Can you test a CPU with a handful of spare parts?

Рет қаралды 395

Ай бұрын

Big thanks to www.pcbway.com for sponsoring this video. I bought a batch of 6507 microprocessors from China for another project. But do they work? How can I test them? The 6507 is well known for being used in the Atari 2600, but I don't have one, so I need to think of another way to test them.
A technique I've used before on the Commodore 64 and VIC-20 is the 'NOP Tester'. Essentially this is a ROM replacement that hardwires the data bus to 'NOP', which moves the CPU to the next address. This will cycle through every address, which can be measured.
Sure it's a quick and dirty test, and in no way comprehensive. But can I build a NOP tester and test this batch of 6507s?
Let's find out...
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Пікірлер: 8

@AndersNielsenAA Ай бұрын

Nice video! :) You resistor value worry me a bit. You should multiply them by 10 before you test any more 6507's. The databus is probably fine since you have RW tied high but I'd still put 10k in case it does something funky during powerup. The address pins should not be sourcing > 6mA - that'll let the magic smoke out if it's close already or at least burn the NMOS gate pullup. Also, remember there's no 65C07 - the 6507 will start losing register data < 10kHz. From experience the program counter is a bit more resilient than that so for the NOP test here, you might get away with it. It's a quick, cheap and easy way to test if a 6507 is likely to work but of course it won't test registers.

@TimsRetroCorner Ай бұрын

Always learning :)

@Daveyk021 Ай бұрын

...or a BackBit Chip Tester Pro

@TimsRetroCorner Ай бұрын

Sure, if you've got a spare couple of hundred bucks and don't mind waiting for transatlantic shipping ;)

@Daveyk021 Ай бұрын

@@TimsRetroCorner It even tests the 6530 and 6532 (!) chips in a Pet 4040 Floppy drive control board. I've use it to test 6504s, already. I really liked you showing the difference between the 6504 and the 6507. I thought the Atary 2600 used the 6504, now I have learned - almost, just missed it by 3 - heh heh

@TimsRetroCorner Ай бұрын

Well, I'm taking a different approach to testing the 6532.... but that's for another video!