Sinclair | Science of Cambridge MK 14 Reproducing the Birth of Home Computing in the UK Parla. Bytes 2015 Madrid Colin Phillips : webmaster@mymk 14. co. uk Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Evolution in Sinclair Computers QL 1984 68008 ZX Spectrum 1982 Z 80 ZX 81 1981 Z 80 ZX 80 1980 Z 80 MK 14 1978 SC/MP Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
SC/MP? Intel 8080 1974 MITS Altair 1975 Motorola 6800 1974 Nat Semi SC/MP 1974 LCDS, Introkit 1976 Intel C 4004 1971 Mostek 6502 1975 Zilog Z 80 1976 Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Kim-1 1975 Parla. Bytes November 2015
National Semiconductor Introkit • Sinclair | Science of Cambridge Mk 14 Microprocessor Trainer for Engineers • Launched in 1976 • SC/MP I (PMOS based) @ 1 MHz • 512 bytes ROM, 256 bytes RAM • Designed for use with teletype • Optional keyboard + display based on calculator (new ROM) • Wire-wrap main board www. mymk 14. co. uk Parla. Bytes November 2015
The MK 14 • Sinclair / Science of Cambridge MK 14 • The very first home computer on general sale in UK • SC/MP Microprocessor clocked at 4. 43 MHz (spec to 4 MHz only!) • Max. 0. 2 MIPS performance • 256 bytes (BYTES) of RAM • 512 byte monitor programme • Tiny 9 digit calculator display • Only sold as kit – self construction • Optional RAM + I/O -> max total 640 bytes of RAM • £ 39. 95 (+VAT) !!! (£ 205 in 2015 money) • Nat Semi deal – mass production version of Introkit • 30 -50 k units produced (estimate was < 2 k) • No mass storage, unusable key board Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
The First Dodgy Sinclair Keyboard Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
My MK 14 • • Sinclair | Science of Cambridge Mk 14 Purchased in 1978 Added RAM + I/O chips Replacement keyboard Speaker driver for sound Wooden case Failed to work at first Taught me to program & solder, micro basics www. mymk 14. co. uk Parla. Bytes November 2015
The Technology Value / Worth Curve Worth New & Shiny Valuable Classic Mid-life Collectible Useless junk Time Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Buy or make? Sinclair | Science of Cambridge Mk 14 Original • Hard to find • Often in poor condition • Hard to add memory • Original design defects • Expensive Make • Higher quality • More memory • Better keyboard • Non-volatile storage • Better display? • Chance to play with hardware design • Cheaper? • Hard to do www. mymk 14. co. uk Parla. Bytes November 2015
Design Goals Original Design New Design SC/MP II clocked @ 4. 43 MHz 640 bytes RAM, monitor, I/O chip 100% compatible memory map, more memory in flexible fashion, original I/O Volatile storage only as standard All storage non-volatile Single memory map Multiple memory maps, 32 k+32 k modes for BASIC etc Unusable keyboard High quality keyboard Small display Original style display or larger display option Glue logic in TTL Glue logic in programmable device – size down, flexibility up Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Design Implementation SC/MP II INS-8154 N Brokers Original 0. 3” Agilent Keyboard Omron + laser engraving Memory Generic 512 K SRAM + FLASH Display Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk 1. 27 mm? ? ? Parla. Bytes November 2015
Glue Logic • • • Original design had 10 TTL chips for keyboard scan & driving display New design = old design + bank switching for large memory Limited number of gates required Pin count, pin count 5 V I/O -> problem Solderability - !PQFP etc Mach Altera 7000 Max ABL v. VHDL Software tools – license lifetime Configuration retention - how good is that Si. O 2? Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Memory Maps 16 different 4 K memory maps Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Memory Maps II Jumper for big / small memory model Rotary switch for image selection 14 different 64 K memory maps Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
PCB – 4 layer (3 signal + ground) Eagle On-line PCB fab Sinclair | Science of Cambridge Mk 14 Hardware add -on area www. mymk 14. co. uk Parla. Bytes November 2015
Board Assembly & Test Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Restoring an Original MK 14 • • Acquired via mymk 14. co. uk correspondence Arrived abused – complete rebuild required Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
MK 14 V 3. 0 – PIC Based Real-Time Emulator • • • PIC based real-time MK 14 emulator Simulates base-level MK 14 • 256 bytes RAM only, no RAM I/O RAM made non-volatile using on-chip EEPROM backing store Speed identical to 4 MHz MK 14 All SC/MP I/O available (F 0 -2, SA, SB, SIN, SOUT) USB serial interface to host PC for MK 14 code download or firmware upgrade Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
MK 14 V 3. 1 – AVR Based Real-Time Emulator • • AVR based real-time MK 14 emulator Simulates extended MK 14 • 2 K RAM made non-volatile using on-chip EEPROM backing store Speed identical to 4 MHz MK 14 All SC/MP I/O available (F 0 -2, SA, SB, SIN, SOUT) USB serial interface to host PC for MK 14 code download or firmware upgrade Hardware is done, but not the software Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
At the Show • • • Original & reproduction MK 14 s Nat. Semi Introkit (MK 14 based on this) PIC & AVR based MK 14 emulators Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
Future Work List • • Add VDU (32 x 16 mono) NIBL BASIC Intel Hex loader for download from PC assembler / compiler MSF / JJY / DCF 77 decode + display More original SC/MP based reproductions Finish the AVR emulator software Make AVR kits available online • Questions? Sinclair | Science of Cambridge Mk 14 www. mymk 14. co. uk Parla. Bytes November 2015
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