A8 vs C16/Plus4

[oky2000]

Despite what you may think I do not know much about the +4 or C16 machines, I don't own one anymore (very few good games and was offered a lot for my mint boxed C16 and +4 units to refuse)

 

But there have been a few comments here and their about similarities.

 

First A8 had 128 colours (yes 256 very quickly after I know) C16 had 121 and both have similar CPU speeds. No sprites on C16 but char mode of C64. Not sure on pixel scroll and not sure on sound (inferior to SID and there are SID mods for +4 machines)

 

Can we have a sensible comparison of the two different machines? I would be fascinated to know if there is a version of Rescue on Fractalus for C16/+4 (there was Spectrum and Amstrad CPC version as well as Apple/IBM/C64/A8) just to see if it made a good game.

 

I don't know that much about C16 games, there was a rubbish version of Commando for C16 but also a +4 only version too which was much better. So maybe we say A8 vs Plus4 then for ultimate comparison unless we talk about 16k Atari 400 from 1979 yes?

 

Please no fan boys! This is one subject I would like some experienced users comments from the technical side (maybe go in programming forum? I don't know)

Edited May 29, 2011 by oky2000

[Rybags]

I've got a Plus4, it's a real nice looking machine, except those cursor keys just utterly suck to use.

 

The CPU speed is identical, although the Plus4 is slightly slower due to DMA from a default OS screen point of view.

 

The sound is "primitive" - essentially you have pure tones, and the noise is a sort of mix of Atari's distortion types 8 and 2. Due to how the sound hardware works, you can convert Plus4 sounds to Atari 16-bit values very easily with a few bitshifts. Plus4 also has the "forced volume" feature so you can play back samples.

 

Graphics - the screen aspect ratio is identical to what an Atari has when showing 25 lines of standard width text, although the display on the Plus4 is shifted slightly to the right, they don't bother with "margins" for the editor.

 

Although TED is a fairly primitive graphics chip (except for the attributes and lots of colours), there are tricks to get it to do interlace and you can also fool it into doing more than a 200 pixel high graphics window.

There's also C-64 alike tricks like FLI to force more attribute fetches, but the Plus4 does 2 scanlines of attribute fetches so you need to consider that.

 

Colour use is actually a bit more restricted than C64 because you have a full byte describing a single attribute value, so in bitmap multicolour you only get 2 variable colours per cell and 2 are controlled by colour register.

The colours themselves have better saturation than Atari's colours, so pics look a bit more vibrant.

 

The OS and Basic is somewhat more advanced than the C64 but by default you still get the same crappy tape/disk I/O speeds although turboloaders do exist.

 

The joystick ports for whatever stupid reason use round plugs. Commodore's excuse was reduced RFI but the truth is that electrically their the same as the 9-pin standard but just force you to use a C= joystick or make/buy an adaptor for your old ones.

 

The games - there are very few good 16K games. The 16K Atari 400 utterly trounces the 16 in that regard even if you ignore cartridges.

There are some quite good 64K games but even in many "high-end" games you can see the machine suffering due to lack of sprites.

The overall catalog is somewhat thin compared to C64 or Atari but there are quite a few games from ~ 1984-1990 that Plus4 has and Atari missed out on.

 

The Plus4 has H/VScrolling in similar fashion to the C64, and also Raster IRQs. No WSYNC but there's a scanline Horizontal register which you can read and use the value to do a soft delay so accomplishing a similar function.

[oky2000]

Very interesting, thank you for posting that information.

[sack-c0s]

I think the C16 would've given the Atari 400 something to think about - but sadly it's actually a more recent machine than the C64 produced in a blind panic as a knee-jerk response to machines like the ZX spectrum. It probably could've had some great software to rival the Atari but people were already on the C64 by this point and it all seemed like a step backwards (no SID, no hardware sprites, limited memory), so it got overlooked.

 

That said the C16 was my first ever machine, so I do have a soft spot for it, but it was the wrong machine at the wrong time.

 

From a technical point of view colourwise it's almost like if you had the Atari colour range and the C64 placement flexibility, but it doesn't have any hardware sprites. The soundchip has barely evolved from the VIC20 which is also a bit of a letdown - but given that it was aimed at taking on the 16/48k spectrum *any* sound was an improvement for the target market.

 

It did have the advantage that some devs practised their trade on the C64 and then produced superior C16 versions afterwards with their increased skill (big mac for instance is much better on the C16), but you couldn't help but envy your C64 owning friends.

 

so yeah... if I was making an informed choice about which machine to pick up rather than being a 5 year old kid with his face pressed against the Dixons shop window mesmerised by a flashing cursor I would probably have chosen the Atari, but seeing as machine are cheap and plentiful these days it's well worth picking one up should the chance come along.

[Rybags]

C= US, and Atari for that matter didn't particularly care about the Spectrum. Outside Europe, that machine was practically non-existant.

 

The Plus4 was seen by some within post-Tramiel Commodore as a successor to the C64.

It could have been if it was made downward compatible which obviously would have meant having sprites and SID sound.

