Following on from OmarL's comment, to the closed question, Why did the Spectrum Next choose Z80 on FPGA?:
But also, the eZ80 is not compatible with the ZX Spectrum because it uses port FE for its own purpose.
Does anyone have a reference for this?
I have found links to the ZX Spectrum's use of
0xFE for I/O, 16K / 48K ZX Spectrum Reference, but nothing for the eZ80 and its reserved use of
I did find a link to the ZX Spectrum SE Reference, which mentions the eZ80 in passing:
If you got very excited when Zilog announced the eZ80 then you should keep an eye on the development of Richard Kelsh's Sparky project. It uses its own 24-bit version of Basic, based in part on Sinclair Extended Basic. I thought I'd be the first to use Sinclair Extended Basic on genuine hardware but Garry Lancaster, designer of the ZX Spectrum +3e, beat me to it. I'm working with him to ensure Sinclair Extended Basic supports ResiDOS - the operating system of the ZXATASP IDE interface. We are also looking at the possiblity of merging aspects of the +3e and Sinclair Extended Basic.
as well as the familiar I/O use of
0xFE, but nothing regarding the port's use relating to the eZ80.
I would like to know if it is true that the eZ80 can not be used as a drop in replacement on the ZX Spectrum, due to a conflict relating to the port
Note: There may be other reasons why it can't be dropped in, but this question refers only to the