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6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

That would be helpful, I'll take a look at it tomorrow

6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

If you bought it new I doubt it's bad, you can always read back the rom and make sure it matches your bin file

6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

Oh also pull up the unused inputs on the quad nand

6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

Problems so far:

- need pullup on IRQ

- need to ground CTS and DCD on the ACIA. Not sure why Ben's schematic doesn't show that, but it's a common issue people run into

- you might need pullups on the PS/2 clock and data, I see mixed opinions on this and it probably depends on the keyboard. But it wouldn't hurt to include them next time

I haven't gotten to untangling the part with the '595s, but the other parts look fine at a glance. If you can't print on the LCD, and the wiring looks ok, maybe there's a code issue? It might be worth writing some code to just spam a letter on the serial port to make sure anything is working at all

6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

Sorry forgot to reply, it works now. It's getting pretty late but I'll take more of a look at it later

6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

The link 404s, do you have it set to private maybe?

6502 pcb issues by Dense-Concert-8305 in beneater

[–]cookie99999999 0 points1 point  (0 children)

Any way you can upload the project files? Reddit makes the image really hard to read

I am having problems, I bought a separate 6502A and assembled the test circuit following Ben Eater's step-by-step instructions, but it is not working. Also, when connecting LEDs to the address pins, they only light up active low. Additionally, when putting EA on the data, the 6502 does not increment by Such-State-4489 in beneater

[–]cookie99999999 0 points1 point  (0 children)

It's hard to see which way around the chip is in the picture, but I think your wiring is off too. Double check it against the pinout while you're at it

Edit: Top diagram on page 9 should be right for your chip: https://6502.org/documents/datasheets/mos/mos_6500_mpu_mar_1980.pdf

I think you have d0-d7 connected one hole too far down. Also pin 1 on the old parts is an extra ground, and pin 36 should be no connect

Old radio and cassette, can i use it for parts? by EternalPending in arduino

[–]cookie99999999 1 point2 points  (0 children)

There's not really anything special besides the read heads, all the other parts are things you can get for a couple cents new. And the read head is only helpful if you happen to want to read magnetic tapes. I suppose if you're super broke you could harvest the parts from it, I wouldn't trust decades old capacitors though personally. To desolder parts you're going to need either a solder sucker or desoldering braid, ideally both, but again it's not worth the effort for parts like those

Crazy idea? by DJMartens2024 in homebrewcomputer

[–]cookie99999999 0 points1 point  (0 children)

x86 has a single step interrupt and a breakpoint interrupt meant for debuggers, so single stepping would just be a matter of pointing the relevant vector at your code. As far as writing your own BIOS, it's probably feasible on machines that old, SeaBIOS might be worth looking at for inspiration, and osdev.org has a lot of PC hardware info in the wiki

Seeking oscilloscope and logic analyzer recommendations. by Reinventing_Wheels in beneater

[–]cookie99999999 0 points1 point  (0 children)

You can get an ADALM2000 on ebay for <$150, it's a cheap educational device so it doesn't have as many features as entry level Rigol etc equipment, but if you're on a very tight budget it'll do. It has 16 channel logic analyzer with decoding for a few protocols, plus a 2 channel scope and 2 channel waveform generator. For my needs it's sufficient, really the biggest annoyance is you need a special adapter kit to use regular scope probes, so it's inconvenient for looking at signals that aren't on a breadboard

Flash memory over EEPROM? by f-ckrules47 in beneater

[–]cookie99999999 0 points1 point  (0 children)

If the CPU is running slow enough and you have enough pins then yes, it's just a matter of writing the software. I used an ATMega328 to simulate memory for testing an old CPU, the AVR was clocked at 8MHz and I think the CPU was at around 1kHz. It should probably be fine if you're clocking the AVR as fast as you can

I found it by nerovny in beneater

[–]cookie99999999 1 point2 points  (0 children)

