CPCWiki forum

General Category => Amstrad CPC hardware => Topic started by: zhulien on 10:14, 23 February 25

Title: External ez80
Post by: zhulien on 10:14, 23 February 25
As it is possible to use an external cpu on the cpc, would it be possible to use an ez80 at 20mhz and just have massive wait states for internal memory accesses? But it could run full speed at the high memory.
Title: Re: External ez80
Post by: Pollo on 11:20, 23 February 25
Why limiting yourself to the eZ80 when you can already have a powerful ARM chip plugged to the CPC with the PicoCPC, or the M4 board, etc...
Title: Re: External ez80
Post by: zhulien on 08:10, 27 February 25
BBecause Carefully coded your same code can run on internal z80 or ez80 faster
Title: Re: External ez80
Post by: McArti0 on 11:37, 27 February 25
I have a little interface drawn between z84c0020 and cpc with 1byte write cache.
But it is a lot of work, because basically everything has to be separated, including e.g. RD MREQ IORQ because you have to slow down the system for IO and fool GA that you are not doing anything.
So if you're going to do something like that, it's better to do everything in ARM or FPGA 20-25k LUT...

ps. But LDIR speed of 1byte per 1us from fast RAM to VRAM on a regular CPC sounds tempting...
Title: Re: External ez80
Post by: McArti0 on 12:17, 27 February 25
Apart from that, the pinout is very problematic.    ;D
Title: Re: External ez80
Post by: McArti0 on 12:24, 27 February 25
Regardless of the housing version ...
Title: Re: External ez80
Post by: Sykobee (Briggsy) on 15:44, 27 February 25
Quote from: zhulien on 08:10, 27 February 25BBecause Carefully coded your same code can run on internal z80 or ez80 faster
Honestly I think a Pico could emulate a Z80 faster than an eZ80 can run.

And if you change the Pico into a task-specific accelerator (e.g., 'renderDoomScene' where all the maths and rendering to a 16KB CPC screen is done on the chip and then copied to main memory for display) it excels even more. Is this really a CPC? No, but it's been done on 8-bit console cartridges so ...
Title: Re: External ez80
Post by: McArti0 on 18:58, 27 February 25
Without solder LQFP-100 0.5mm for true ez80.

https://www.aliexpress.com/item/1005003507004873.html

Powered by SMFPacks Menu Editor Mod