Game oriented machines of '80

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Par fernando.collazo.5682

Master (251)

Portrait de fernando.collazo.5682

24-04-2017, 03:51

Amstrad CPC has some really colorful games, but at the cost of lower resolution (160x200 16 colors) than MSX1, and to me, all the CPC games are slower. The Z-80 runs at 4 Mhz, the locomotive basic is better than msx basic but that´s all. MSX 2 is way better than any other 8-bit computer Cool

Par PingPong

Prophet (3556)

Portrait de PingPong

24-04-2017, 19:02

Yes resolution is lower but color is very good.
The question of vram direct access is over evaluated. That is because you typically continuos small area of vram and the over head of setting vram ptr ismitigated .different is for msx2. Here there is a large amount of vram to manage. A fast blitter is preferable todirect vram access.
But in my mind i mean sw sprites for non scrolling games like vampire killer usas or kpipball not only rpg
Finally for valis i agree. Here the bottleneck is cpu not vdp and the high number of outs needed to be sent to vdp.
Plus valis had the ambition of multilYer scrolling....

Par Wlcracks

Champion (430)

Portrait de Wlcracks

25-04-2017, 07:16

lol screen3 is lower but color is very good

Par PingPong

Prophet (3556)

Portrait de PingPong

25-04-2017, 20:58

Wlcracks wrote:

lol screen3 is lower but color is very good

the (useless) graphic mode with a pixel resolution comparable to a entire charater. :-( also slow to address.

Par PingPong

Prophet (3556)

Portrait de PingPong

26-04-2017, 16:02

the situation is not that worse as you describe. on MSX1 accesses are tipically contiuguos in pratice you set the vram ptr then read a block or write a block of contiguos data. This way the initial overhead is lower. In the worst case scenario effectively you need to compare about 80 cycles to do the same you do in direct accesses with a LD A, (HL) that takes 8 cycles on msx.
On other situations this kind of access can be faster. Take for example a transfer operation where you need to track both source and destination without using LDIR, with the OTIR solution you can free a pair of registers for others uses.

For the other problem ( you have to write color on second run ) this is also true on ZX, the difference is that you need to write 8 times colour data than on ZX. And is this that really slow down the game. If you check the batman game the zx convertion is fast enough and comparable to speccy because there is no color overhead.

writing 8 consecutive color bytes to emulate the speccy can be achieved in vblank area in this way and is the faster way.

call setvramptr
ld a, colourcode
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a

Par AxelStone

Prophet (2765)

Portrait de AxelStone

27-04-2017, 10:32

Think about one thing: thanks to hardware sprites games like Nemesis saga, Zanac or Valis are possible. These games on CPC should be clearly slower. You can compare MSX tile mode vs CPC with the game "Invasion of the zombie monsters", the MSX version is clearl faster than CPC and both of them has good colours.

I agree that CPC is near unbeatable in use of colour, since all is generated by software, but it is a high price to pay to get good arcades with good speed.

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