On Tue, 11 May 2021 11:29:54 -0400, Andreas Kohlbach <ank@spamfence.net> sprachen:

>Apparently 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!

------------------------------------------------------------------------

if love is a drug, then, ideally, it's a healing, healthful drug... it's
kind of like prozac is supposed to work (without the sexual side
effects and long-term damage to the brain and psyche)

On Thu, 24 Jun 2021 19:40:13 GMT
greenaum@gmail.com wrote:

> 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.

There's another reason - colour would have made the bit shuffling
*much* more complex - the ones with CPUs were running flat out as it was so
the games would have slowed down, as for the dedicated chips - they were
maxed out too colour would have been too much logic.

> Still I reckon colour would have stood out in the arcade. But maybe any
> screen at all did, and that was enough.

The original space invaders had a B&W screen with a gel filter at
the bottom to make the invaders change colour when they got close.
Strangely the screens were at the bottom facing up, what the player looked
at was a mirror at 45 degrees.

--
Steve O'Hara-Smith | Directable Mirror Arrays
C:\>WIN | A better way to focus the sun
The computer obeys and wins. | licences available see
You lose and Bill collects. | http://www.sohara.org/

On Thu, 24 Jun 2021 19:40:18 GMT, greenaum@gmail.com wrote:
>
> On Tue, 11 May 2021 11:29:54 -0400, Andreas Kohlbach <ank@spamfence.net> sprachen:
>
>>Apparently 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.

If I only knew. Cannot verify my claim other than

| MAME can emulate many different central processing units (CPUs) and
| associated hardware.

from its Wikipedia page. May be I misinterpreted that as can *only*
emulate CPUs.

The other thing is that Gun Fight from 1975 existed in two versions. One
with discrete logic, and a newer version with a CPU. It's supposed to be
the first game ever using a CPU (microprocessor unit), and this IIRC the
oldest game MAME can emulate.

Another example is the popular Breakout from 1976, which isn't emulated
(due to not having a CPU?). Breakout II then from 1978 is emulated
(because it has a CPU?). That's where I drew my conclusions from.

There were many questions about the popular game Monaco GP and MAME. The
answer was always that MAME does not support this because it used TTL.

As morbid side note, 1992 the game Ayrton Senna's Super Monaco GP II was
released for some video game consoles. Not two years later Senna died in
a car crash.

> Though that said the "AM" stands for "arcade machine, they let the "M"
> for "multiple" take precendence over that way back when.

MAME merged with MESS (Multi Emulator Super System) but the new program
retained the name MAME (Multiple Arcade Machine Emulator).

> 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.

Games becoming more mechanical as you go back in time. I don't think you
can emulate any of these.

[...]

> Wow, pardon the long post!

No problem. Although trimming a lot (which I mostly agree to) I enjoyed
reading.

> 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!

What happens in six weeks?
--
Andreas

https://news-commentaries.blogspot.com/

Ahem A Rivet's Shot <steveo@eircom.net> writes:
>On Thu, 24 Jun 2021 19:40:13 GMT
>greenaum@gmail.com wrote:
>
>> 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.
>
> There's another reason - colour would have made the bit shuffling
>*much* more complex - the ones with CPUs were running flat out as it was so
>the games would have slowed down, as for the dedicated chips - they were
>maxed out too colour would have been too much logic.
>
>> Still I reckon colour would have stood out in the arcade. But maybe any
>> screen at all did, and that was enough.
>
> The original space invaders had a B&W screen with a gel filter at
>the bottom to make the invaders change colour when they got close.
>Strangely the screens were at the bottom facing up, what the player looked
>at was a mirror at 45 degrees.

Which allowed a smaller cabinet footprint, IIRC.

On Fri, 25 Jun 2021 14:21:59 GMT
scott@slp53.sl.home (Scott Lurndal) wrote:

> Ahem A Rivet's Shot <steveo@eircom.net> writes:

> > The original space invaders had a B&W screen with a gel filter at
> >the bottom to make the invaders change colour when they got close.
> >Strangely the screens were at the bottom facing up, what the player
> >looked at was a mirror at 45 degrees.
>
> Which allowed a smaller cabinet footprint, IIRC.

I can see how it would - very clever whoever came up with that! I
imagine the target footprint was that of the typical one armed bandit.

--
Steve O'Hara-Smith | Directable Mirror Arrays
C:\>WIN | A better way to focus the sun
The computer obeys and wins. | licences available see
You lose and Bill collects. | http://www.sohara.org/