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hloberg

any Plus4 C264 programmers on this forum?

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lately I started playing around with the Plus4. taken on it's own it's not a bad little computer. large amounts of memory, good graphics, feature laden BASIC and access to Commodores faster peripherals. if there never been a C64 it might done well. but, as with having a sibling who's the high school quarterback, student president and valedictorian it just couldn't compare to it's older brother C64. Anyway, I'm going to do some programming and wonder if anyone else is out there doing the same?    

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Not really. I ported my music player to Plus/4 once, but that's all I've done. Never really liked the system, though I've seen most recent games that you can get quite colourful displays and software sprites.

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Sort of.  I have a real one and I researched the capabiltiies to the point of sufficiently being able to fairly quickly port 2 games to the Atari (Quadrillion and Spectipede).

 

The hardware is sort of similar to the Atari 8-bit, identical CPU speed but slightly slower (net) due to the extra badlines for attribute fetches.

Advantage of 256 characters (and switchable to 128 like Atari without need for 2K Rom just to generate the inverse chars) and the already mentioned attributes.

Disadvantage of inferior sound (though translating Plus4 sound to Atari 16-bit paired channels very easy thanks to identical clock speed), and no sprites which goes a long way to explaining the realtive poor game quality vs Atari and C64.

 

But, sprite stuff aside, most of the video hardware exploits that work on C64 also work there, e.g. to do stuff like extra picture colour through forced attribute refresh, DMA delay techniques to allow better coarse scrolling granularity, HScroll change per scanline to give the impression of better resolution (similar to our TIP modes).

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On 1/5/2020 at 12:26 AM, Rybags said:

Sort of.  I have a real one and I researched the capabiltiies to the point of sufficiently being able to fairly quickly port 2 games to the Atari (Quadrillion and Spectipede).

 

The hardware is sort of similar to the Atari 8-bit, identical CPU speed but slightly slower (net) due to the extra badlines for attribute fetches.

Advantage of 256 characters (and switchable to 128 like Atari without need for 2K Rom just to generate the inverse chars) and the already mentioned attributes.

Disadvantage of inferior sound (though translating Plus4 sound to Atari 16-bit paired channels very easy thanks to identical clock speed), and no sprites which goes a long way to explaining the realtive poor game quality vs Atari and C64.

 

But, sprite stuff aside, most of the video hardware exploits that work on C64 also work there, e.g. to do stuff like extra picture colour through forced attribute refresh, DMA delay techniques to allow better coarse scrolling granularity, HScroll change per scanline to give the impression of better resolution (similar to our TIP modes).

thanks for the review and how it compares to the Atari 8-bit which I am familiar with. if you kinda look at the +4 on it's own it's not that bad. I'm not at all familiar with the C64 so the exploits you pointed out will be new to me. BTW, do you have a post of the source of your games you translated. did the games have on the Atari use P/M that you converted over over character graphics?  

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From memory no PMGs were used.

Spectipede was created by generating source from disassembling a memory dump from running the game in emulation, it has VBXE colour map enhancement but will also work on legacy hardware.  There's a 320 and 160 pixel version.  I don't think I released source for it.

 

Quadrillion was created by using the original Plus4 source code, it has VBXE colour map as well as bitmap graphics (title).  It works on VBXE machines only as it also relies on the blitter to remap the bitmap graphics.

 

Souce code for Quadrillion should be obtainable from the ZIP file as an example in the VBXE software release packages.

http://spiflash.org/node/10

Edited by Rybags
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On 1/5/2020 at 7:26 AM, Rybags said:

The hardware is sort of similar to the Atari 8-bit, identical CPU speed but slightly slower (net) due to the extra badlines for attribute fetches.

 System Clock Doubling


 For increased processor throughput, the system clock output from TED doubles
 frequency from 894KHz (NTSC) to 1.788KHz (NTSC), during non−display times.
 The horizontal position register counts 456 dots, 0 to 455. During counts of
 400−344, wile in raster lines 0 to 204, the TED device outputs single clock.
 During this time TED is doing processor handshaking (counts 400−432),
 character fetches (counts 432−304), and dynamic RAM refresh (counts 304−344).
 Outside of this horizontal window TED outputs double clock (1.788KHz). During
 raster lines 205−261 for NTSC (205−311 for PAL), TED outputs double clock at
 all times except horizontal counts 304−344 which are single clock to allow for
 dynamic RAM refresh. If the blanking bit (Register #6) is cleared, the active
 display is cleared, the screen is filled with border color, and double clock
 is enabled at all times except refresh.
 

