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Magic Desk Cartridge Question?
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ramswell
Nov 11, 2011, 11:25:27 PM11/11/11
to
I finally got around to desoldering the prom from the board and
replacing it with the 28-Pin Socket and retried the program and it
worked FLAWLESSLY! ;( (THANK GOD!)
So my question is this: I have a 512KB EPROM on hand and I "WOULD
LIKE" to utilize it with the cartridge in the form of a "MENU DRIVEN
BASE" of some form.
Something like this....... When you insert the cart and power up the
C= the menu will automatically load up showing the conbtents of the
other programs that are on the cartridge. Then by selecting (Oh I
dunno..... up/down--- F1/F3 whatever combination you can think of)
you can select the program that resides in that particular portion of
memory on the eprom and RUN IT DIRECTLY FROM THE CART THROUGH THE
MENU!
Is that possible with the Magic Desk or would I HAVE TO purchase the
64 NIC+? I do plan on purchasing it in the near future anyways, but
as of now I'm just asking "WHAT IF's." ;)
Any responses to this would be greatly appreciated.
Have a great weekend!
Charles>8-Bit Designs
Clocky
Nov 12, 2011, 12:43:42 AM11/12/11
to
"ramswell" <shifty...@hotmail.com> wrote in message
news:d8ae7504-6dcb-4889...@k38g2000pro.googlegroups.com...
For a start the magic desk cartridge isn't wired to use a 512k EPROM. It
takes more than just a 28 pin socket to make that happen, the board would
need some extensive hacking as it wired to use 4x2764 EPROMs and the
additional lines required are tied high and that would have to be sorted
before you soldered in the sockets but...
Then your problem is that the glue logic controlling the bank selection
would also need to be hacked, all the ROMs removed and the whole lot rewired
to the single 512k EPROM. But that would still only give you max 32K or so
(without analysing the schematic but that would be my guess) as that is all
that the bank selection logic can control as it is.
Then you would have to write the sofware that controls the bank selection
and put that in one of the banks. Dunno how handy you are at assembler...
Well, it could be done I suppose, but... would you really want to given
that's not exectly a simple project? I thought the 64NIC+ also uses a
hardware switch to allow you to select which program (bank) you want to
select, and is not menu driven?
Have a look here, if you understand this you might get some idea (a hacking
project I did a while ago now with the Magic Desk cart).
http://users.on.net/~clockmeister/other/EPROM-Cartridge/Magic-Desk-4x8k-mod/
You would need to do plenty more.
ramswell
Nov 12, 2011, 3:13:42 PM11/12/11
to
On Nov 11, 9:43 pm, "Clocky" <notg...@happen.com> wrote:
> "ramswell" <shifty_bu...@hotmail.com> wrote in message
> http://users.on.net/~clockmeister/other/EPROM-Cartridge/Magic-Desk-4x...
>
> You would need to do plenty more.- Hide quoted text -
>
> - Show quoted text -
DUDE! THAT'S "AWESOME!" :) Your WAY BETTER than I am at that kind
of stuff (obviously) as I never would of thought in a million years
that I would need to TOTALLY clean out the ENTIRE BOARD and install
all that stuff on it in order to get it to do anything other than the
designed functions.
So those eproms that you installed are ALL 2764's? Also, the switch
that you installed there; does that switch banks between the four
eproms?
This is something that I might still be interested in doing in the
future sometime, but my interest is in the "LARGER" eproms due to what
my desire to accomplish is.
What I would "LIKE" to do is get it to where it "RUNS GEOS" on it
from the cartridge! I know that's asking QUITE A LOT, but that is what
I want to do. Also, I would like to get the banks to switch between
games and utilities so I can put Montazuma's Revenge, Mighty Bomb Jack
and Mr. Do on the games section and put Omega-Q 2, GEOS, and Novaterm
9.6 on the Utilities section.
