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Area 5150: New IBM PC+CGA demo

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First post, by VileR

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I know some of you have seen this already, but for those who haven't...

7 years after 8088 MPH, we finally managed to return to your favorite demo platform, put together a release, and compete at a live demo party again. Here's AREA 5150: a demo for the original IBM PC (4.77MHz 8088), CGA video (targeting RGBI TTL monitors this time), PC speaker, 570K+ free RAM.

This is the party version, released by CRTC+Hornet on 6 Aug. at Evoke 2022, voted 1st in the Alternative Demo compo.

area5150a.webp

With the time it took us, this was truly like giving birth to an elephant. But I suppose we did manage to teach it to tap- break-dance. 😀

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Reply 2 of 38, by keropi

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This is mind blowing 😮
Congratulations on yet another software marvel!
If these demos were created back in the day people would think they are fake 🤣 🤣 🤣

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Reply 3 of 38, by VileR

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Pierre32 wrote on 2022-08-15, 03:04:

PCM over PC speaker in that last section?

Technically PWM, but yes, PC speaker only. Though it's a different engine than the mod player used in 8088 MPH - it's single channel w/one sample per scanline (15.7KHz sample rate, the same as the CRT's horizontal refresh frequency). Uses less CPU, so there are more cycles available for on-screen action.

That part was by far the most technically challenging one in the demo, since the music playback and the 'any-scanline-anywhere' video mode both require extreme precision. That's all reenigne's doing, and once we have a final version he'll hopefully elaborate on how it was done (and how it was debugged - there was custom hardware involved). 😉

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Reply 4 of 38, by VileR

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keropi wrote on 2022-08-15, 06:13:

This is mind blowing 😮
Congratulations on yet another software marvel!
If these demos were created back in the day people would think they are fake 🤣 🤣 🤣

Thanks! I tend to imagine the reactions of the original 5150 engineering team, horrified at such "Atari-like" blasphemies being performed on their respectable Business Machine. 😀

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Reply 5 of 38, by rasteri

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Jaw thoroughly dropped.

I'm guessing with all the cycle-counting shenanigans involved this will never run on anything but an original 5150 😢

The Marble Madness part should be turned into a full port 😀

Reply 6 of 38, by Pierre32

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VileR wrote on 2022-08-15, 09:18:
Pierre32 wrote on 2022-08-15, 03:04:

PCM over PC speaker in that last section?

Technically PWM, but yes, PC speaker only. Though it's a different engine than the mod player used in 8088 MPH - it's single channel w/one sample per scanline (15.7KHz sample rate, the same as the CRT's horizontal refresh frequency). Uses less CPU, so there are more cycles available for on-screen action.

That part was by far the most technically challenging one in the demo, since the music playback and the 'any-scanline-anywhere' video mode both require extreme precision. That's all reenigne's doing, and once we have a final version he'll hopefully elaborate on how it was done (and how it was debugged - there was custom hardware involved). 😉

Excellent, love hearing about details like this. Look forward to more later (hopefully)!

Reply 7 of 38, by leileilol

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😁!

Yes it breaks on PCem v17 but works for most of it, until the elephant melts and the bouncy 3d tetra and then it all goes to resolution-switch flicker hell trying to show the sole scanline being written constantly with no credits music. Thread about that here in hopes this thread doesn't get too derailed with emutalk because this is an amazing demo

apsosig.png
long live PCem

Reply 8 of 38, by Jo22

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rasteri wrote on 2022-08-15, 10:12:

I'm guessing with all the cycle-counting shenanigans involved this will never run on anything but an original 5150 😢

.. and with 8088 CPU only I guess. V20 will get no love? 😢

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Reply 9 of 38, by Grzyb

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rasteri wrote on 2022-08-15, 10:12:

I'm guessing with all the cycle-counting shenanigans involved this will never run on anything but an original 5150 😢

I'm guessing 5150, 5155, 5160, and a bunch of perfect clones.

Reply 10 of 38, by Grzyb

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In the ending screen, I can see the plants from the garden from the unforgettable litograph by M. C. Escher - also used as an example picture in PC Paintbrush, which could be run on an IBM 5150...

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Reply 11 of 38, by VileR

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leileilol wrote on 2022-08-15, 12:33:

😁!

Yes it breaks on PCem v17 but works for most of it, until the elephant melts and the bouncy 3d tetra and then it all goes to resolution-switch flicker hell trying to show the sole scanline being written constantly with no credits music. Thread about that here in hopes this thread doesn't get too derailed with emutalk because this is an amazing demo

Glad ya like it. PCem was in my toolset for dev-testing my own parts... not all the display tricks work 100% (and it won't catch sync issues for example), but it's been enough for quick verifications before moving things over to the real hardware. I'll check out that thread at some point, may be able to help out with some info.

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Reply 12 of 38, by VileR

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Jo22 wrote on 2022-08-15, 15:48:
rasteri wrote on 2022-08-15, 10:12:

I'm guessing with all the cycle-counting shenanigans involved this will never run on anything but an original 5150 😢

.. and with 8088 CPU only I guess. V20 will get no love? 😢

There are relatively few parts that are timed directly by the CPU, and I can say I personally tried to avoid instructions that would break on V20 (at least SALC, anyway). 😉 But yeah, sections like the end credits won't run correctly on anything but a 5150/55/60 (some of the better non-corner-cutting clones might get lucky). The 5140 Convertible is known to have lots of issues throughout the demo, even with the external CGA add-on.

I should also point out that only IBM CGA boards are "officially" supported... cards with subtly-different CRTC models or even with different ROM charsets won't work as intended.

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Reply 13 of 38, by VileR

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Grzyb wrote on 2022-08-15, 18:17:

In the ending screen, I can see the plants from the garden from the unforgettable litograph by M. C. Escher - also used as an example picture in PC Paintbrush, which could be run on an IBM 5150...

waterfal.png

Ha, interesting! It's not a direct reference, not consciously at least, but Escher's work did inspire the original Marble Madness game so there's still a roundabout connection in a way...

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Reply 14 of 38, by dr.zeissler

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Tandy 1000 rl/hd and EuroPC1 with Ram-Extension are incompatible for most parts of the demo. The "water" at the end looks so damn good.
Commodere A2088XT Bridgeboards will also be problematic even with a real CGA-card in it. Don't know what about a 1060sidecar, an old Amstrad or Commodore PC1, or AtariPC.
btw: using a real 1084 on my schneider euroPC or tandy 1000 does not make a difference to my normal setup with nec 71vm connected to an adapter. (same scenes work or do not work)

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Reply 16 of 38, by VileR

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Yes, it's mostly based on that but with additional MC6845 mischief for things like the smooth 60Hz motion, split-screen modes, or "over-the-border" (overscan area) graphics. 😉

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Reply 17 of 38, by dr.zeissler

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I ordered a Cga card, it‘s Not a Real ibm but it has the same Chip.

Retro-Gamer 😀PowerMac 6100-66/Houdini 486/66 - G4 Cube 450/Rage128pro OS9.0.1 - Macintosh LC/Apple IIe Card OS6.0.8 - Acorn A4000 Archimedes - Unisys CWD 486/66 + Aztech Washington