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2 layers280 × 155.3 mmCoco3, the printed circuit board in 3D

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

6

README

README.md

CoCo++

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
QtyValueFootprintReferences
20.1uFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC1, C4, C12, C13, C14, C26, C28, C38, C39, C40, C41, C42, C47, C48, C50, C1001 +4
134.7KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR2, R3, R4, R5, R6, R7, R8, R11, R21, R24, R59, R61, R62
8.022uFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC16, C17, C20, C21, C25, C36, C49, C57
610Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR28, R39, R46, R53, R68, R71
5 coco2:FB_28L0138-10R-10FB5, FB6, FB8, FB9, FB10
5 120Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR22, R43, R50, R57, R72
51N4148Diode_SMD:D_SOD-323FD5, D12, D1002, D1003, D1004
52SC945(NTE85)Package_TO_SOT_THT:TO-92L_InlineQ2, Q3, Q5, Q6, Q7
410uF 16vCapacitor_Tantalum_SMD:CP_EIA-3216-18_Kemet-AC2, C3, C55, C56
41800pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC18, C19, C22, C23
41KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR36, R40, R47, R54
41KF20-04Diode_THT:D_A-405_P10.16mm_HorizontalD8, D9, D10, D11
439pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC10, C11, C37, C61
3.033uFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC5, C52, C53
3.47uFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC1002, C1003, C1004
3100Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR30, R34, R69
31000pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC58, C59, C68
3100KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR1, R1002, R1003
310kResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR12, R1001, R1008
32KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR42, R49, R56
33KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR38, R45, R52
347Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR9, R10, R64
35.1KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR1004, R1005, R1006
374LS244Package_SO:SOIC-20W_7.5x12.8mm_P1.27mmIC10, IC11, IC12
2 220KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR33, R35
210KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR37, R41
2220uF 25VCapacitor_SMD:CP_Elec_8x10C15, C63
282KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR18, R19
2MountingHoleMountingHole:MountingHole_3.5mmH1, H2
2W65C21N6TPLG-14Package_LCC:PLCC-44_THT-SocketIC4, IC5
1 20KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR32
11.5KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR27
11.8uHInductor_THT:L_Axial_L9.5mm_D4.0mm_P12.70mm_Horizontal_Fastron_SMCCL1
1100 1WResistor_SMD:R_2512_6332Metric_Pad1.40x3.35mm_HandSolderR13
1100KResistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolderR15
1100pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC34
1100uF 16VCapacitor_SMD:CP_Elec_6.3x5.3C9
1100uF 6.3VCapacitor_Tantalum_SMD:CP_EIA-3528-21_Kemet-BC27
110MResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR44
110pF-50pFcoco2:C_Rect_L7.2mm_W7.2mm_P5.00mm_FKS2_FKP2_MKS2_MKP2TC1
110uF NPCapacitor_THT:C_Radial_D6.3mm_H5.0mm_P2.50mmC24
1150Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR63
1150pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC64
1160KResistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolderR17
11KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR48
11MResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR65
120KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR26
120MResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR1007
120pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC30
1220 1WResistor_SMD:R_2512_6332Metric_Pad1.40x3.35mm_HandSolderR14
127C256Package_DIP:DIP-28_W15.24mm_SocketIC2
128.63636 MHzcoco2:XTAL_ECS-286.3-20-46XX1
13.9KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR29
1300KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR25
1330KResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR16
133pFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC60
133uHInductor_SMD:L_Sumida_CDMC6D28_7.25x6.5mmL1001
139KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR31
14.7kResistor_THT:R_Array_SIP9MP2
14.7kResistor_THT:R_Array_SIP10MP1
140.2KResistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolderR20
1470Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR70
14700uF 25VCapacitor_SMD:CP_Elec_18x22C29
1470uF 16VCapacitor_SMD:CP_Elec_8x10C54
15A 40VDiode_SMD:D_SMBD1001
15VTestPoint:TestPoint_Pad_3.0x3.0mmTP1001
17.5KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR66
174LS04Package_SO:SOIC-14_3.9x8.7mm_P1.27mmIC15
174LS138Package_SO:SOP-16_3.9x9.9mm_P1.27mmIC9
174LS30Package_SO:SOIC-14_3.9x8.7mm_P1.27mmIC14
174LS367Package_SO:SOIC-16_3.9x9.9mm_P1.27mmU1
174LS374Package_SO:SOIC-20W_7.5x12.8mm_P1.27mmIC13
182Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR23
1CD4052BPackage_SO:HTSSOP-16-1EP_4.4x5mm_P0.65mm_EP3x3mmU4
1CVIDEOTestPoint:TestPoint_Pad_3.0x3.0mmTP6
1Cassettecoco2:CUI_SDS-50JJK4
1Conn_01x04_MaleConnector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_VerticalJ1002
1Conn_01x12_FemaleConnector_PinSocket_2.54mm:PinSocket_1x12_P2.54mm_VerticalCN4000
1Conn_01x16_FemaleConnector_PinHeader_2.54mm:PinHeader_1x16_P2.54mm_VerticalCN2
1Conn_01x18_MaleConnector_PinHeader_2.54mm:PinHeader_1x18_P2.54mm_VerticalBREAKOUT0

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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