Amstrad CPCnext: Would you buy one?

[GUNHED]

Here my English text of the Nova expansion:

Nova - English
==============

Nova nvRAM and Real-Time-Clock expansion
========================================
Shinra HP : https://pulkomandy.github.io/shinra.github.io/nova.html
Wiki-Forum: https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/nova-nvram-rtc-for-amstrad-cpc-latest-news-from-pulkotronics/
SchemaNova: http://pulkomandy.tk/drop/nova_cpc_nvram.pdf
PulkoMandy: https://pulkomandy.tk/drop/

Technicals
==========
This interface includes 32KB of NVRAM and a real-time-clock
(because NVRAM chips have that).

nrRAM/RTC chip: M48T35Y-70MH1F.
The yellow chip itself tells: ST9906, M4T28, BR125H1
This is the M4T28 BR125H1 battery with 4 pins. Clickable.

Port
----
The interface uses port &FE82 for mapping the NVRAM in and out.
It is possible to map it at any multiple of &2000.

Decoding and Programming of the Nova
====================================
Base address of the nvRAM
-------------------------
The high 4 bits determine the base address of the nvRAM.
Bits 7, 6 and 5 select the RAM address. Bit 4 is set to 0.

 OUT &FE82,&0x   / to map at &0000-&1FFF
(OUT &FE82,&1x) /
 OUT &FE82,&2x   / to map at &2000-&3FFF
(OUT &FE82,&3x) /
 OUT &FE82,&4x   / to map at &4000-&5FFF
(OUT &FE82,&5x) /
 OUT &FE82,&6x   / to map at &6000-&7FFF
(OUT &FE82,&7x) /
 OUT &FE82,&8x   / to map at &8000-&9FFF - \ used for FutureOS
(OUT &FE82,&9x) /                           \OUT &FE82,&8B
 OUT &FE82,&Ax   / to map at &A000-&BFFF
(OUT &FE82,&Bx) /
 OUT &FE82,&Cx   / to map at &C000-&DFFF
(OUT &FE82,&Dx) /
 OUT &FE82,&Ex   / to map at &E000-&FFFF
(OUT &FE82,&Fx) /

The enabled NVRAM replaces 8KB of RAM/ROM with its own contents.

Select the 8 KB block of nvRAM
------------------------------
The low 4 bits select the 8KB page.
Bits 3(=1), 1 and 0 do the selection actually.

OUT &FE82,x8 ' map the first  8 KB page
OUT &FE82,x9 ' map the second 8 KB page
OUT &FE82,xA ' map the third  8 KB page
OUT &FE82,xB ' map the fourth 8 KB page (contains RTC)

Switch nvRAM off
----------------
Any other value for the 4 low bits unmaps the NVRAM
and restores the normal RAM or ROM behavior.
Examples: OUT &FE82,&FE or LD A,&FE:OUT (&82),A


Real-Time-Clock
===============
In the fourth page, the last 8 bytes are not normal RAM.
They can be used to read / write the time from the realtime clock.
In the other pages 1-3 there is only RAM.

All values are in BCD format (4 bits for tenths, 4 bits for units)
The data of the RTC can always be read.

Access to the RTC works this way
--------------------------------
Using OUT &FE82,&6B, interface mapped at &6000-&7FFF:

To read the time
----------------
POKE &7FF8,&40  'stops RTC->nvRAM update / write '1' to Read bit 6 (x1xx xxxx)
        'However, looks like this command is usually not needed

year    = PEEK(&7FFF)
month   = PEEK(&7FFE)
day     = PEEK(&7FFD)
weekday = PEEK(&7FFC)
hour    = PEEK(&7FFB)
minute  = PEEK(&7FFA)
second  = PEEK(&7FF9)

POKE &7FF8,&00 \  nvRAM get updated from RTC again
                \ Write '0' to Read bit 6 (x0xx xxxx)

To set the time
---------------
POKE &7FF8,&80 'Stop RTC for writing data into it / '1' to Write bit 7 (1xxx xxxx)

