A M68k Multi-Board Computer design. The design basics is as follows: 1) A backplane PCB contains the majority of the bus, such as the address and data lines. 2) Cards slot into the backplane.
VGA is an open-source printed circuit board by GeraKuznetsov, from the GeraKuznetsov/M68K-MBC repository on GitHub. It is a 2-layer board of 152.4 × 162.6 mm with 143 parts on 259 nets, routed with 3,412 tracks and 560 vias.
It is built around the HC153, 74HC245D and 74HC157D, with the 74HC161S, 74FCT374TS and 74ACT158PC among its other parts. Its parts include 47 capacitors, 47 ICs, 27 resistors, 9 diodes and 6 transistors.
A M68k Multi-Board Computer design. The design basics is as follows:
IO and CPU cards are currently completely untested, and the memory card is missing a chip to enable the card's data transmitters.
/Schematic/: The actual MBC schematics Note: LS components are sometimes used when the library has no corresponding HC part. All parts are meant to be HC, with the exception of LVC in 5v->3v translation (output to SD card) and HCT in 3v->5v translation (input from SD card). You can use ACT (or AC if you are feeling brave) but at <16Mhz there should not be a need for fast ACT/AC buffers/gluelogic, especially due to the 68k's slow bus cycles (in comparison to say a 6502 or a z80).
Schematics/BP - design for the backplane (TESTED) Schematics/CPU - design for CPU card. (NOT TESTED) Schematics/IO - design for IO card with SD card, PIO, PS2, RTC. (NOT TESTED) Schematics/MEMv2 - second version of the memory card, doesn't even have the layout done. (NOT FINISHED) Schematics/MEMv1 - first version of the memory card, missing 74HC20 and gate to enable the card bus buffers (TESTED) Schematics/Footpp - various footprints Schematics/Lib - various symbols
/Code/ WIP code, just testing stuff, will eventually be OS
/sst39f040_inBB/: Allows you to connect an arduino mega to the backplane and program the flash chips on the memory card in-circuit. TODO: document this better sst39f040_inBB/avr - the arduino mega code sst39f040_inBB/send.py - script file to send the data, requires serial lib
| Qty | Value | Footprint | References |
|---|---|---|---|
| 46 | 100nF | 68000:DIP-2_200_ELL | C1, C2, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23 +30 |
| 16 | R | 68000:res | R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16 |
| 11 | 74HC157 | 68000:DIP-16 | U1, U7, U13, U14, U15, U16, U19, U20, U21, U22, U24 |
| 9 | D | 68000:D | D1, D2, D3, D4, D5, D6, D7, D8, D9 |
| 8 | HC153 | 68000:DIP-16 | U2, U3, U8, U9, U35, U36, U37, U38 |
| 6 | 71256(32Kx8) | 68000:DIP-28 | U25, U26, U27, U28, U29, U30 |
| 6 | Q_PNP | Package_TO_SOT_THT:TO-92_Inline | Q1, Q2, Q3, Q4, Q5, Q6 |
| 5 | 74HC161 | 68000:DIP-16 | U6, U11, U12, U17, U18 |
| 4 | 1K4 | 68000:res | R17, R18, R20, R21 |
| 4 | 74FCT374 | 68000:DIP-20 | U43, U45, U46, U47 |
| 4 | 74HC245 | 68000:DIP-20 | U31, U32, U33, U34 |
| 3 | 1K3 | 68000:res | R19, R22, R27 |
| 2 | 130 | 68000:res | R23, R25 |
| 2 | 220 | 68000:res | R24, R26 |
| 2 | 2x08 | 68000:2x08 finger | J2, J4 |
| 2 | Conn_02x01 | 68000:2x01 finger | J5, J6 |
| 1 | 02x08 | 68000:2x08 finger | J3 |
| 1 | 74ACT158 | 68000:DIP-16 | U10 |
| 1 | 74ACT161 | 68000:DIP-16 | U5 |
| 1 | 74F151 | 68000:DIP-16 | U41 |
| 1 | 74HC00 | 68000:DIP-14 | U39 |
| 1 | 74HC374 | 68000:DIP-20 | U42 |
| 1 | 74HC74 | 68000:DIP-14 | U44 |
| 1 | 74LS139 | 68000:DIP-16 | U40 |
| 1 | C_Polarized_Small | Capacitor_THT:CP_Radial_D5.0mm_P2.50mm | C48 |
| 1 | DB15_Female | 68000:DSUB-15-HD_Female_Horizontal_P2.29x1.98mm_EdgePinOffset3.03mm_Housed_MountingHolesOffset4.94mm | J1 |
| 1 | R_Pot | 68000:POT | RV1 |
| 1 | SST39F040 | 68000:DIP-32_600_ELL | U23 |
| 1 | mxo45hs-8 | 68000:DIP-2x2osci | U4 |
GeraKuznetsov/M68K-MBC
A M68k Multi-Board Computer design. The design basics is as follows: 1) A backplane PCB contains the majority of the bus, such as the address and data lines. 2) Cards slot into the backplane.
GeraKuznetsov/M68K-MBC
A M68k Multi-Board Computer design. The design basics is as follows: 1) A backplane PCB contains the majority of the bus, such as the address and data lines. 2) Cards slot into the backplane.
GeraKuznetsov/M68K-MBC
A M68k Multi-Board Computer design. The design basics is as follows: 1) A backplane PCB contains the majority of the bus, such as the address and data lines. 2) Cards slot into the backplane.
GeraKuznetsov/M68K-MBC
A M68k Multi-Board Computer design. The design basics is as follows: 1) A backplane PCB contains the majority of the bus, such as the address and data lines. 2) Cards slot into the backplane.
GeraKuznetsov/M68K-MBC
A M68k Multi-Board Computer design. The design basics is as follows: 1) A backplane PCB contains the majority of the bus, such as the address and data lines. 2) Cards slot into the backplane.
slu4coder/Minimal-64x4-Home-Computer
My DIY TTL home computer with VGA and PS/2 and 4x the processing power of a Commodore C64 or Apple II.
axelo/custom-cpu
Cutom CPU built from 7400-series integrated circuits (and FLASH roms)
benanderman/spork-8
An 8-bit CPU, made with TTL chips on custom, modular PCBs. Includes board designs, and Arduino code to program its instruction set and programs.
rjw57/simplest-80s-computer
This is my rough scratch repo where I keep experiments to do with desiging 80s computer peripherals. It is not in any sensible shape to be used by others yet, apologies.
It measures 152.4 × 162.6 mm and has 2 copper layers, 1.6 mm thick.
143 parts, built around the HC153, 74HC245D, 74HC157D and 74HC161S. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
From the GeraKuznetsov/M68K-MBC repository on GitHub, at the commit this page was made from: the board is Schematics/VGA/VGA.kicad_pcb and its schematic Schematics/BP/BP.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository states no licence, so its author keeps all rights: ask GeraKuznetsov before reusing the design.
