Lesson H8- Hello World on the Sega Master System and GameGear

The Master System & GameGear are virtually the same hardware!
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akuyou
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Re: Lesson H8- Hello World on the Sega Master System and GameGear

Post by akuyou » Sat Jun 04, 2022 9:07 pm

There isn't one, I never read back from VRAM.
Getting a char from the screen like that may work on the SMS, but won't on a bitmap screen like the CPC, so If I need to know what's onscreen I store it in memory somewhere else so I have a solution that is portable across systems.

If you want to do it, You would need to change the VRAM select commands, theres and "or &40" command (or equivalent) which sets the port up for writing, you'd need to remove that and you then should be able to read back from the selected VRAM address
Chibi Akuma(s) Comedy-Horror 8-bit Bullet Hell shooter! // 「チビ悪魔」可笑しいゴシックSTG ! // Work in Progress: ChibiAliens

Interested in CPU's :Z80,6502,68000,6809,ARM,8086,RISC-V
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Lee
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Re: Lesson H8- Hello World on the Sega Master System and GameGear

Post by Lee » Sat Jun 04, 2022 10:06 pm

I will try it. It is for checking if the player sprite is colliding with a building or a platform which are
background tiles. This should be quicker than keeping a copy of the screen in the 8K RAM because it is using the hardware. Do you also have a tool to make the correct cartridge checksum in the code footer? I don't know anything about how amstrad screens work because Sega consoles (master system console) are famous and amstrad GX4000 is not. Interestingly the Megadrive is today a commercially viable console and
a new version of it the Megadrive mini 2 announced 2 days ago will be sold.

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Re: Lesson H8- Hello World on the Sega Master System and GameGear

Post by akuyou » Sun Jun 05, 2022 7:31 am

I never mentioned the GX4000 - but it's clearly famous enough for you to have heard of it.

Oh, and I knew precisely one person with a SMS in the UK in my lifetime, there were four with CPC computers in my street when I was growing up - popularity varies by country you know!

I cover checksums here:
https://www.chibiakumas.com/z80/helloworld.php#LessonH8

Those famicom mini/megadrive mini etc are just cheap FPGA junk quickly produced to cash in on nostalgia - you might as well 3d print a genesis case and stick your Raspberry Pi in it - it would be about as much a 'real megadrive'
Chibi Akuma(s) Comedy-Horror 8-bit Bullet Hell shooter! // 「チビ悪魔」可笑しいゴシックSTG ! // Work in Progress: ChibiAliens

Interested in CPU's :Z80,6502,68000,6809,ARM,8086,RISC-V
Learning: 65816,ARM,8086,6809

Lee
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Re: Lesson H8- Hello World on the Sega Master System and GameGear

Post by Lee » Mon Jun 06, 2022 5:59 pm

You can get different new versions of the megadrive different from FPGA you mention and the version I was thinking of was the genesis on a chip version with a cartridge slot that plays megadrive or genesis cartridges this means it has
all the circuitry of the original megadrive shrinked inside a dedicated ASIC chip whch I suspect is because patents expire after 20 years so different companies can use the valuable design for free. For example as reddit mentions

https://www.reddit.com/r/SEGAGENESIS/co ... 6_genesis/

the HG806 is a genuine gensis on a chip.

The megadrive also contains the master system circuit which need a slot shape convertor to play 8bit games so the master system is still made today.

Lee
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Re: Lesson H8- Hello World on the Sega Master System and GameGear

Post by Lee » Mon Jun 20, 2022 3:43 am

In lesson S10 for the Sega master system https://www.chibiakumas.com/z80/simplesamples.php
I did your draw smiley tile on the sega master system which I got it to work but how do change the smiley tile priority so it appears over any hardware sprite and not below it?Where to toggle the priority bit?

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