Site Index
Please scroll down to view the entire site contents. Sections are listed in alphabetical order.
Select an item from the index to be taken to that section.
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Contact Information
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Copyright Information
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Eprom Programmer
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Harlequin
- The Harlequin home page
- Prototype Summary
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CPU
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Design
- Correcting the WAIT timing
- Hooking up the Z80 and ROM
- Spectrum compatible interrupts
- A re-examination of the interrupt acknowledge
- Examining the port contention behaviour
- ULA IO Port contention tricks
- IO Specific Contention Timing
- Implementing the ULA Contention Model
- Testing the new contention model
- In depth Testing and Mega ShockDem Failure
- Memory Contention Error and Solution
- Improving Stability of MemWait
- Memory Contention Revision and the Snow Effect
- Clock, IO Read and Wait alignment re-design
- The ZX Spectrum Dynamic Memory
- Harlequin Dynamic Memory Analysis
- Harlequin Dynamic Memory Implementation
- The Harlequin Snow Effect
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Testing
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Goals
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Interfaces
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Cassette
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Design
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Testing
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Design
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Keyboard
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Design
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Testing
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Sound
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Design
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Memory
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Schematics
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Testing
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ULA Replacement
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Video
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Design
- Minimal (Cheap) Vertical Sync
- The Spectrum Display. Juggling screen bytes
- The display control signals required by the Harlequin
- The Horizontal sync and control timing design, to the PAL specification
- Adjustments to the horizontal control timing
- Horizontal sync and control implementation
- Pictures of the horizontal control and sync oscilloscope traces
- Designing the vertical sync generator
- How the horizontal sync generator helps us generate the vertical
- Calculating the vertical sync pulses
- Generating the vertical control signals
- Building the vertical sync generator
- Centering the display
- Designing the Video Memory to TV Output
- Selecting the appropriate output
- Creating Proper TV RGB Signals
- Designing the output driver and setting RGB levels
- Clock Mystery Solved
- The Video Memory Interface Design
- Redesign of the byte fetch strategy to match that of the ZX Spectrum
- A new (and correct) solution for the Vertical Reset stability
- The Spectrum FLASH attribute
- Simplifying the horizontal sync generation
- Simplifying the vertical sync generation
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Testing
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ZX Spectrum Overview
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Pictures
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Eprom Programmer
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Harlequin
- Pictures of the horizontal control and sync oscilloscope traces
- Building the vertical sync generator
- Second video test (sync), with corrected hardware and finally a picture
- First ZX Specturm loading screens displayed
- Booting the Z80 with ROM
- Testing the keyboard and interrupts
- The cassette interface
- Loading test and screen shots
- Testing the Interrupts
- Analysis of the horizontal reset glitch and interrupts
- A re-examination of the interrupt acknowledge
- The Sidewize test and Contended Memory fix
- Testing the new contention model
- Contention Test Success
- In depth Testing and Mega ShockDem Failure
- Memory Contention Error and Solution
- Improving Stability of MemWait
- Memory Contention Revision and the Snow Effect
- Clock, IO Read and Wait alignment re-design
- The ZX Spectrum Dynamic Memory
- ULA Replacement development phase 1
- The Harlequin Snow Effect
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ULA Replacement
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Software
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Spectrum
- Z80 Software
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Unpublished Games
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