 

Given that it came along when the 16-bit era was kicking off, you'd probably have been talking about a machine that cost almost as much as an Amiga, so whatever way you look at it, failure was always an option.

 

The Plus4 is virtually unrivaled among 8-bitters for static graphic capability, but that's it's trump card. When it comes to what matters for gaming, it doesn't quite have what it takes to match the A8 and C64 - ie ability to have scrolling/sprites with little CPU usage, and proper sound/music.

[oky2000]

All I know is Jack Tramiel basically wanted a replacement for the VIC20 to clean up at the low end. So that was meant to be a $60-70 retail machine with the rubber keys like the Aquarius/Spectrum otherwise identical to the C16 as we know.

 

I think had Commodore not messed about and tried to make such a hash of the whole project it would have been a nice machine for the price. Despite the A400 being a 1979 machine I suppose the retail cost of the 600XL vs $70 C16 is what we need to think by that's all hypothetical.

 

I don't think it is as powerful as the 600XL/400 models except possibly if it has a C64 style char mode for very flexible total on screen colours, but I don't know so I am hoping we can have a nice discussion between the machines.

 

I have seen now it has pixel scroll so really it's the sound and the sprites that are different to A8/C64.

 

xe03 is a very impressive C16/Plus4 game though considering the limitations of TED chip as I understand it so far.

[oky2000]

 

so yeah... if I was making an informed choice about which machine to pick up rather than being a 5 year old kid with his face pressed against the Dixons shop window mesmerised by a flashing cursor I would probably have chosen the Atari, but seeing as machine are cheap and plentiful these days it's well worth picking one up should the chance come along.

 

I think it's important to remember the C16 has never been fully exploited to maximum potential at the time (even worse than the A8 which did have some high budget USA games) from people like Anco, very similar to how badly the Acorn Archimedes was treated with many sub-par coding efforts despite that machine being superior to relative Amiga models on sale for a similar price. That said I am still inclined to agree I suspect the A8 is better due to sophisticated DLIs and other strange things on top of the same CPU speed. I wonder if there could have been something like the routines Chris Butler so effectively produced based on the C64 char based screen setup, Space Harrier remade for C16 with the same effort as the A8 version. We will never know I guess.

 

I will pick one up again one day though, I have about 150 games, two joystick adapters, 3 datasettes, all the manuals, few carts etc etc so just need a dirt cheap C16

[Rybags]

Xeo3 is great and all but remember the sound you generally hear is TED + VIC. TED only with that game = sfx only.

 

I think that project has stalled - it would be a great game to convert to A8 although 128 characters means it wouldn't be so straightforward.

[oky2000]

One thing I would like to ask is...if the C16 has 121 colours because there are 8 shades of 16 colours and black = black so you get 121 not 128 (8 shades of black!) how did the original 128 colour A8 chipset get 128 colours not 121? Obviously this then became 16 shades of 16 colours yes (?) so how does it not become 241 or 121 colours in reality?

[oky2000]

Xeo3 is great and all but remember the sound you generally hear is TED + VIC. TED only with that game = sfx only.

 

I think that project has stalled - it would be a great game to convert to A8 although 128 characters means it wouldn't be so straightforward.

 

Ahh yes the old SID plugin, many demos do that too.

[Creature XL]

One thing I would like to ask is...if the C16 has 121 colours because there are 8 shades of 16 colours and black = black so you get 121 not 128 (8 shades of black!) how did the original 128 colour A8 chipset get 128 colours not 121? Obviously this then became 16 shades of 16 colours yes (?) so how does it not become 241 or 121 colours in reality?

Actually, the A8 has only 120 color, as hue 1 is equal to hue 15 BY DESIGN. I just read in another thread.

[Rybags]

For whatever reason, Plus4 has a "White" as well as a "Black". Black is 8 identical blacks, white is dark grey through to white.

 

I think the Plus4 uses a different method to generate it's colour for TV, Atari uses fixed saturation with the colours spread according to phase delay.

Plus4 colours don't seem to have much correlation to the phase delay, in fact the first 8 colours fairly closely match those of the C64.

 

It also has what you might say is a more sensible use of saturation, my guess is that it probably varies among luma values rather than being fixed.

 

[Thorsten Günther]

All I know is Jack Tramiel basically wanted a replacement for the VIC20 to clean up at the low end. So that was meant to be a $60-70 retail machine with the rubber keys like the Aquarius/Spectrum otherwise identical to the C16 as we know.

 

To be precise, that's more likely the C116 as we know it

 

 

This is - so it seems - the original model, but was cancelled after a limited run in favour of the C16. The small size of the C116 may partly explain the non-standard joystick ports (as opposed to Amstrad's deliberate deviation from the standard in the Speccy +2/+3 - using standard plugs with an incompatible pinout), for as you can see here

 

 

the C116's back side has hardly any space left for further/larger connectors.

 

Thorsten

[sloopy]

there is plenty of room for two DB-9's there... one of the biggest problems with that machine was lack of useing common connectors for peripherals...

 

sloopy.