POKE &7FFF,&21 ' year, for 2021
POKE &7FFE,&07 ' month, july
POKE &7FFD,&31 ' day, 31st
POKE &7FFC,&00 ' weekday, Sunday
POKE &7FFB,&15 ' hour
POKE &7FFA,&53 ' minute
POKE &7FF9,&12 ' second

POKE &7FF8,&00 'RTC picks up new data, start RTC / '0' to Write Bit 7 (0xxx xxxx)

Switch Nova RTC off - save power
--------------------------------
To stop Nova RTC function and save current a bit is set.
The STOP bit is the MSB of the seconds register.
Setting it to a '1' stops the oscillator.
The M48T35/Y is shipped with the STOP bit set to a '1.'
When reset to a '0,' the M48T35/Y oscillator starts within 1 second.

In our example this is: POKE &7FF9,%1xxx xxxx
This stops the Nova RTC and saves power.



Compare Nova RTC and FutureOS Time/Date variables
-------------------------------------------------
Second  = &9FF9 - Second  - UHR_SEK EQU &B95B
Minute  = &9FFA - Minute  - UHR_MIN EQU &B95C
Hour    = &9FFB - Hour    - UHR_STU EQU &B95D
Weekday = &9FFC - Weekday - UHR_WOT EQU &B95E
Day     = &9FFD - Day     - UHR_TAG EQU &B95F
Month   = &9FFE - Month   - UHR_MON EQU &B960
Year    = &9FFF - Year    - UHR_JAR EQU &B961

[Cwiiis]

I mean, don't think I haven't thought about it. I've thought about splitting colours in the background, and I've thought about multiplexing the bombs... I want to believe!

I think multiplexing the bombs is just too much and they will have to be printed to the background, or else expect some major sprite flickering to occur. I also would want to use two sprites to add extra colours to the top HUD. I think some limited colour splitting could be applied in mode 1, but there would only be one floating colour and you'd be limited to a few simple line splits. it's an open question whether that would look better or worse than a mode 0 background with accurate colour. The background is not so bad, but it is a bummer to see the bombs rendered chunky, because then you can see they are rendered to the background. There's enough sprites left over that the little 200 points indicators left behind when you collect a bomb could be sprites. All the other sprites should look nearly arcade perfect.

The Master System, since that's our benchmark, has enough sprites to cover all the moving objects, same as the GX. But they'd flicker more often with only four per line. It would also not have enough tile memory to display the backgrounds, and it would blow up the tile memory even worse if you hoped to print the bombs on top without square borders. Worse is that it doesn't have anywhere near the vertical screen resolution and might have to use a vertical scroll like they did for Ms Pac Man. I love the SMS but it is quite stubby, especially in PAL mode.

Also the AY sound chip in the CPC is the same as the arcade board (which admittedly does have three of them. Heck they sounded pretty great in Gyruss when they stacked five of them together). So ok, maybe your hypothetical CPC Next could have double sound chips. But even just one AY gets pretty close to the arcade sound and is better than the SN chip in the SMS which has no bottom notes.

If you're looking to have 3xAY, the PlayCity would do the job - that gives you another 2xAY and you can externally mix them with the onboard AY (or internally in a pre-Plus machine, but mono only I think?). If it's easy to gracefully fall back, might be nice to add support for it? Alcon 2020 did this, though the split of music and sound effects was an obvious one, but I'm guessing your game already blends the two so maybe not such an easy thing to add...