So you can see why I was asking if this was either at all "possible,"
or if it's even something I even want to bother myself with even doing
at all (like you said <the labor, time, effort and all and STILL NOT
GETTING WHAT I WANT out of it>). :(:(
So I guess I will go ahead and "REMOVE EVERYTHING" and try and get a
hold of a few 2764 eproms and install them onto the board and go from
there by following your diagram and instructions and see what I can do
at that point.
This is VERY INFORMATIVE and GREATLY APPRECIATED!
Thanks a lot! ;)
Charles
> "ramswell" <shifty_bu...@hotmail.com> wrote in message
>
> You would need to do plenty more.- Hide quoted text -
>
> - Show quoted text -
DUDE! THAT'S "AWESOME!" :) Your WAY BETTER than I am at that kind
of stuff (obviously) as I never would of thought in a million years
that I would need to TOTALLY clean out the ENTIRE BOARD and install
all that stuff on it in order to get it to do anything other than the
designed functions.
So those eproms that you installed are ALL 2764's? Also, the switch
that you installed there; does that switch banks between the four
eproms?
This is something that I might still be interested in doing in the
future sometime, but my interest is in the "LARGER" eproms due to what
my desire to accomplish is.
What I would "LIKE" to do is get it to where it "RUNS GEOS" on it
from the cartridge! I know that's asking QUITE A LOT, but that is what
I want to do. Also, I would like to get the banks to switch between
games and utilities so I can put Montazuma's Revenge, Mighty Bomb Jack
and Mr. Do on the games section and put Omega-Q 2, GEOS, and Novaterm
9.6 on the Utilities section.
So you can see why I was asking if this was either at all "possible,"
or if it's even something I even want to bother myself with even doing
at all (like you said <the labor, time, effort and all and STILL NOT
GETTING WHAT I WANT out of it>). :(:(
So I guess I will go ahead and "REMOVE EVERYTHING" and try and get a
hold of a few 2764 eproms and install them onto the board and go from
there by following your diagram and instructions and see what I can do
at that point.
This is VERY INFORMATIVE and GREATLY APPRECIATED!
Thanks a lot! ;)
Charles
Ruud
Nov 12, 2011, 3:30:26 PM11/12/11
to
Hallo Clocky,
> http://users.on.net/~clockmeister/other/EPROM-Cartridge/Magic-Desk-4x...
I can be completely wrong but I think there is an error in your
schematic. You connect the dipswitches to pin 4, 5, 6 and 7 of the
former 74LS138. But 4, 5 and 6 are inputs of the 138 and therefor
cannot select the (EP)ROMs. I would have expected the dipswitches to
be connected to 7, 9, 10 and 11 and that is also what the photos show
(more or less) IMHO.
But seeing the photos my first question was: why did you want to
replace the 138 with switches? And if you wanted switches, why didn't
you connect them to the 138; you then only needed two and wouldn't run
the risk of selecting two or more at the time.
The 74LS175 is a 4-bits latch and let's assume that these bits have
been connected to the data bus. IMHO two of the bits are used to
select the (EP)ROMs. Which leaves us with two free bits: these can be
used to control two extra address lines which enable you to use 27256s
instead of 2764s. Piggyback an extra 175 on top of the original one
and you can use 27512s and still have three free bits for ..... (just
use you imagination :).
Groetjes, Ruud Baltissen
http://www.Baltissen.org
> http://users.on.net/~clockmeister/other/EPROM-Cartridge/Magic-Desk-4x...
I can be completely wrong but I think there is an error in your
schematic. You connect the dipswitches to pin 4, 5, 6 and 7 of the
former 74LS138. But 4, 5 and 6 are inputs of the 138 and therefor
cannot select the (EP)ROMs. I would have expected the dipswitches to
be connected to 7, 9, 10 and 11 and that is also what the photos show
(more or less) IMHO.
But seeing the photos my first question was: why did you want to
replace the 138 with switches? And if you wanted switches, why didn't
you connect them to the 138; you then only needed two and wouldn't run
the risk of selecting two or more at the time.
