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robinhedwards / A8PicoCart

UnoCart on a Raspberry Pi Pico clone
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Atari 8bit ram tester as UNO_OS.ROM #17

Open goloskokovic opened 1 month ago

goloskokovic commented 1 month ago

Would it be possible to use Shoestring’s Atari 8bit ram tester instead of OS ROM? https://jammarcade.net/shoestrings-atari-8bit-ram-tester/

This RAM test is 16k rom to be burned to 27c128 and installed in the OS socket (U5) on the Atari motherboard. By renaming RAM test file to UNO_OS.ROM in A8PicoCart can we use it to find bad DRAM?

bad-ram-example

robinhedwards commented 1 month ago

From a brief scan of the code, it might work. Easiest thing to do is to try?

Regards,

Robin

goloskokovic commented 1 month ago

tried to rename file but it is ignored in root.

how do you jump here? https://github.com/robinhedwards/A8PicoCart/blob/main/source/Pico%20VSCode%20Project/a8_pico_cart/atari_cart.c#L1630

robinhedwards commented 1 month ago

Try launching an ATR file. That’s what causes the soft OS to be loaded, then a reboot should happen into the new OS

goloskokovic commented 1 month ago

when running random ATR file it starts test but freezes.

for the reference - I was able to run this test in Altirra as OS rom

goloskokovic commented 2 weeks ago

I've tried to replace osrom.h with the ram_test.rom using xxd. once I built new uf2 file it behaved just as with uno_os.rom on atr load.

Can I load osrom.h before real OS rom as it looks like they clash in RAM? Or replace it in RAM?

flashjazzcat commented 6 days ago

The loader turns off the OS ROM before loading the patched Altirra OS, and the patched OS is careful never to re-enable ROM by setting bit 0 of $D301 (PORTB). The RAM test ROM presumably assumes it's in ROM and repeatedly sets bit 0 of PORTB; this will instantly reinstate the OS ROM and cause a crash.

You'd need a special version of your RAM tester designed to run in RAM under the OS.