Re a Plus-enhanced port, I wonder if using sprites for all the moving components is actually the most effective use of them, given you already have great-looking 50Hz gameplay working? Perhaps it'd make (some) sense to use sprites for the platforms - it'd be very easy to multiplex in that case as they're mostly identical and you'd have 256 pixels wide worth of sprites per scanline, so they could easily fill the playfield. That could potentially remove some colour restriction elsewhere and give nice-looking platforms. Sprites could also be used for the UI, I suppose, enabling a few more colours/resolution there, and perhaps for bonus indicators - anything that doesn't need to change too often. Of course, this wouldn't ease the RAM burden and you'd end up with a port that runs on even fewer computers... But it'd run on my computer

[Anthony Flack]

I don't think I could multiplex platform sprites and render software sprites at the same time... I already spend most of the screen time drawing. Interesting idea though. Always fun trying to think of how you can stretch the hardware around something.

It would not be difficult to split music and sound effects if I had access to more channels but I do not have any idea how to go about it and I don't have a PlayCity to test on. I'm just using Arkos Tracker for the sound and perhaps it supports it natively; I haven't looked into that. The first snag I'm likely to hit is that the memory bank that holds the music data and Arkos player is full all the way up to &3FFF so I'd have to shuffle a bunch of things around if the Arkos player got any bigger. 

[Cwiiis]

I don't think I could multiplex platform sprites and render software sprites at the same time... I already spend most of the screen time drawing. Interesting idea though. Always fun trying to think of how you can stretch the hardware around something.

It would not be difficult to split music and sound effects if I had access to more channels but I do not have any idea how to go about it and I don't have a PlayCity to test on. I'm just using Arkos Tracker for the sound and perhaps it supports it natively; I haven't looked into that. The first snag I'm likely to hit is that the memory bank that holds the music data and Arkos player is full all the way up to &3FFF so I'd have to shuffle a bunch of things around if the Arkos player got any bigger.

In case you consider giving it a go, programming info is here: https://www.cpcwiki.eu/index.php/PlayCity - It's supported in the CPCEC emulator (that also has a pretty decent debugger) and I suppose you could still purchase one from @TotO (?) if you wanted to test on real hardware. It probably wouldn't make a huge amount of sense to use all 9 channels, rather than using 6 of them - As I understand it, the Play2CPC (which is likely more common?) only provides another 3 channels, as opposed to another 6 like the PlayCity. The PlayCity is supported in Arkos Tracker 2, iirc.

Maybe hardware sprites replacing software sprites is the most obvious thing in that case, with bombs remaining software sprites, as you've suggested. There's more than enough time to update every hardware sprite frame over 3 or 4 frames and leave plenty of time for game logic. More colourful game sprites and a lower RAM requirement would be a nice little bonus for Plus/GX owners

I wonder if you could squeeze in EGX backgrounds with the time saved by not having to manage software sprites... That would certainly be ambitious and interesting... Failing that, perhaps a Paula's Potions style alternating background to get some more colours would be feasible...

[Prodatron]

It would not be difficult to split music and sound effects if I had access to more channels but I do not have any idea how to go about it and I don't have a PlayCity to test on. I'm just using Arkos Tracker for the sound and perhaps it supports it natively; I haven't looked into that. The first snag I'm likely to hit is that the memory bank that holds the music data and Arkos player is full all the way up to &3FFF so I'd have to shuffle a bunch of things around if the Arkos player got any bigger.

PlayCity is only supported by the MultiPSG-Version of the Arkos AKY-Player. AKY is a streamed-based music format similair to YM, which uses more memory than usual modules. If you already use the AKY-variant it should be easy to add PlayCity support.

[Anthony Flack]

I used AKG. No memory for AKY. A cartridge version would be a different story of course. I think the best thing for a Plus enhanced version would be a total rebuild. But obviously whole chunks of code could be copied straight across.

I am looking forward to playing with the Plus features and cartridge format when I actually have some time to do so. 

[genesis8]

PlayCity is also supported by Roudoudou's emulator : ACE-DL

[zhulien]

Foe those with a Mega65, it really is a perfect machine for a great CPC core.  Unfortunately a CPC core isn't here yet.  Proce may out people off, 666 euros to me is ok... but sadly for me they charge a LOT for postage to Australia making it really expensive.  I still bought one and cannot praise the hardware enough.  Spectrum Next can also be a CPC but the keyboard isn't as nice as the Mega65.  If someone can make a Mega65 core? TOBIFLEX perhaps?  That would make a Mega65 a must have CPC if the core supports all the hardware...