The 74LS175 is a 4-bits latch and let's assume that these bits have
been connected to the data bus. IMHO two of the bits are used to
select the (EP)ROMs. Which leaves us with two free bits: these can be
used to control two extra address lines which enable you to use 27256s
instead of 2764s. Piggyback an extra 175 on top of the original one
and you can use 27512s and still have three free bits for ..... (just
use you imagination :).
Groetjes, Ruud Baltissen
http://www.Baltissen.org
ramswell
Nov 12, 2011, 3:48:05 PM11/12/11
to
showing me how I could do this? As I DO DESIRE to run the 512 rather
than having to go out and get all this stuff I don't have on hand
right now.
Thanks Ruud!
Charles
ramswell
Nov 12, 2011, 4:38:26 PM11/12/11
to
On Nov 12, 12:30 pm, Ruud <ruud.baltis...@gmail.com> wrote:
I downloaded lots of it for "future" projects! ;)
Know where I may be able to get my hands on a 1541 PCB board? I want
to "try" that IDE 41 project out.
Thanks again and have a great weekend!
Charles
Clocky
Nov 12, 2011, 6:30:07 PM11/12/11
to
Ruud wrote:
> Hallo Clocky,
>
>
>> http://users.on.net/~clockmeister/other/EPROM-Cartridge/Magic-Desk-4x...
>
> I can be completely wrong but I think there is an error in your
> schematic. You connect the dipswitches to pin 4, 5, 6 and 7 of the
> former 74LS138. But 4, 5 and 6 are inputs of the 138 and therefor
> cannot select the (EP)ROMs. I would have expected the dipswitches to
> be connected to 7, 9, 10 and 11 and that is also what the photos show
> (more or less) IMHO.
>
It's 74LS139 4,5,6,7 are data outputs that go to the EPROM select lines.
> Hallo Clocky,
>
>
>> http://users.on.net/~clockmeister/other/EPROM-Cartridge/Magic-Desk-4x...
>
> I can be completely wrong but I think there is an error in your
> schematic. You connect the dipswitches to pin 4, 5, 6 and 7 of the
> former 74LS138. But 4, 5 and 6 are inputs of the 138 and therefor
> cannot select the (EP)ROMs. I would have expected the dipswitches to
> be connected to 7, 9, 10 and 11 and that is also what the photos show
> (more or less) IMHO.
>
> But seeing the photos my first question was: why did you want to
> replace the 138 with switches? And if you wanted switches, why didn't
> you connect them to the 138; you then only needed two and wouldn't run
> the risk of selecting two or more at the time.
>
> The 74LS175 is a 4-bits latch and let's assume that these bits have
> been connected to the data bus. IMHO two of the bits are used to
> select the (EP)ROMs. Which leaves us with two free bits: these can be
> used to control two extra address lines which enable you to use 27256s
> instead of 2764s. Piggyback an extra 175 on top of the original one
> and you can use 27512s and still have three free bits for ..... (just
> use you imagination :).
>
I've learned a lot from doing those projects, the Creativision multicart was
a better effort :-)
dott.Piergiorgio
Nov 13, 2011, 12:31:10 AM11/13/11
to
Il 13/11/2011 00:30, Clocky ha scritto:
>
> It's 74LS139 4,5,6,7 are data outputs that go to the EPROM select lines.
>
>> But seeing the photos my first question was: why did you want to
>> replace the 138 with switches? And if you wanted switches, why didn't
>> you connect them to the 138; you then only needed two and wouldn't run
>> the risk of selecting two or more at the time.
>>
>
> 139 ;-)
I was thinking along the same lines... keeping the 74* logic, passing
>
> It's 74LS139 4,5,6,7 are data outputs that go to the EPROM select lines.
>
>> But seeing the photos my first question was: why did you want to
>> replace the 138 with switches? And if you wanted switches, why didn't
>> you connect them to the 138; you then only needed two and wouldn't run
>> the risk of selecting two or more at the time.
>>
>
> 139 ;-)
from an eprom to another became machine-controllable, seems to me...
Best regards from Italy,
dott. Piergiorgio.
