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s3lph 2022-02-07 09:48:40 +01:00
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README.md
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@ -26,9 +26,9 @@ patterns.
* Install the [xa65][xa65] toolchain.
* Clone this repository.
* Run `make`. This will produce (among other) the following files:
* `memtest-f000.901465.bin`: The binary you'll later flash to an ((E)E)PROM.
* `memtest-f000.901465+ascii.bin`: The same code, but text is rendered as ASCII instead of PETSCII. Used by the emulator.
* `emu6502`: A MOS 6502 emulator for testing.
* `memtest*k-f000.901465.bin`: 4K, 8K, 16K and 32K variants of the binary you'll later flash to an ((E)E)PROM.
* `out/memtest4k-f000-ascii.emu6502.bin`: The same code, but text is rendered as ASCII instead of PETSCII. Used by the emulator.
* `out/emu6502`: A MOS 6502 emulator for testing.
## Testing in the Emulator
@ -36,7 +36,7 @@ The emulator uses [Fake6502][fake6502] to emulate the MOS 6502 CPU.
The following memory regions are mapped into the emulator's address
space, compatible with the PET 2001 / CBM 3001 memory map:
* `$0000:$0fff`: RAM with simulated failures (reduced size for faster testing)
* `$0000:$0fff`: RAM with simulated failures (4K only for faster testing)
* `$8000:$8fff`: Video buffer, printed to stdout after each instruction
* `$f000:$ffff`: The `memtest-f000.901465+ascii.bin` ROM
@ -44,9 +44,10 @@ Run `./emu6502`.
## Run on a Real PET / CBM
* Flash the `memtest-f000.901465.bin` binary to a ((E)E)PROM compatible to the MOS 901465 ROM chip.
* Figure out how much memory your device has. Choose the appropriate image (`memtest4k`, `memtest8k`, `memtest16k` or `memtest32k`).
* Flash the `memtest*k-f000.901465.bin` image to a ((E)E)PROM compatible to the MOS 901465 ROM chip.
* Most parallel ROMs of at least 4KiB should be usable, just short the excess uppermost address pins to GND and ensure pin compatibility, e.g. through an adapter PCB.
* Remove the KERNAL ROM from your PET / CBM.
* Remove the KERNAL ROM (the one mapped to `$f000:$ffff`) from your PET / CBM.
* Place the memtest ROM into the same socket.
* Power up the computer. It should immediately start testing the memory.
@ -63,6 +64,7 @@ After starting up, most of the screen will be empty.
* When all memtest passes have completed, there will be an additional `=` character left of these chars.
* When the memtest routine was interrupted by an NMI, there will be a `!` instead.
* When the screen is not cleared (filled with random characters), and the first line starts with `ZF***ZF` (`*` being other seemingly random characters), a fault in the first few bytes of the zero page were detected. Since the memtest uses this area to store its state, the test is terminated prematurely.
* The tree characters in between the two `ZF`s are, from left to right, the zeropage address byte, the value written, the value read back.
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