Specs here
https://shop.trenz-electronic.de/en/TE0765-06-T001CK-MEGA65-highly-advanced-C64-and-C65-compatible-8-bit-computer

[zhulien]

BTW: About CPC and RAM-Banking you did forget to mention some feature...

8 KB of expansion RAM can be banked in at every multiple of &2000, this enhances banking quite useful! No other computer has that nice little gem. That's what I call Nova-Blast! 

I think multiface 2 does that

[zhulien]

Over-simplifying a bit, but if you imagine that a 16 bit machine needs twice as much memory to deal with the equivalent amount of graphics and so on, an CPC with 64k is like an ST or Amiga with only 128k, and 256k is comparable to a stock Amiga 500. In reality, without audio samples to deal with or whatever else, 128k feels about right for the CPC, 64k is uncomfortably tight and 256k is luxury.

Hm. Isn't the Amiga even more hungry than the ST when it comes to screen memory consumption? I am under the impression that it spends 64k for graphics, whereas the ST stands at 32k. Can't seem to remember where I have read that info, but by quick referencing I see that the Amiga has 4x the on-screen colours per resolution compared to the ST...

The A1000 had 256k onboard ram, so if, say, 1/4 of that is reserved for graphics, then that would make it an exact 16bit equivalent to a 464. Has anyone made any games or demos for that one and only true Amiga, lately?

The Amiga can have 32 colours on screen as opposed to the ST's 16, so it's more like 40K if my maths is right. You could up that to 48K if you're using EHB (nobody does) or a Dual Playfield setup with 7 foreground and 8 background colours.

But anything for an 256K OCS Amiga is a bit rare, it's very tight for memory - a similar situation to the 464 for sure.

That must be an unexpanded Amiga.  These days Amiga 500s can have AGA and almost a gb of RAM

[GUNHED]

BTW: About CPC and RAM-Banking you did forget to mention some feature...

8 KB of expansion RAM can be banked in at every multiple of &2000, this enhances banking quite useful! No other computer has that nice little gem. That's what I call Nova-Blast! 

I think multiface 2 does that

No, MFace2 does exchange the lower ROM, 8 KB SRAM are banked in, BUT at a fixed address. And there are 8 KB used for MF2 ROM. It's different. 

[cwpab]

Considering how many ZX Spectrum based machines there are (The Spectrum, ZX Spectrum Next, the portable ZX Touch... and maybe I'm missing more!), it's starting to feel a bit weird not to have at least one similar product for the CPC.

[Prodatron]

Considering how many ZX Spectrum based machines there are (The Spectrum, ZX Spectrum Next, the portable ZX Touch... and maybe I'm missing more!), it's starting to feel a bit weird not to have at least one similar product for the CPC.

Zx Spectrum Classic/48/128/+2/+3
Zx Spectrum Evolution
Zx Spectrum Uno
Zx Spectrum Next
Zx Spectrum Elements
Zx Spectrum Pentagon

Anyway I have a CPC NG already today, no need to create a new machine.

My CPC probably has greater feature compared to what people were dreaming about when talking about the CPC NG more than 20 years ago:
https://www.cpcwiki.eu/index.php/CPCng
https://fr.wikipedia.org/wiki/Color_Computer_New_Generation

[GUNHED]

Well, I thought the CPCng project was abandoned at planning stage. Did I miss something? Or do you talk about SF3 / RSF3?