Clocky
Nov 13, 2011, 2:09:58 AM11/13/11
to
If I was a more proficient programmer and I had more time, then that would
be the next step.
shifty...@hotmail.com
May 21, 2012, 10:36:06 PM5/21/12
to
I've gotten my hands on 4 2764's and they are all socketed, I performed all the other necessary steps according to your instructions, cutting the jumpers, etc., and I've soldered on the 4 resistors (for the switch I assume) onto the socket.
So now I just have to figure out where the pins go for the switch and I can begin the testing of it.
Any help with this would be greatly appreciated whenever you get the time.
Take care,
Charles
shifty...@hotmail.com
May 25, 2012, 5:29:05 PM5/25/12
to
All help is greatly appreciated, as has been all your past ideas! ;)
Thanks a lot!
Charles
DMackey
Jul 7, 2012, 1:07:26 PM7/7/12
to
On Fri, 25 May 2012 14:29:05 -0700 (PDT), shifty...@hotmail.com
wrote:
>
> Hey Clocky, could you please do me a favor and give me the details of "where exactly" these dip switch conncetions go to? I've connected them to the resistors inside the 16-pin dip socket and nothing happened so I think I may have done something incorrectly someplace. I still need to install the power switch as well (which is a bridge I will cross after I figure out where the dip switches go to) naturally.
> All help is greatly appreciated, as has been all your past ideas! ;)
>
> Thanks a lot!
>
> Charles
Here are some pics of the cart mod I did.
http://www.n2dvm.com/carts/mdesk/md-mod/md-mod.html
wrote:
>
> Hey Clocky, could you please do me a favor and give me the details of "where exactly" these dip switch conncetions go to? I've connected them to the resistors inside the 16-pin dip socket and nothing happened so I think I may have done something incorrectly someplace. I still need to install the power switch as well (which is a bridge I will cross after I figure out where the dip switches go to) naturally.
> All help is greatly appreciated, as has been all your past ideas! ;)
>
> Thanks a lot!
>
> Charles
http://www.n2dvm.com/carts/mdesk/md-mod/md-mod.html
shifty...@hotmail.com
Jul 13, 2012, 6:25:14 PM7/13/12
to
GREAT! That "DOES" explain a lot as to "why" I don't appear to be receiving any signal as I installed the resistor improperly. hehehehe
I also have one final question that refers to the "switch portion" of that photo. On the front side you gave an excellent photo, but what does the backside pins look like? Are hey "all soldered together" the way mine is for grounding purposes? Just curious.
Thanks again Mack and have a great weekend!
Charles
On Saturday, July 7, 2012 10:07:26 AM UTC-7, DMackey wrote:
> On Fri, 25 May 2012 14:29:05 -0700 (PDT), shifty...@hotmail.com
> wrote:
>
> >
> > Hey Clocky, could you please do me a favor and give me the details of "where exactly" these dip switch conncetions go to? I've connected them to the resistors inside the 16-pin dip socket and nothing happened so I think I may have done something incorrectly someplace. I still need to install the power switch as well (which is a bridge I will cross after I figure out where the dip switches go to) naturally.
> > All help is greatly appreciated, as has been all your past ideas! ;)
> >
> > Thanks a lot!
> >
> > Charles
I also have one final question that refers to the "switch portion" of that photo. On the front side you gave an excellent photo, but what does the backside pins look like? Are hey "all soldered together" the way mine is for grounding purposes? Just curious.
Thanks again Mack and have a great weekend!
Charles
On Saturday, July 7, 2012 10:07:26 AM UTC-7, DMackey wrote:
> On Fri, 25 May 2012 14:29:05 -0700 (PDT), shifty...@hotmail.com
> wrote:
>
> > Hey Clocky, could you please do me a favor and give me the details of "where exactly" these dip switch conncetions go to? I've connected them to the resistors inside the 16-pin dip socket and nothing happened so I think I may have done something incorrectly someplace. I still need to install the power switch as well (which is a bridge I will cross after I figure out where the dip switches go to) naturally.
> > All help is greatly appreciated, as has been all your past ideas! ;)
> >
> > Thanks a lot!
> >
> > Charles
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