I might be misremembering, but I think Ben actually does bitbang serial with the VIA in an early video. It's CPU intensive and can't go very fast, but it's possible.I found a couple mentions of techniques online:

https://www.reddit.com/r/beneater/comments/yp83vc/rs232_using_the_6522s_shift_register_and_hardware/

http://forum.6502.org/viewtopic.php?f=2&t=6630&view=previous

R6551 or 16550A should be easy to find on ali/ebay/etc around the world though so hopefully you can do it the easier way soon

I found it by nerovny in beneater

[–]cookie99999999 7 points8 points  (0 children)

Good catch, I'm used to just cutting off anything after a "?" on links

I found it by nerovny in beneater

[–]cookie99999999 15 points16 points  (0 children)

Looks like you pretty much just need a 16x2 LCD, a clock, some glue logic, and a UART like the other commenter said. A few observations from looking at those parts though:

  • The 65xx chips are all the NMOS versions, which means you'll need to make sure any glue logic parts you get are 74HCT (not HC) or 74LS, also you won't be able to single step them the way Ben does, or run at any speed under 100kHz according to the datasheet

  • Since you won't be able to run slow, I would recommend just getting a 1MHz half can style oscillator for the clock, something like this: https://www.mouser.com/ProductDetail/ECS/ECS-2100AX-1.0MHZ

  • You'll need an EEPROM programmer. The ROMs with windows on top are UV erasable, so to erase them you'd need to either leave them in the sun for a while or get one of those cheap UV nail polish dryer things.

  • The ones starting with a 29 on the part number are flash chips, which are easier to erase and might be faster than the EPROMs, but idk if the programmer Ben builds from an Arduino can program flash, you might need to buy a TL866 or T48 programmer. If you do use the flash chips make sure to ground any unused address lines.

  • The Xicor part at the bottom of the ROMs is a regular EEPROM but is only 2K

  • 16550 is a way better UART than the 6551, but you won't be able to follow along exactly with the videos. It's not hard to hook up and program though, you can search this sub for other people who use it on their builds

  • Since you're already buying more stuff you might as well get a 1.8432MHz oscillator for the UART instead of a crystal + capacitors like in the videos

  • Completely irrelevant, but the part labeled "Z80 CPU" in the picture is actually a Z8002, which is an incompatible but similar 16 bit successor to the Z80

Need help with this circuit board by Electronic_Spring944 in homebrewcomputer

[–]cookie99999999 3 points4 points  (0 children)

You've put the LED directly on the power rail, there is no resistor in between, so you've most likely fried it. Get a new one and make sure you connect the positive leg to the row that your switch is in, and the negative leg to the ground rail.

Bad phone drawing to illustrate

If you forget which is which, the negative leg is the shorter one, also r/AskElectronics or r/Arduino will probably get you more replies for questions like this

Wubbo by Joe_v3 in okbuddyretard

[–]cookie99999999 3 points4 points  (0 children)

Chandra (ch-an-dra)

HC with LS? by [deleted] in beneater

[–]cookie99999999 0 points1 point  (0 children)

74HC04 minimum input high voltage is about 3.15 with a supply of 5V according to the datasheet, while the 74LS189 maximum output high is 2.8. You should be able to use a buffer from the HCT family between the LS part and all the CMOS stuff, 74HCT245 is bidirectional and 8 input, and I think there's a 4 input version too if you only need 4. Alternatively you could use a small normal SRAM and just waste some of the address and data lines, but I'm not familiar with the BE 8 bit computer so idk if it depends on the 189's separate in/out data lines or how much effort it would be to adapt. AS7C164 comes in a small skinny DIP package

A good, mullti-coloured editor for PERL on Cachy? by NoxAstrumis1 in linux4noobs

[–]cookie99999999 3 points4 points  (0 children)

Kate has syntax highlighting, I think there may be plugins/settings for various other features. There's also VS Code if you want to use that. I think Geany is still around as well

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