A nice pic of a disassembled prototype / development Cosmos. I'm going to run through the hardware in outline and then do a bit more detail .... what I think is the detail anyway.
Some of it I just don't know at all, without being psychic, but much of it can be deduced to the extent where you can code for it if you use constants in the assembler code. (Except for the sound ... other than it uses the serial interface I have no idea how it works at all)
As an example, it's impossible to deduce which bits are up down left right on the keyboard without either a ROM dump (and nobody's going to do this !) or access to the PCB and a multimeter (and they're not going to do that either). I sacrificed a cartridge for the Microvision archiving effort (you have to destroy them) but with Cosmos systems going into 5 figures .... not going to happen.
Sometimes this is ropey. I have occasionally made deductions on other machines based on the concept that the designers weren't idiots, and sometimes they've been ... idiots. However, there are some top brains behind this machine, so I suspect it is intelligently designed. Assuming this helps :)
I do have some close ups of bits of the PCB. It is single sided which is quite handy, because you can deduce some things from the single-sidedness - if a signal can't get to the keyboard connector, it can't actually be part of the keyboard circuitry.
The processor. Now virtually everything on the Cosmos gets this wrong ; it isn't a COP411, it's a COP444. You can see it left/centre on the main circuit board with the gold square. It's a 28 pin chip, and a COP411 is a 24 pin chip. The close ups also have "COP444" on it ;-)
I'm not surprised because even a COP444 only has 2k of ROM built in and you have to fit 7 or 8 games (can't remember) into that. Even at a low level of complexity that's not easy.
There is actually a COP411 on the board though. You can't see it in this picture (it's underneath the orange toggle switches on the right/centre. It's an arrangement like the Entex Adventurevision, the little MCU generates sound effects. The two are connected by a protocol "Microwire" which uses the Serial I/O pins on the processors.
Just below the processor, in the middle, is a 7 pin connector that loops round via the ribbon cable and connects to the keypad on the front of the unit.
Below that is the Power Supply unit (most of the left hand side, (and presumably the two capacitors !), and there's a plug on the lower right (which is soldered here but is another connector on the production board) which is connections for the odds and sods - speaker, image selector.
Immediately above the main MCU there is a seven resistor array which connects directly to the display connector (it's the red thing you can just see peeking out from the bottom corner of the display board) and on the top right of the circuit board are the current drivers for the rows. There's 7 across and 8 down (actually 6 down and two seven segment displays).
The thing with the LEDs is the display board, with its 7 x 6 grid and two 7 segment displays (the white box). Directly above this you can see 5 circular pads. These are the contacts for the "cartridges" (actually just the holographic images). Connecting one or more of these pads to the input line (probably the rightmost) selects the game to play - the games are already built into the processor.
This is the purpose of the orange toggle switches - they are a development hack so you can 'select a game' (e.g. connect the pads to the input) without actually having to have different cartridges ; the push button is probably connected to Reset.
The connector is the 16 way ribbon cable that goes round the back of the PCB and plugs into the just visible display connector.
On the right hand side, the grey box is - maybe - the hardware for selecting the 3D Holographic image - the Cosmos can display one of two images. These vary - sometimes it's a game and a game over screen, sometimes it's two ends of a football field.
Below that, obviously, is the speaker.
The other connector that you can't see is a little one immediately above the display connector. This one had me baffled for ages..... more on that later.
No comments:
Post a Comment