4 layers161.1 × 82.9 mm
2 layers58.2 × 84.1 mm
NeoRAMremix
hackup/NeoRAMremix41A remix of the NeoRAM catridge for the Commodore 64.
- Size
- 58.2 × 84.1 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 29
- Nets
- 54
- Pads
- 286
- Tracks, vias
- 1,183, 77
- Routed
- Yes
- KiCad
- KiCad 5 (file 20171130)
- Created
- 28 Apr 2019
- Updated
- 8 Mar 2020
Overview
NeoRAMremix is an open-source printed circuit board by hackup, from the hackup/NeoRAMremix repository on GitHub. It is a 2-layer board of 58.2 × 84.1 mm with 29 parts on 54 nets, routed with 1,183 tracks and 77 vias.
It is built around the 74HCT138D, 74HCT174D and 74HCT273D, with the CR2032 among its other parts. Its parts include 5 capacitors, 4 ICs, 3 resistors, 2 diodes and 1 transistor. It belongs with the retro computing and games boards of this library.
Main components
4
74HCT138D
SO-16-40℃~+125℃ 160uA 20ns@4.5V,50pF 3/8 4.5V~5.5V 4mA 4mA 74HCT Decoder Single Supply SOIC-16 Signal Switches, Multiplexers, Decoders ROHSNexperiaSignal Switches / Encoders & Decoders / Multiplexers74HCT174D
SO-16-40℃~+125℃ 1 3.5pF 35ns@4.5V,50pF 4.5V~5.5V 4mA 5.2mA 6 69MHz 74HCT Series 8uA D-Type Reset Rising Edge SO-16 Flip Flops ROHSNexperiaFlip Flops
74HCT273D
SOIC-20-300mil-40℃~+125℃ 12ns 3.5pF 30ns@4.5V,50pF 36MHz 3ns 4.5V~5.5V 4mA 5.2mA 74HCT Series 8 8uA D-Type Reset Rising Edge SOIC-20-300mil Flip Flops ROHSNexperiaFlip Flops
CR2032
-- Unclassified goods ROHSMaxellUncategorised
README
README.mdNeoRAM Remix
The NeoRAM is a RAM extension for the Commodore 64/128 computers that is compatible with the GeoRAM modules. It features up to 2MB of RAM and it is battery buffered. A single CR2032 cell will usually preserve the data stored in the NeoRAM for several months.
The "remix" version is based on the original NeoRAM developed by Nicolas Welte in 2006. Without further consent, both the original and the remix version are licensed for personal and non-commercial use only (see details below). There is also no warranty whatsoever. USE AT YOUR OWN RISK!.
Configurations
The NeoRAM can be assembled in different configurations. By default, the PCB is configured for 2MB of RAM and battery buffering. There is no need to change any of the solder jumpers if the board is assembled completely.
If you choose to fit fewer RAM chips their respective decoupling caps can be omitted as well. The solder jumpers SJ3 and SJ4 on the backside of the PCB have to be changed to reflect the memory configuration:
| RAM | SJ3 | SJ4 | ICs | Caps |
|---|---|---|---|---|
| 2MB | 1-2 | 1-2 | U1-U4 | C2-C5 |
| 1MB | 1-2 | 2-3 | U1-U2 | C2-C3 |
| 512kB | 2-3 | 2-3 | U1 | C2 |
If you decide you don't need the battery buffering, the following components can be omitted: BT1, D1, C1, R1-3, Q1. If you skip these components you need to close the solder jumper SJ5 on the back of the PCB. Also note that D2 is still required.
See the NeoRAM Remix blog post for more details and the bill of materials.
License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Parts
29| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | 100n | Capacitors_THT:C_Disc_D4.3mm_W1.9mm_P5.00mm | C2, C3, C4, C5 |
| 4 | HM628512BFP-5 | NeoRAMremix:SO32_FP32D_20.45x11.3mm_Pitch1.27mm | U1, U2, U3, U4 |
| 4 | SolderJumper_3_Bridged12 | NeoRAMremix:SolderJumper-3_P1.3mm_Bridged12 | SJ1, SJ2, SJ3, SJ4 |
| 2 | 1N5817 | Diodes_THT:D_DO-41_SOD81_P5.08mm_Vertical_KathodeUp | D1, D2 |
| 2 | 74HCT138 | Housings_DIP:DIP-16_W7.62mm | V1, V2 |
| 1 | 10uF | Capacitors_THT:CP_Radial_D5.0mm_P2.00mm | C1 |
| 1 | 1k | Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P2.54mm_Vertical | R2 |
| 1 | 20k | Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P2.54mm_Vertical | R3 |
| 1 | 2N3904 | TO_SOT_Packages_THT:TO-92_Molded_Narrow | Q1 |
| 1 | 4k7 | Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P2.54mm_Vertical | R1 |
| 1 | 74HCT174 | Housings_DIP:DIP-16_W7.62mm | V3 |
| 1 | 74HCT273 | Housings_DIP:DIP-20_W7.62mm | V4 |
| 1 | C64-Exp-Port | NeoRAMremix:C64-Cart-NoSilkS | P1 |
| 1 | CR2032 | hackup:Battery-Holder-CR2032 | BT1 |
| 1 | LOGO | Logo:bigby2 | G*** |
| 1 | MountingHole | Mounting_Holes:MountingHole_5mm | H1 |
| 1 | Reset | Buttons_Switches_THT:SW_Tactile_SPST_Angled_PTS645Vx83-2LFS | SW1 |
| 1 | no_battery | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | SJ5 |
Questions
How big is the NeoRAMremix PCB?
It measures 58.2 × 84.1 mm and has 2 copper layers, 1.6 mm thick.
What parts does the NeoRAMremix use?
29 parts, built around the 74HCT138D, 74HCT174D, 74HCT273D and CR2032. 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 NeoRAMremix KiCad files?
From the hackup/NeoRAMremix repository on GitHub, at the commit this page was made from: the board is NeoRAMremix.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the NeoRAMremix design in my own project?
Its repository states no licence, so its author keeps all rights: ask hackup before reusing the design.
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