r/beneater
My first extremely-simple PCB
It finally arrived.
Power strips with built-in decoupling capacitors.
(Did not solder the optional electrolyte capacitors yet)
Finally, less wire-cutting for the power rails.
Soldering them actually is quite efficient. Just put the pins in the power rails first, then put the PCBs on top, then solder twenty at a time.
Only issue: my capacitors are wider than the holes.
By the way, shall I make a product out of these? I can change all components to surface mount, and I can image the result would be pretty cheap.
u/MindlessExplorer2845 — 11 days ago
SAB-8275 video circuit advice
I’m looking to build a simple system to display text received from an external source, whether it’s serial or 8 bit parallel onto a TTL input monochrome crt. The circuit came from a board with an SAB-8275 chip and a 27c64 eprom for character generation with the outputs hooked to a PISO shift register. I have a basic idea of how the 8275 works but my main questions are: how would I go about building sync and dot timing circuitry for the rest of the character generator, and if it would be easier to have it driven by a microcontroller like an esp8266, an arduino mega, or a z80 which I have a couple of. I’ve attached a picture of the board I pulled the 8275 off of if it helps
u/rivalfire5 — 11 days ago
▲ 2 r/beneater
Home brew final boss(68060)
I'm making a custom 68020 workstation OS currently. Later, I plan to move to an early Pentium-class design through the 68060 for Rev 2.
I'm currently working on Rev 1 of my motherboard, and I have a full ISA bus planned, controlled by two CPLDs with DMA an SD card interface And a 68881 FPU. My OS Will be on git hub soon its able to be simulated on MAME I’m using it as a way to get a
Clean emulation before I port it to my hardware.
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u/AcanthisittaBest4705 — 10 days ago
▲ 27 r/beneater
If you liked microcoding a breadboard computer, I made a browser version: design the machine, write the microcode, step through every tick
Hi! I've been building **ExµArch**, a computer architecture playground that runs entirely in the browser: https://www.exuarch.com
Free, no account, nothing to install, MIT licensed (source: https://github.com/olebru/exuarch).
**How it works**
- **Build the hardware.** Drag devices onto buses and wire them up: registers, an ALU, RAM, an MMU, an interrupt controller, a timer, a real time clock, a keypad, an LCD, a 640×480 framebuffer, a blitter, even a triangle rasterizer.
- **Write the microcode.** Each instruction is a list of steps, and each step is a set of control lines, like `pc.output, mem.loadmar`. The instruction set comes out of your microcode, and the assembler, completion and hover help follow from it.
- **Run it.** Step one tick at a time and watch the buses, every register, the decoder ROM and a trace, or run flat out at around 2 MHz.
**14 example machines** go from TINY-16 (one register, seven instructions) to a stack machine, a RISC, a CISC with six addressing modes, a Harvard machine, a transport-triggered machine, one with interrupts, and a small 3D GPU that spins a shaded cube. There's also WORM-16, a machine with no jumps whose program is a queue crawling round a ring memory. The newest addition is a falling blocks game that keeps time with a real time clock interrupt and draws with a blitter.
Nothing is a black box. A built-in handbook walks you from an empty canvas to a working machine, and says plainly where the simulator simplifies compared with real hardware.
It needs a computer with a keyboard; on a phone you get a short intro page instead.
I'd love feedback: what machine would you build first, and which device is missing?
u/Muttrikken — 11 days ago