ReQUAD
About the ReQUAD PCB
ReQUAD is an open source PCB design by bkw777, published on GitHub under the Custom license license. It is a 2-layer board measuring 51.3 × 18.3 mm, with 13 components from 11 distinct parts.
Other key parts include the AS6C1008-55STIN, 74HC573PW,118, SN74LVC2G79DCUR and 74HC02PW,118. By type, the board carries 4 ICs, 4 capacitors, 2 resistors, 1 connector and 1 battery holder.
From the project
A modified respin of Steven Adolph's QUAD memory expansion for the TRS-80 Model 100
Build notes, The pin 1 mark on DA1, BAV756S, is tiny and faint, but there is one, you just need a lot of magnification and light. The markings look like .A7t and the . is at pin 1. The pinout is not symmetric, and so the part must be installed in the correct orientation.
The device disables and replaces the machine's original internal 32k RAM, so copy any files off of the computer before installing the reQUAD. You won't be able to access the internal ram except by removing the reQUAD.
Main components on the ReQUAD
ReQUAD bill of materials (BOM)
13 components, 11 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | AS6C1008-55STIN AS6C1008 | TSOP32-dual | U1 |
| 1 | 74HC573PW,118 HC573 | TSSOP-20_4.4x6.5mm_P0.65mm | U2 |
| 1 | SN74LVC2G79DCUR 2G79 | VSSOP-8_2.3x2mm_P0.5mm | U3 |
| 1 | 74HC02PW,118 HC02 | TSSOP-14_4.4x5mm_P0.65mm | U4 |
| 1 | 920-0172-01 Model_100_System_BUS | DIP-40_PCB | J1 |
| 1 | Keystone 3031 Keystone_3031 | Keystone_3031 | BT1 |
| 1 | BAV756S,115 BAV756S | SOT-363 | DA1 |
| 1 | TAJC227K010RNJ 220u10v | CP_6032 | C1 |
| 3 | CL21B105KAFNNNE 1u | C_0805 | C2, C3, C4 |
| 1 | RK73B2ATTD102J 1k | R_0805 | R1 |
| 1 | RC0805FR-07470KL 470k | R_0805 | R2 |
ReQUAD design files
The KiCad project lives in the bkw777/reQUAD repository on GitHub; these links point at the commit this page was built from.
- LayoutPCB/reQUAD.kicad_pcb
- SchematicPCB/reQUAD.kicad_sch
- BOMPCB/out/reQUAD.bom.csv
ReQUAD: common questions
How big is the ReQUAD PCB?
The ReQUAD measures 51.3 × 18.3 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the ReQUAD?
13 components, from 11 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the ReQUAD design files?
From the bkw777/reQUAD repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.
Can I use the ReQUAD design in my own project?
It is published under Custom license, which limits how it may be reused; read the license before building on it.