Post by Andreas KohlbachApparently I can emulate a PDP-1 (from 1961?) in MAME, although MAME is
supposed to only emulate machines with a microprocessor as CPU. So
machines with i4004 (1971) upwards.
Where did you hear that? I've never heard anything about MAME having some preference for integrated CPUs vs circuit-board ones.
Though that said the "AM" stands for "arcade machine, they let the "M" for "multiple" take precendence over that way back when.
Eventually MAME will be able to emulate any machine that ever existed, including those MAME cabinets that people build. Including
the Morse Code Key, and the bone for hitting other monkeys over the head with.
I never knew, til I'd been into collecting old computers ("retro", -spit!-) for a long time, that Atari, among others, had a whole
line of machines out in the 1970s, using B&W graphics and custom logic circuits, hard-coded to run whatever game. No software,
no CPU.
I can understand doing Pong like that, Pong even lends itself to a TV screen, you draw the bats and everything just by timing as
the electron beam races down the screen. The length of the bats just needs to be a timer, you start it when you begin to draw a
bat, and the time it takes to decay determines whether, when the beam is at the right horizontal column, to draw the bat on this
scanline or not. If the length-timer says "yes", then you do.
You start the length timer according to how far down the screen the bat is to be drawn, affected directly by the player's pot
control. So you reset another timer at the first scanline, then at a rate determined by the control, it waits til the right
scanline to start drawing the bat. That triggers the bat-length timer, which says for how long to draw the bat.
The bat isn't drawn all the time the bat-length timer is on, of course. Only when the horizontal-position of the electron beam
is right where that bat ought to be. When it is, check the bat-length timer, and if it's still on, then we draw one scanline's
worth of bat just there, just a little horizontal slice, like a slice of cheese in an unwieldy Scooby-Doo sandwich.
Anyway... same thing for each bat, and the ball. Similar things for the "goals" if it's a football-type game, I don't think Pong
had that, but the AY-3-8500 based home games, in their millions, did. This is all from supposition and what I've been able to dig
up, I wrote a Pong simulator way back when on PC. It used the "timer" / "scanline" idea, though emulated on a PC, and even had a
couple of the weird effects those units had. Play felt very much like the real thing even if appearances were a bit primitive in
320x200 at 256 colours.
I say "timer", you could use "counter" instead, do it digitally, and use appropriate comparators there. Analogue or digital
doesn't matter much. Atari, in the 2600, were keen to use polynomial counters in everything in it's graphics chip. So that it all
takes the right amount of time to count, I *think*, rather than varying slightly with the varying carries needed for normal
counting. If someone has a better explanation than that, please oblige! Maths not really my thing past the strictly necessary.
Then past Pong, early games used ROMs for little sprites, instead of bats, though not much advance apart from that. I think at
least a couple of them used ACTUAL diode ROM with ACTUAL diodes! On a little PCB, you could see the graphics soldered in there!
Every lit pixel costs the company 2c! Or whatever a diode cost.
Not having software didn't mean you couldn't have RAM or ROM though, then eventually America's favourite washing machine
controller raised it's ugly head! I prefer the Z80 myself. But Atari stuck 6502s in nearly all their early machines. It's a shame
they used B&W graphics, generally black and white, and a mid-grey. Mid-grey would be the default playfield and presumably
be whenever nothing else was sending pixels to the electron beam, it'd default to mid-grey. I suppose B&W CRTs were cheaper,
but the amount of profit arcade games made, surely they could have afforded colour? And make the effort to squeeze a couple more
chips in so we actually got maybe 5 or 6 colours all on the screen at once! Actually yeah I can see why they didn't bother, often
there were very few objects on screen at all, or very few types of object, with multiples of them. Still I reckon colour would
have stood out in the arcade. But maybe any screen at all did, and that was enough.
Prior to that it's the crazy and ingenious world of electro-mechanical amusements. In Blackpool (Brit Seaside resort, the best
one) maybe 15 years ago, on the sea front somebody had set up a bunch of genuine old machines. In exchange for money, he'd give
you a few enormous old pennies to put in their slots to play. You could win those disgusting candy sticks / candy "cigarettes",
but who'd want to? At least make it a lollipop, mate! Did anyone ever like those disgusting things? As kids we only ever bought
them once or twice for a laugh at pretending to smoke.
Anyway, yeah, MAME... the freaky evolutionary effect of open-source, it just thunders ahead like a stampeding mastodon. Linux,
Arduino, MAME, probably the biggest open-source sucesses I think, anyone wanna disagree?
Wow, pardon the long post! Good ol' Usenet! You've got 6 more weeks to think about it, probably, so no worries. It's like the
ooooold days must've been here, very little activity and conversations that stretch over however old long. Nice!
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kind of like prozac is supposed to work (without the sexual side
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