[RockRiver]

That I ask to CPCng is something similar that we have with Spec256 or PCWplus

CPC's Mode1 resolution but with mooore colours 16 ? , 256 ? per screen

Mode 2 with more than 2 colours??? Yeahh

To convert existing CPC games to 256colours ?? [Yes like Spec256, ZX Next or ZX ulaX do]

[ I like so much the great work of Ayor61 and others to convert classic CPC games to CPC+ palette... and Kachorro PCWplus ports from ZX and CPC games. But with 8/16 colours now on PCWplus ]

https://enriqueggalvez.itch.io/

So it is needed a new VPU/CRTC/Gate Array, but backwards compatible with CPC/CPC+

 and mooore RAM (VRAM)

That exists nowadays as Atari ST ?? Could be.
Maybe historically the AtariST was the CPCng (french videogame market had this totally clear in mind)
[but no CPC emulator on ST, yes on Amiga]

Maybe Atari ST gives us that we want about colour/resolution ... but we want with Z80.
And that is the ZX Next ? ha ha

So what could be the difference about CPCng ?
The goal is that Roland Perry's team Amstrad's  ANT could have been:
CPC/PCW/CPC+/Pcw16/PCWplus compatibility

All with powerful and quicker Z80, see Habisoft ports for PCW16 : KnightLore and Total Eclipse (PCW16 can give colour and can have HDD)

All of that with/inside FPGA tech, sure. CPCng core for Mister; NeptUNO+; SIDI128 ; ZXtres or similar... and later without bugs in Core we would talk about to put the enhanced system in a nice microcomputer style case and keyboard.


My actual enhanced retro computer is MSXVR (Raspberry Pi as CPU/VPU) that in CPC Virtual Machine has CPR virtual cartridge support; DB9 joystick connector; use usb pads too;
cherry MX switches keyboard with cool retro style keycap ; GUI ; several soundchips from cpc's AY code ... easy zoom to put CPC and others in complete screen without borders ...
several 8bit and 16 bit machines direct support and direct loading from system. Only one click of mouse.
Could run Symbos on MSX or CPC or linux <SymbOS VM>

Sorry but I love too that people do with ZX Next. Remembering powerful Z80 Arcade line.
But today not existing CPC+ fpga core for ZX Next, Mister or other (soon maybe on Mister)(yes there is PCWplus core on Mister and others too)
 yes there is ZX Next and Mega65 cores for fpgas.

Indeed ZX Next and Mega65 use fpga system (and cool cases)

I like enhanced 8bit systems: CPC+; PCWplus; MSX2+,turboR; SAM ; GBcolor ; Apple IIgs ; ZX Next ; Mega65 ; SMS ...

Long Life to 8bit, CPC,  and to us

 cool pixelart and chiptunes

[Pollo]

Maybe historically the AtariST was the CPCng (french videogame market had this totally clear in mind)

The Atari ST is the all-in-one retro computer in terms of games. It has the CPC vibes at times, but it can also have Amiga vibes.

For anyone who is interested in the 8-bit and 16-bit eras but who don't want to mess with multiple machines, it has the best software line-up I think. It mixes the best of the 8-bit and 16-bit computer games.

It is a seriously underrated machine among retrogamers, imho.

[m_dr_m]

> Would you buy a CPCNext

Why not use the CPC core in the ZXNext?

[Pollo]

I have a bitter pill to share with you guys. I started out on the Amstrad CPC, then moved to the Amiga 500, upgraded to the A1200, and finally ended up on a Windows 95 PC.

Do I regret it? Absolutely.

In hindsight, it was a mess. If I had any sense back then, I would have just bought an Atari STF in 1986 and stuck with it until Windows 95 and the 3dfx graphics card came along.

That would have saved me a pile of cash and spared me years of useless distraction.

Wading through the quirks and intricacies of those platforms wasn't "learning" — it was a colossal waste of time.

[norecess464]

Do I regret it? Absolutely.

It's surprising. Maybe the A1200 was the costly step in the process (the one to be avoided) but otherwise, you experienced great parts of the gaming/micro computers history!

[eto]

In hindsight, it was a mess. If I had any sense back then, I would have just bought an Atari STF in 1986 and stuck with it until Windows 95 and the 3dfx graphics card came along.

