Zx81-external rom with display
About the Zx81-external rom with display PCB
Zx81-external rom with display is an open source PCB design by zxinfo-diy-electronics, published on GitHub. It is a 2-layer board measuring 84.2 × 53.8 mm, with 17 components from 8 distinct parts.
Other key parts include the AT28C64, 74LS374, 74LS192 and 74LS157. By type, the board carries 6 ICs, 6 capacitors, 3 diodes, 1 connector and 1 resistor.
It belongs with the displays & leds and retro computing designs in this gallery.
From the project
External ROM interface with partial display logic for ZX81
Partial display logic only, as this is what's available at the extension bus.
Will change the diode from 1N4148 to BAT85, as recommended for this type of usage.
Replace IC socket with ZIF Test socket, as it turns out that I'm swapping out EEPROMs based on needs and usage.
With this interface it is now possible to run ROMs such as the ZX.ASZMIC, Skyware Forth and even the ZX80 ROM.
Main components on the Zx81-external rom with display
Zx81-external rom with display bill of materials (BOM)
17 components, 8 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | AT28C64 | DIP-28_W15.24mm | U1 |
| 1 | 74LS374 | DIP-20_W7.62mm | U2 |
| 1 | 74LS192 | DIP-16_W7.62mm | U3 |
| 3 | 74LS157 | DIP-16_W7.62mm | U4, U5, U6 |
| 1 | Connector ZX81 | EDGE ZX81 BOTTOM | J1 |
| 3 | D | D_DO-34_SOD68_P7.62mm_Horizontal | D4, D5, D6 |
| 6 | 100nF | C_Disc_D3.0mm_W1.6mm_P2.50mm | C1, C2, C3, C4, C5, C6 |
| 1 | 10K | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R2 |
Zx81-external rom with display design files
The KiCad project lives in the zxinfo-diy-electronics/zx81-external-rom-with-display repository on GitHub; these links point at the commit this page was built from.
Zx81-external rom with display: common questions
How big is the Zx81-external rom with display PCB?
The Zx81-external rom with display measures 84.2 × 53.8 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the Zx81-external rom with display?
17 components, from 8 distinct parts. The full bill of materials is listed on this page.
Where can I download the Zx81-external rom with display design files?
From the zxinfo-diy-electronics/zx81-external-rom-with-display repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the Zx81-external rom with display design in my own project?
The repository has no license, so all rights stay with zxinfo-diy-electronics. Use it as a reference, and ask the author before reusing the design.
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