C64 PLA Replacement

INTRODUCTION Troubleshooting a dead C64 often reveals a faulty PLA IC as the root cause. The PLA does the address decoding and bank switching. SIGNETICS 82S100 (later PHILIPS PLS100) Bipolar Programmable Logic Arrays were used in early revisions of the C64 Mainboard assy, which were then replaced by MOS 8700-001 and MOS 906114-01. This blog… Read more C64 PLA Replacement

C64 MOS 8701 Replacement

INTRODUCTION The C64 can only work properly with stable clocking. In a C64 II the MOS 8701 IC generates two major clocks and maintains the fixed frequency and phase relationship. COLOR_CLK is the main crystal oscillator clock and DOT_CLOCK is derived thereof. This blog presents a replacement circuit for the MOS 8701 IC. Orginal MOS… Read more C64 MOS 8701 Replacement

Digital Debouncer

INTRODUCTION Push buttons switches are commonly used input devices. It takes some effort to filter out the glitches caused by contact bouncing in order to get a steady signal. Especially if the switch is a Single Pole Single Throw (SPST) kind of type. This blog describes a digital filter which will eliminate any glitches from… Read more Digital Debouncer

PLD Literature

Worth a read 1986 National Semiconductor „Programmable Logic Design Guide“Programmable Logic Basics 1988 SGS-Thomson Microelectronics „Programmable Logic Manual“ (GAL PRODUCTS)Technology And Technical Overview (EECMOS Cell, Latch-up, etc.) Digital Design Using ABELby David Pellerin and Michael Holley Practical Programmable Circuitsby James D. Broesch Digital Devices and Systems with PLD Applicationsby Michael A. Miller