

So now it's time to have fun.... I want to base this board on the CoCo 3 for several reasons.
- Size
- 280 × 155.3 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 211
- Nets
- 222
- Pads
- 1,016
- Tracks, vias
- 0, 0
- Pours
- 9
- Routed
- Not yet
- KiCad
- KiCad 5 (file 20171130)
- Created
- 31 Aug 2021
- Updated
- 10 Dec 2021
Overview
Coco3 is an open-source printed circuit board by qbancoffee, from the qbancoffee/cocoplusplus repository on GitHub. It is a 2-layer board of 280 × 155.3 mm with 211 parts on 222 nets.
It is built around the 74LS367PC, 27C256-17/J and 74LS04PC, with the 74LS30PC, 74LS374PC and CD4052BM among its other parts. Its parts include 75 resistors, 60 capacitors, 12 ICs, 10 diodes and 5 transistors.
Main components
674LS367PC
PDIP-16Buffers, Drivers, Receivers, TransceiversTexas Instruments27C256-17/J
-0℃~+70℃ 256Kbit 4.5V~5.5V EPROM Parallel Port (Parallel) - Non-Volatile Memory (ROM)Microchip TechnologyNon-Volatile Memory (ROM)74LS04PC
PDIP-140℃~+70℃ 4.75V~5.25V 6 6.6mA 74LS PDIP-14 InvertersonsemiInverters74LS30PC
PDIP-140℃~+70℃ 1 1.1mA 18ns@5V,50pF、20ns@5V,50pF 2.7V 2V 4.75V~5.25V 400uA 500mV 74LS Series 8 800mV 8mA NAND Gate PDIP-14 Logic GatesTexas InstrumentsLogic Gates74LS374PC
PDIP-200ns 0℃~+70℃ 1 20ns 28ns@5V,45pF 35MHz 4.75V~5.25V 45mA 74LS Series 8 D-Type Rising Edge Tri-State PDIP-20 Flip FlopsonsemiFlip FlopsCD4052BM
SOP-16-55℃~+125℃ 15ns 2 40MHz 4:1 5V~15V 80Ω Level shifting SOP-16 Analog Switches, Multiplexers ROHSJSMSEMIAnalog Switches, Multiplexers
README
README.mdCoCo++
I spent some time transcribing the CoCo 3 schematic into KiCAD to contribute to the bit preserve project.
Using that schematic, I created a drop in replacement board which I subsequently ordered, assembled, and tested.
At this point I consider that project done and time to move on. If you are interested in the bit preserve
project here is the link.
Bit Preserve, recreating classic computer schematics
So now it's time to have fun....
I want to base this board on the CoCo 3 for several reasons.
- It's the latest real CoCo.
- I never used one in my youth.
- When people upgrade to to the GIME-X, they may want to use their otherwise unused GIME
- If used with a GIME-X then there would be a new CoCo added to the world.
To start this I stripped the CoCo 3 portion out of the bit-preserve project and created this repository so that I could make changes to the board that I would like to see. I'm making this available so that anyone can contribute ideas and expertise.
Goals
I still don't know what all of the goals are but I'll list some ideas that I've had or that others have mentioned or recommended.
- Having fun
- Mod for potential DMA
- USB keyboard
- Reduce overall size
- A different form factor
- Fit it in a polycase ZN-45
- HDMI or VGA out
- Composite out
- Surface mount components
- 12V power supply with standard barrel connector
- Replace DAC/ADC chip with equivalent circuitry
- Replace SALT chip with equivalent circuitry
Videos
Parts
211| Qty | Value | Footprint | References |
|---|---|---|---|
| 20 | .1uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C4, C12, C13, C14, C26, C28, C38, C39, C40, C41, C42, C47, C48, C50, C1001 +4 |
| 13 | 4.7K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R2, R3, R4, R5, R6, R7, R8, R11, R21, R24, R59, R61, R62 |
| 8 | .022uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C16, C17, C20, C21, C25, C36, C49, C57 |
| 6 | 10 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R28, R39, R46, R53, R68, R71 |
| 5 | coco2:FB_28L0138-10R-10 | FB5, FB6, FB8, FB9, FB10 | |
| 5 | 120 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R22, R43, R50, R57, R72 |
| 5 | 1N4148 | Diode_SMD:D_SOD-323F | D5, D12, D1002, D1003, D1004 |
| 5 | 2SC945(NTE85) | Package_TO_SOT_THT:TO-92L_Inline | Q2, Q3, Q5, Q6, Q7 |
| 4 | 10uF 16v | Capacitor_Tantalum_SMD:CP_EIA-3216-18_Kemet-A | C2, C3, C55, C56 |
| 4 | 1800pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C18, C19, C22, C23 |
| 4 | 1K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R36, R40, R47, R54 |
| 4 | 1KF20-04 | Diode_THT:D_A-405_P10.16mm_Horizontal | D8, D9, D10, D11 |
| 4 | 39pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C10, C11, C37, C61 |
| 3 | .033uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C5, C52, C53 |
| 3 | .47uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1002, C1003, C1004 |
| 3 | 100 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R30, R34, R69 |
| 3 | 1000pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C58, C59, C68 |
| 3 | 100K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R1, R1002, R1003 |
| 3 | 10k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R12, R1001, R1008 |
| 3 | 2K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R42, R49, R56 |