From a money perspective that would not have been SO different. I went for a STe in late 1989 - and since I did not only play games I had to invest A LOT to make it more useful to me - more RAM, hard disk, 28MHz CPU. And those expansions cost more than I would have had to pay for their Amiga counterparts (as the expansions were a bit cheaper for the Amiga). Instead of the A1200 for me it was the Falcon 030 - I got it (used) in 1994 - and it was more expensive than a A1200. 

And what do you mean with useless distraction? 

[Prodatron]

Back to topic:

My CPC has:
- up to 2MB Ram (Gemini by @PulkoMandy etc.), or up to 1MB internal (iRam1024 by @eto )
- USB interfaces for mouse and mass storage (Albireo by @PulkoMandy etc.)
- up to 2 TB accessible mass storage with FAT32, using IDE, SD or USB devices
- Network interface (M4Board by @Duke , Net4CPC by @d_kef etc.)
- OPL4 sound card (MoonSound and all its clones via Amsdap by @TMTLOGIC ) with 24digi channels and 36fm channels, used for playing Adlib, MOD and other music
- MP3 decoder (MP3MSX, SE-One, SF3, RSF3 etc.) via Amsdap (by @TMTLOGIC )
- Graphic hardware with up to 1024x212 pixels, 512KB Vram, 16-32768 colours, sprites, patternmode, etc. (V9990/Graphics 9000 by various vendors like @TMTLOGIC)
(- oh, and a multitasking GUI OS, which supports all of this at the same time )

IMHO the only missing thing would be a Z80 with a faster clock! This is an issue for the original CPC architecture, but already has been achieved by the CPC-TREX FPGA system.
There may be a project currently underway that would speed up the Z80 clock speed in the CPC without breaking everything else, like this useless 6MHz hack. But this is just an experiment.

So what else should a CPCNG be able to do?
The specifications above are much more than people dared to dream of 25 years ago.

[Pollo]

> And what do you mean with useless distraction?


It felt exciting for sure, and I truly enjoyed it at the time. But I tied myself to heavily proprietary platforms that went nowhere.

How useful is it in real-life to know Z80 assembler, CRTC tricks or how to use CP/M? It's next to none.

All that tinkering didn't translate into lasting, useful skills. In the end, whatever I invested (time, effort, money) was simply wasted.

On the other end, the Atari ST is a fairly modern and standard productivity machine, so at least I wouldn't have been tempted to waste my time on these types of cul-de-sacs.

[Prodatron]

> Would you buy a CPCNext

Why not use the CPC core in the ZXNext?

I hope they provide a faster Z80 as well, similiar to the CPC-TREX, that would be very cool.

[andycadley]

The biggest problem with the Spectrum Next is throwing silly amounts of hardware into it and ending up with an "almost Amiga" - I would hope any CPC "Next" core tried to away from going full V9900 and ridiculously fast Z80 etc because you just end up with a machine which is so powerful you might as well target the Amiga.

I can think of a handful of very small additions to the CPC Plus which would have been ideal QoL features back in the day (for example being able to switch Mode, Palette and whether sprites are enabled on a screen split) that would make for a better machine whilst staying true to the roots. 

[eto]

throwing silly amounts of hardware into it and ending up with an "almost Amiga"

Or you can see it as "what if 16 bit would not have happened so early". Imagine a world where 16 bit CPUs would have been too expensive for home computers and affordable 8 bit options would have stayed relevant for another decade. The Next specs look like a natural evolution of how a low-end 8 bit home computer could have looked like. 8 or maybe even 16MHz CPU would be no surprise. The graphics (resolution, colours, sprites, tiles) etc. also already evolved in the 80s (MSX; Elan Enterprise, consoles) and having something like that in a budget computer doesn't seem to be far fetched for the early 90s. 3 AY chips is an even more "cheap" improvement and perfectly fits a "budget" Speccy successor. 

The more I looked at it the more I liked it. I was tempted until the last minute (literally) but I finally decided against it. I simply know that it would only collect dust on my shelf.