C128-z80-8mhz
About the C128-z80-8mhz PCB
C128-z80-8mhz is an open source PCB design by ytmytm, published on GitHub. It is a 2-layer board measuring 31.5 × 75.7 mm, with 11 components from 10 distinct parts.
Other key parts include the Z80CPU PINS TO SOCKET, Z80CPU, 74LS74 and GAL22V10. By type, the board carries 4 ICs, 3 jumpers, 2 resistors, 1 connector and 1 capacitor.
It belongs with the retro computing designs in this gallery.
From the project
Double the clock speed of Z80 in C128
With a simple daughterboard, a GAL and a 74LS74 the Z80 in C128 can run at dot clock frequency (almost 8MHz) during its 1MHz phase of the system clock, effectively doubling the speed.
Basic benchmarks written in Turbo Pascal show that indeed it is about twice faster.
CP/M is visibly snappier, to the point of being usable.
This circuit works fine, during tests it was stable for several hours, busy with drawing fractals and calculating pi using Monte-Carlo method.
Main components on the C128-z80-8mhz
C128-z80-8mhz bill of materials (BOM)
11 components, 10 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | Z80CPU PINS TO SOCKET | DIP-40_W15.24mm_Socket_LongPads | U1 |
| 1 | Z80CPU | DIP-40_W15.24mm_Socket_LongPads | U2 |
| 1 | 74LS74 | DIP-14_W7.62mm_Socket | U3 |
| 1 | GAL22V10 | DIP-24_W7.62mm_Socket | U4 |
| 1 | EXP_PORT | PinHeader_1x03_P2.54mm_Vertical | J2 |
| 1 | WAITPASS | PinHeader_1x02_P2.54mm_Vertical | JP1 |
| 1 | CLOCK_SEL | PinHeader_1x03_P2.54mm_Vertical | JP2 |
| 1 | FAST/SLOW | PinHeader_1x02_P2.54mm_Vertical | JP3 |
| 1 | 0.1uF | C_Disc_D8.0mm_W2.5mm_P5.00mm | C1 |
| 2 | 10K | R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R1, R2 |
C128-z80-8mhz design files
The KiCad project lives in the ytmytm/c128-z80-8mhz repository on GitHub; these links point at the commit this page was built from.
C128-z80-8mhz: common questions
How big is the C128-z80-8mhz PCB?
The C128-z80-8mhz measures 31.5 × 75.7 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the C128-z80-8mhz?
11 components, from 10 distinct parts. The full bill of materials is listed on this page.
Where can I download the C128-z80-8mhz design files?
From the ytmytm/c128-z80-8mhz repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the C128-z80-8mhz design in my own project?
The repository has no license, so all rights stay with ytmytm. Use it as a reference, and ask the author before reusing the design.
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