Burgertime curiousity...

[CrazyImpmon]

When I sorted and checked my collection of 2600, I noted that Burgertime cart is very heavy. Most other M Network carts I've taken apart usually had a pcb about the size of US half dollar coin and had one tiny black eproxy covering the ROM chip.

 

When I took apart the Burgertime I was greeted with 4 chips. 2 identical chips opposite of the game connector is probably the game ROM but I'm not sure about the other 2 chips. One is a Toshiba TC5516AP-8 (24 pin IC, I think it's RAM chip) and another is rather large, almost like a CPU. 40 pin IC, marking reads: VTI 0098-0748 VC2032.

 

The board has the silkscreen print:

© M.I. 1983

4518-4229

REV. A

 

BIG GAME

 

What exactly am I looking at? And why with all the circuitry the 2600 game sucks badly graphic wise? All those flickering and flashing square cursor could induce seizures.

[CrazyImpmon]

Decided a picture is worth 1000 words so I'm including a very sharp closeup of the game's gut:

[CPUWIZ]

Dave Akers told me that these were the original run of the carts, they were later replaced with the "blob" style carts for cost reduction purposes. There is another one like that which holds EPROM's instead.

[Thomas Jentzsch]

From Kevin Horton's bankswitching informations:

-E7: Only M-Network used this scheme. This has to be the most complex

method used in any cart! :-) It allows for the capability of 2K of RAM;

although it doesn't have to be used (in fact, only one cart used it-

Burgertime). This is similar to the 3F type with a few changes. There are

now 8 2K banks, instead of 4. The last 2K in the cart always points to

the last 2K of the ROM image, while the first 2K is selectable. You

access 1FE0 to 1FE6 to select which 2K bank. Note that you cannot select

the last 2K of the ROM image into the lower 2K of the cart! Accessing

1FE7 selects 1K of RAM at 1000-17FF instead of ROM! The 2K of RAM is

broken up into two 1K sections. One 1K section is mapped in at 1000-17FF

if 1FE7 has been accessed. 1000-13FF is the write port, while 1400-17FF

is the read port. The second 1K of RAM appears at 1800-19FF. 1800-18FF

is the write port while 1900-19FF is the read port. You select which

256 byte block appears here by accessing 1FF8 to 1FFB.

 

That might expain a bit.

[Tempest]

You talk funny...

 

 

Actually I believe In Search of the Golden Skull was also going to use this type of bankswitching.

 

Tempest

[Thomas Jentzsch]

l

[CrazyImpmon]

the description is very confusing. I guess it's why no one else used that method. I wonder if there is such thing as a one blob version of Burgertime?

 

And I thought multi-load Supercharger game was complicated.

[Turnspike]

* in his best accent* It got Toshiba guts! It work GOOD!

[StanJr]

that was yer best accent?

 

I had no idea about Burgertime being so whacked out! Makes me want to crack one open....

[CrazyImpmon]

Why would you want to? For one thing, it's darned near impossible to open the M Network cart without breaking it. There seems to be 2 different versions of M Network cart: one that looks like Intellivision cart that snaps onto "2600 adapter" (as one really clueless eBayer put it) and another version appears to be fused into one single piece of plastic.

 

Unless you've got duplicate Burgertime, just stick with the picture I got and save yourself the agrivation. Or just get a hacksaw and carefully cut around the base of the so called "2600 adapter"

[CPUWIZ]

I have a blob version of it.

[Smada Bez]

and if anyone would care to see one with the "blobs"...

[Big Player]

Hey, that blobs cart looks suspiciously like my soldering work.

[cschell]

   the description is very confusing.  I guess it's why no one else used that method.  I wonder if there is such thing as a one blob version of Burgertime?

 

And I thought multi-load Supercharger game was complicated.

 

Yes, the Mattel scheme is annoying, especially all that work for the worst version of Burgertime around. Not owning a Burgertime cart, when I got it working on the prototype Cuttle Cart I was convinced something was wrong. It couldn't possibly be that bad could it? That and the fact that I didn't know that the game would pause with a certain difficulty switch setting, which of course was set when I loaded it in the first time.

 

But at least the Mattel scheme doesn't require a state machine. I think the supercharger is still more complicated, after all it has to count changes on the address bus. The joys of working around the lack of clock and r/w lines. (Kevin Horton never got around to reverse engineering the Supercharger scheme, that's why it's not described in sizes.txt.)

 

Chad

[CPUWIZ]

Damn, you beat me to it.

 

[supercat]

But at least the Mattel scheme doesn't require a state machine. I think the supercharger is still more complicated, after all it has to count changes on the address bus. The joys of working around the lack of clock and r/w lines. (Kevin Horton never got around to reverse engineering the Supercharger scheme, that's why it's not described in sizes.txt.)

 

The lack of clock lines is rather a pain, to be sure. Most carts seem to do okay using an address line to control R/W, though at the expense of a lot of address space. I wonder if anyone on any system has used 4A50-style "magic writes" before I invented them? The 4A50 cart does require a state machine clocked by a 14.3818MHz oscillator, but it's not terribly complicated. Even a 16V8 might be able to handle it (though it couldn't do much else).

 

The key to making everything work is a 12-cycle state machine combined with a means of detecting transitions on A0. The simplest way to handle this is to use four registers for the state machine, one to latch A0, and one to latch the output of that. The four-bit state machine runs continuously except that it gets reset whenever the two A0's don't match. Ideally one could simply have the state machine reset whenever A0 doesn't match the latched value, but it's hard to avoid race conditions when doing that. It's still possible to do the job using only five macrocells, but it's tricky.

 

I don't think there should have been any technical hurdles to producing my "magic writes" cart in 1984. I wonder if simply nobody ever thought of it.

[jpfalcon2003]

I actually enjoy Burgertime for the 2600. I really don't think they did a bad job. The inclusion of many screens is awesome I think.