이안은 뭐하니?

I set the TMS9918 with VRAM and configure the IO Address.

The RAM using of APPLE II one not other one.

I did load the image ROM file by PRODOS and works as below

This board doesn't have RAM so, the ROM image is on the APPLE II RAM.

It is hybrid structure unlike other H/W emulation one.

Even hardware emulation, it can't say hardware emulation cause it has same logic design of the SC3000 and TMS9918 for Video.

Seeing is believing.

Watch it :)

The Z80 run 2Mhz but, it looks not slow running game.

It doesn't have any joystick nor keyboard so, I can't play but, I could see everything without delay.

Anyway, I will move this board for the MSX1 computer.

Someday, I could show running the MSX1 system on my APPLE //e.

Also Tested CPM 3.0 works!

With several Logic update on CPLD, I got finally working softcard.

I tested it and work as 1Mhz and 2Mhz.

My target is 7Mhz Z80 card. it would be very interesting steps.

The softcard used DMA and RDY and Z80 Wait for it's purpose of CPU.

Thanks MS for the idea of Z80 working on 6502 based Computer.

Now, I'm starting to put TMS9918 VDP and trying to make it work.

I hope to show some of working screen soon.

Thanks

APPLE II using 6502 CPU and there are another 8 bits CPU Z80 is one of famous one too.

In fact, APPLE II can use both of CPU Z80 and 6502 but, It was almost forgotten technology how to applied it on APPLE II.

Hence, I started to make Z80 card and it will work as a softcard for CP/M.

Used Z80 CPU and some chips.

Major control chip will use a CPLD to act as Softcard and started wiring.

Wiring always hard job but, but have to check all of lines to make sure to avoid mistake connection.

I was took long hours and needed adjust wires to fix my mistakes.

I set chips and added some more wiring for proper emulate the Softcard.

I did research about the softcard and could learn about the DMA works and RDY and the trick of timing for Z80 CPU.

My plan is several steps,

First, I want make it run the CP/M OS.

For this I will apply some slow Mhz and try to make it run as Softcard.

I think that it is possible to make it run 1Mhz and it would be easier than other faster speed.

Then Try other faster speed.

2Mhz is original softcard and at least have to reach this speed to make feel same as what I experienced by the CP/M by softcard.

The final softcard make it run as 7Mhz..

It is the maximum possibility with softcard design I guess.

Anyway, there is a reference of 7Mhz CP/M.

http://www.applefritter.com/?q=content/z80-softcard-able-run-7mhz-faster-stock

It looks very interesting to me. but, I don't understand fully about the tricks.

Anyway, Let me see if it works.

Thanks