SPeccy ON the ZeddY

[siggi]

Yes, it is solved
Thanks
Siggi

[kolbeck]

I decided to give this a go on real hardware as well, trying to avoid opening and modifying the ZX81. Only modification to my setup, which has been done long time ago - My ZX81 has internal 16K RAM upgrade (WRX compatible) and a composite mod.

I know it looks like chaos, but huuraaa - it's working - my ZX81 thinks it's a ZX Spectrum and everything needed is connected to the expansion port of the ZX81.

...and yes, there is an EEPROM in there somewhere...

[PitMakot]

Hi Zsolt

There is one 32k RAM chip in the XPACK544.png diagram.
Would it be possible to add a second RAM chip to make it more compatible with ZX Spectrum and an AY chip?
There is, for example, such a project:
https://revspace.nl/Zon_ZX-81_Programma ... ng_SD-Card
AY together with SD card.
And the basic question.
Would it be possible to run it all together in SPonZY mode?

[netuffgeb]

Hi, this project of revspace was realized by Martin and small bugs were removed by me. I also created a new PCB and add 32k RAM until a final version hardware

PSG_E16M32_V221.pdf

(221.96 KiB) Downloaded 260 times

and wrote the software. See

ZX_SPI_SD_RU8888_V501EXT.7z

(2.43 KiB) Downloaded 224 times

It is started with LET L=USR 8888. If an SD-card (max. 2GB) is inserted in FAT16 format, the software will show a list of contents etc. and it work perfect with the original ZX-81. OK so far.
Then I added to the XPACK544 (with Joystick and Sponzy) the above described card named as

PSGJS544K_V110.pdf

(253.76 KiB) Downloaded 245 times

but because the Speccy on Zeddy does need the whole 16k of ROM I do not think there is a possibility to get access to SD-card because the firmware of this does need a part of the ROM address range 2000h to 3FFFh. My software V501 does need the memory above the RT to store the file structure. After selecting the desired file it will be copied to 4000h and above until 7FFFh max, so to say max 16k. The ZX81 can only run software from 0 to 32768 (RT). So there is no possibility to merge the SD-card and sound part of PSG_E16M32 together with XPACK544.
If you have an idea how to solve this, please let me know.

[siggi]

The ZX81 can only run software from 0 to 32768 (RT). So there is no possibility to merge the SD-card and sound part of PSG_E16M32 together with XPACK544.
If you have an idea how to solve this, please let me know.

The ZX81 can also execute code at addresses 32K to 48K, if a "M1NOT" modification is done: usually an internal modification (at ULA inside the Zeddy),
except if you want to do something like that: https://www.sinclairzxworld.com/viewtop ... 049#p28049

[netuffgeb]

Thanks for this hint siggi, I have to think about it.
The main problem is that the save/load does not work with Sponzy, so I can't get my SD-code to 40000 for example.
I use the 2018 version and tried it with an amplifier between the SPeccy and the Microchip Audio Development Board and it does not work, but it is perfectly running with the Zx81plus38rev2.02.
I entered SAVE "test" and I loaded it with LOAD "test" but the screen remain black. After interrupting with SP or Shift+V+B, I received garbage or nothing and 0 OK, 0:1, but no program like I entered before for saving:
1 REM xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
10 Print "test"
Probably there is a new version available for SPeccy or I made other mistakes entering the save/load?