| 3 | 3K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R38, R45, R52 |
| 3 | 47 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R9, R10, R64 |
| 3 | 5.1K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1004, R1005, R1006 |
| 3 | 74LS244 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | IC10, IC11, IC12 |
| 2 | 220K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R33, R35 |
| 2 | 10K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R37, R41 |
| 2 | 220uF 25V | Capacitor_SMD:CP_Elec_8x10 | C15, C63 |
| 2 | 82K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R18, R19 |
| 2 | MountingHole | MountingHole:MountingHole_3.5mm | H1, H2 |
| 2 | W65C21N6TPLG-14 | Package_LCC:PLCC-44_THT-Socket | IC4, IC5 |
| 1 | 20K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R32 |
| 1 | 1.5K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R27 |
| 1 | 1.8uH | Inductor_THT:L_Axial_L9.5mm_D4.0mm_P12.70mm_Horizontal_Fastron_SMCC | L1 |
| 1 | 100 1W | Resistor_SMD:R_2512_6332Metric_Pad1.40x3.35mm_HandSolder | R13 |
| 1 | 100K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R15 |
| 1 | 100pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C34 |
| 1 | 100uF 16V | Capacitor_SMD:CP_Elec_6.3x5.3 | C9 |
| 1 | 100uF 6.3V | Capacitor_Tantalum_SMD:CP_EIA-3528-21_Kemet-B | C27 |
| 1 | 10M | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R44 |
| 1 | 10pF-50pF | coco2:C_Rect_L7.2mm_W7.2mm_P5.00mm_FKS2_FKP2_MKS2_MKP2 | TC1 |
| 1 | 10uF NP | Capacitor_THT:C_Radial_D6.3mm_H5.0mm_P2.50mm | C24 |
| 1 | 150 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R63 |
| 1 | 150pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C64 |
| 1 | 160K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R17 |
| 1 | 1K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R48 |
| 1 | 1M | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R65 |
| 1 | 20K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R26 |
| 1 | 20M | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R1007 |
| 1 | 20pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C30 |
| 1 | 220 1W | Resistor_SMD:R_2512_6332Metric_Pad1.40x3.35mm_HandSolder | R14 |
| 1 | 27C256 | Package_DIP:DIP-28_W15.24mm_Socket | IC2 |
| 1 | 28.63636 MHz | coco2:XTAL_ECS-286.3-20-46X | X1 |
| 1 | 3.9K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R29 |
| 1 | 300K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R25 |
| 1 | 330K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R16 |
| 1 | 33pF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C60 |
| 1 | 33uH | Inductor_SMD:L_Sumida_CDMC6D28_7.25x6.5mm | L1001 |
| 1 | 39K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R31 |
| 1 | 4.7k | Resistor_THT:R_Array_SIP9 | MP2 |
| 1 | 4.7k | Resistor_THT:R_Array_SIP10 | MP1 |
| 1 | 40.2K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R20 |
| 1 | 470 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R70 |
| 1 | 4700uF 25V | Capacitor_SMD:CP_Elec_18x22 | C29 |
| 1 | 470uF 16V | Capacitor_SMD:CP_Elec_8x10 | C54 |
| 1 | 5A 40V | Diode_SMD:D_SMB | D1001 |
| 1 | 5V | TestPoint:TestPoint_Pad_3.0x3.0mm | TP1001 |
| 1 | 7.5K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R66 |
| 1 | 74LS04 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | IC15 |
| 1 | 74LS138 | Package_SO:SOP-16_3.9x9.9mm_P1.27mm | IC9 |
| 1 | 74LS30 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | IC14 |
| 1 | 74LS367 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U1 |
| 1 | 74LS374 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | IC13 |
| 1 | 82 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R23 |
| 1 | CD4052B | Package_SO:HTSSOP-16-1EP_4.4x5mm_P0.65mm_EP3x3mm | U4 |
| 1 | CVIDEO | TestPoint:TestPoint_Pad_3.0x3.0mm | TP6 |
| 1 | Cassette | coco2:CUI_SDS-50J | JK4 |
| 1 | Conn_01x04_Male | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J1002 |
| 1 | Conn_01x12_Female | Connector_PinSocket_2.54mm:PinSocket_1x12_P2.54mm_Vertical | CN4000 |
| 1 | Conn_01x16_Female | Connector_PinHeader_2.54mm:PinHeader_1x16_P2.54mm_Vertical | CN2 |
| 1 | Conn_01x18_Male | Connector_PinHeader_2.54mm:PinHeader_1x18_P2.54mm_Vertical | BREAKOUT0 |
The 182 most common of 211 parts.
Questions
How big is the Coco3 PCB?
It measures 280 × 155.3 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Coco3 use?
211 parts, built around the 74LS367PC, 27C256-17/J, 74LS04PC and 74LS30PC. 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.
Where can I download the Coco3 KiCad files?
From the qbancoffee/cocoplusplus repository on GitHub, at the commit this page was made from: the board is coco3/coco3.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Coco3 design in my own project?
Its repository states no licence, so its author keeps all rights: ask qbancoffee before reusing the design.
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