[emkay]

One thing I would like to ask is...if the C16 has 121 colours because there are 8 shades of 16 colours and black = black so you get 121 not 128 (8 shades of black!) how did the original 128 colour A8 chipset get 128 colours not 121? Obviously this then became 16 shades of 16 colours yes (?) so how does it not become 241 or 121 colours in reality?

Actually, the A8 has only 120 color, as hue 1 is equal to hue 15 BY DESIGN. I just read in another thread.

 

 

That is not fully true. It depends on the used displaying device and is only happening with PAL XL computers.

[JamesD]

C= US, and Atari for that matter didn't particularly care about the Spectrum. Outside Europe, that machine was practically non-existant.

It may have been practically non-existent, but it's why the C116 was created according to Dave Haynie.

The Tandy MC-10 was created for the same reason.

 

Some games that have been ported in recent years run better on the Plus/4 than the C64. Elite has better frame rates for example. I couldn't find a video of it though.

 

The sound in many Plus/4 games often reminds me of the 2600.

 

 

Some of the games sound fairly decent but nothing like the SID:

 

A few demos (many use a sid card obviously). Clearly the video capabilities on the Plus/4 aren't bad:

[sloopy]

does this mean i need to pull out my Plus/4?

 

 

sloopy.

[emkay]

Looking at the "Shades" Demo.

It also uses this interleaved drawing as in many C64 demos, suggesting a more fluent movement to the eyes.... making it looking double as fast , while the CPU usage gets lower.

 

Has one ever seen a demo on the A8 using this?

[LoTonah]

I bought a Plus/4 from eBay (Works, but sold as-is). Guess what didn't work?

 

A few years later, I bought another one. Worked for 5 days, and died. A quick search on Google let me know that both computers had crappy TED chips.

 

So I guess it was never meant to be, for me?

[Heaven/TQA]

Looking at the "Shades" Demo.

It also uses this interleaved drawing as in many C64 demos, suggesting a more fluent movement to the eyes.... making it looking double as fast , while the CPU usage gets lower.

 

Has one ever seen a demo on the A8 using this?

 

I can not remember any A8 demo. Maybe simply because in 90s there was a common sense to use every 2nd blank line display lists?

[JamesD]

I bought a Plus/4 from eBay (Works, but sold as-is). Guess what didn't work?

 

A few years later, I bought another one. Worked for 5 days, and died. A quick search on Google let me know that both computers had crappy TED chips.

 

So I guess it was never meant to be, for me?

I bought 2 complete in box and both worked.

[popmilo]

I bought a Plus/4 from eBay (Works, but sold as-is). Guess what didn't work?

 

A few years later, I bought another one. Worked for 5 days, and died. A quick search on Google let me know that both computers had crappy TED chips.

 

So I guess it was never meant to be, for me?

I had similar problems, but fortunately heard about easy fix

 

All it needed was to push CPU and TED firmly into sockets...

 

It turns out they tend to loosen and loose contact after 20 years

[sack-c0s]

The Plus/4 tends to be failrly reliable, but the C16 easts through TED chips like nobodys business for some reason

Edited June 2, 2011 by sack-c0s

[barnieg]

A Long time ago me and my brother used to "repair" Commodore 64's with friends due to all the main chips been socketed, there was a good chance of getting a fully working 64 from 2-3 broken ones!

 

Barnie

 

 

I bought a Plus/4 from eBay (Works, but sold as-is). Guess what didn't work?

 

A few years later, I bought another one. Worked for 5 days, and died. A quick search on Google let me know that both computers had crappy TED chips.

 

So I guess it was never meant to be, for me?

I had similar problems, but fortunately heard about easy fix

 

All it needed was to push CPU and TED firmly into sockets...

 

It turns out they tend to loosen and loose contact after 20 years

[barnieg]

 

so yeah... if I was making an informed choice about which machine to pick up rather than being a 5 year old kid with his face pressed against the Dixons shop window mesmerised by a flashing cursor I would probably have chosen the Atari, but seeing as machine are cheap and plentiful these days it's well worth picking one up should the chance come along.

 

I think it's important to remember the C16 has never been fully exploited to maximum potential at the time (even worse than the A8 which did have some high budget USA games) from people like Anco, very similar to how badly the Acorn Archimedes was treated with many sub-par coding efforts despite that machine being superior to relative Amiga models on sale for a similar price. That said I am still inclined to agree I suspect the A8 is better due to sophisticated DLIs and other strange things on top of the same CPU speed. I wonder if there could have been something like the routines Chris Butler so effectively produced based on the C64 char based screen setup, Space Harrier remade for C16 with the same effort as the A8 version. We will never know I guess.

 

I will pick one up again one day though, I have about 150 games, two joystick adapters, 3 datasettes, all the manuals, few carts etc etc so just need a dirt cheap C16

 

A C16 or Plus 4 is on my list of machines I would like to get hold off once I've found some space for the Atari 8-bit stuff (and got rid of some redundant clutter!), it would be interesting to see what the machines could do when pushed.

 

Barnie