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Hi
My first home computer was the Commodore +4.  I am even a person who wrote the first emulator for it.  So I have many stories to tell about this computer.
People often treated the Commodore series 264 rather wrongly.  It was quite a successful series, some ppl estimate that there were about 2 million units produced.  Some sources reduce this number twice.  In some countries and especially in Germany and Hungary it was a quite popular home computer.  This result cannot help but surprise because the Plus4 got very poor ads in the USA.  Those ads still affect ppl judgement about this machine.  However the ads were rather so bad because this series was Jack Tramiel's computers.  He announced them only several weeks before he left Commodore.  He wanted a killer-computer.  The low-end model the C116 should have price below $50 and the middle model the C264 - below $80.  If he had succeeded these computers could have purged 8-bit market.  Maybe the ZX Spectrum, Atari 800, MSX, Tandy Color, and even Apple II could have been purged like the TI-99/4A was purged before.  However he left Commodore and a war started between him and his former company.  Commodore owner Irving Gould made a lot to make Jack reputation weaker.  Stopping the expected success of the Commodore 264 was a part of means of the war.  Commodore stopped selling the C116 and so it is really a rare computer now.  They changed the middle level C264, they added poor quality ROM productivity software (spreadsheet, text editor, data base, and diagram builder) to it and increased its price about three or even four times.  They cancelled the top model C364 and invented the most mass produced C16 which used the C64 case.  The C16 and C116 had only 16 KB of RAM and a lot of software was written fitting this limit.  The production of the Commodore 264 were lasting only two years in the 1984-85.
The Commodore 264 has almost the same graphics as the C64 but without sprites.  However graphics of the C264 has several advantages over the C64: it uses 121 colors and it can be programmed very flexible.  For example, it became possible to expand screen up to 336x254 raster
https://www.youtube.com/watch?v=BViU4PRMl6E
It also became possible to use interlaced graphics which is quite good for pictures.  I dare to give several links to example of the plus4 graphics 
https://www.youtube.com/watch?v=g4sWBcjr--k
http://plus4world.powweb.com/software/VDC_Challenge
http://plus4world.powweb.com/software/LOTR_Hobbit_Art
There is a projects which uses the plus4 for streaming an external video.
The audio capabilities of the plus4 generally is not very impressive but it is capable to play digital samples quite good.
Some demos for the plus4 are real masterpieces, for example https://www.youtube.com/watch?v=SnDX0reRdeM or https://www.youtube.com/watch?v=975LSPRauVY
The Plus4 CPU uses a tricky way to increase its speed, it can double its frequency whenever it is possible.  So this increases its frequency from inferior 0.88 MHz to acceptable 1.11 MHz (screen on) or even 1.7 MHz (screen off).
The Plus4 Basic is quite good it has powerful commands for graphics, disk drives, structural programming, audio, etc.  It is also integrated with ML monitor which allow cheap and easy ML program development.  I wrote my first ML programs using this way, for example http://plus4world.powweb.com/software/Life_V1_01
The Plus4 Basic is a bit slow, it is even slower than the C64 Basic.  It is because the Plus4 Basic uses RAM/ROM swithing very oftem.  BTW for this reason the C128 Basic is even more slower!
The Plus4 PAL has an ability to be turned in super turbo mode which switches CPU to incredible 2.2 MHz and this makes it one of the fastest 8-bit computers.  However it is quite likely that nobody knew about this mode in the 80s. :)
The Plus4 has quite many good games, for example, https://www.youtube.com/watch?v=pEU2CXGiTBk - it is for 16 KB RAM!  Indeed the absence of hardware sprites makes its game graphics often less smooth than graphics of the C64 or Atari 800.  However total number of games is thousands.  I can point on one quite new game - https://www.youtube.com/watch?v=q4Z9NmmRNmg
For the C264 was developed a special fast disk drive the C1551.  It was possible to run GEOS from it.  However GEOS for the Plus4 misses some important pieces of software.  The Plus4 can also use RS-232 at 19200 bps.  It is possible to attach a Centronics printer directly to it.
Indeed if somebody has some specific question about the plus4 I can try to answer it.
Sorry maybe I have been too wordy. ;)
 

Edited by vol
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 👍 Thanks for all the info on the +4 & C264. 👍 A very intriguing little computer. 

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+4 was my first computer, my parents bought it, probably swayed by the "incredible" built in software and no doubt told it was good for education or something. I only really played games on it so a C64 would have been better. Still, it was a fun machine and did me ok until I saved up for a 500

 

Those colour images in higher res are very impressive!

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Those two demos are unreal!!! Could easily pass for "good" Amiga 500 ones!

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Hi good afternoon.
i play with the plus4 and want to compile the madpascal demo.

how is the madpascal called for the plus4?
I have madpascal on win10.

 

Thank you.

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