holes are gonna fit. You
don't have to copy my solution. Try to
plan a better one!
Q - The DTV is quite a small circuit
board inside a large C= Case do you
plan to add further hardware?
A - I will be soldering the joy ports
as well so there will be a way to use
original joysticks. I also plan to
redesign the entire disk interface,
because I want to free the IEC bus for
external devices. I'd like to use a
fast communication line between the DTV
& the microcontroller for disk
operations. I never liked the IEC
speed. It's just too slow. This means
I'll have to modify the basic & kernal
as well. I'd like to see dos or unix-
like commands so I can type DIR or CD
or MKDIR.
Q - Did you experience any major
problems in the process?
A -As I mentioned above, the keyboard
remapping, changing codes on the fly &
sending virtual shifts were
problematic. On the hardware side, you
have to be very careful with the
AtMega's fuse bits. These are the
configuration bits for the clock source
or additional interfaces like SPI or
JTAG. If you play with your fusebits,
you can kick out your microcontroller
easily. Don't do that. Ask experienced
people!
Q - Do you still use C= machines?
A -Rarely but yes, I do. It's just so
much fun.
Q - Has the device been taken too
kindly by readers of the website?
A -I think people like it. Of course,
tastes are different so I can imagine
that some found it silly to put back
the DTV in the C64 case. Doesnt matter,
does it? I am pretty sure that hard-
core PC gamers (the new guys) think
that old guys (we) are silly. I don't
really mind. I am old enough to do what
I really like. :-)
Q - Has anyone criticized you for
decapitating a C64?
A -I havent had any criticism so far.
Some mentioned bugs. Thanks for that!
Q - Do you plan any other DTV
conversions into other cases?
A - I want to finish this one first,
then we'll see. I really don't know
yet. I'd like to go ahead with my FPG
A project (ZX Spectrum) as well.
Q - Do you feel there are any
limitations or problems with the DTV?
A -Well, it's obviously not 100%
compatible with the original C64,
therefore some games won't RUN. Thanks
to some great guys, more & more old
games are patched to work with DTV. So
I'd say compatibility issues are
annoying, but the advantages of the DTV
eliminate them. What I really want to
see is a new game which is specially
written for the DTV & uses it's
capacities.
Q - Our readers I know will be wanting
to carry out the same process do you
have a step by step process for the
non-technical that can maybe solder OK?
A -Sorry, not really. I truly think
that inexperienced people should ask
someone who did thinks like this
before. You guys don't want to ruin
your DTV, do you?
Q - Do you have any soldering tips for
the non-soldering readers?
A -See pervious answer. However, this
is a profession that can be learnt. Ask
someone to do it, then learn. That's
what I did.
Q - Do you have anything to add or
question you wished i had asked?
A -I'd rather just say something to
your readers. Keep what you have, don't
let the 8bits age disappear. Although
it's history now, as long as we are
here, 8bits machines won't die.