References: Paul Robson's page www.robsons.org.uk/archive/members.aol.com/mk14emu/ | Karen Orton's Page techlib.com/area_50/Readers/Karen/micro.htm | MK_14 Rom listing | My notes | Scmp_Code
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Use the mouse to press the buttons below:-
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example1: XOR and store press abort 0 F 2 1 Mem C 4 Mem A A Mem E 4 Mem 5 5 Mem C 8 Mem 0 2 Mem 3 F ;now to execute abort 0 F 2 2 GO ;you should read: 0F29 FF |
abort 0F22 Term or abort 0F21 Mem C4 Mem AA Mem E4 Mem 55 Mem C8 Mem 02 Mem 3F ;now go and execute abort 0F22 G ; you should read: 0F29 FF The code assembled using rcasm or asm: 32 0f22: 33 0f22: ; load accumulator with 0xAA eor with 0x55 and store 34 0f22: c4 aa ldi 0aah 35 0f24: e4 55 xri 055h 36 0f26: 37 0f26: c8 02 st 2 (0) 38 0f28: ; return to the monitor 39 0f28: 3f xppc 3 40 0f29: 41 0f29: 42 0f29: ; next code is overwritten by result.
31 0f20: 90 00 jmp main0 32 0f22: 33 0f22: main0: 34 0f22: ; reload display pointer. 35 0f22: c4 00 LDI Disp.0 36 0f24: 31 XPAL 1 37 0f25: c4 0d LDI Disp.1 38 0f27: 35 XPAH 1 39 0f28: 40 0f28: c4 aa ldi 0aah 41 0f2a: cd 00 st @0(1) 42 0f2c: 43 0f2c: 90 f4 jmp main0 44 0f2e: 45 0f2e:
The display is at 0x0900+x where x is the digit Write the segments into the address, and latch. The MK14 keeps displaying until the next write to the display. (* This simulation does not do this yet! *) Update display() when CPU writes to the display memory The MK14 had a 4 bit binary decoder and a latch using 74LS154 mux. The display lit one digit at a time. This program uses SVG graphics and innerHTML to render the 7-segment display. It reads Memory[ 0x900 ] to Memory[ 0x909 ] at the moment.
In a web page you can either track key up and down. Difficult:- Could use the mouse. Buttons have different events to other tags. The keyboard is a 4x8 matrix sharing the display logic. When the cpu reads from the Keyboard addresses, the display decoder pulls a column low. If a key is pressed, the accumulator has a low in the apropriate bit if the key is pressed. The JavaScipt uses onmousedown() and onmouseUp() to set and reset a bit in an array called KeyPressesdA[] indexed by the button. This is consulted when the sc/mp reads the keyboard address. This is dualport Ram Buttons:- reset GO MEM Abort A 7 8 9 B 4 5 6 C 1 2 3 D term 0 F E Layout:- ----------------------------------- bit | 7 6 5 4 3 2 1 0 ----------------------------------- ra3 | 7 6 5 4 3 2 1 0 ra2 | 9 8 ra1 | Te Ab Me Go ra0 | F E D C B A http://www.javascript-coder.com/button/javascript-button-p1.phtml
This ports Paul Robson's C code. It needs the registers: ACC E status p0,p1,p2,p3 Functions: reset instructionInterpreter - See Paul Robinson - I used his code. helper functions
Only the first 12 bits of the program counter are decoded 000-1FF 512 byte SCIOS ROM Decoded by 0xxx 200-3FF ROM Shadow / Expansion RAM 400-5FF ROM Shadow / Expansion RAM 600-7FF ROM Shadow / Expansion RAM 800-87F 128 bytes I/O chip RAM Decoded by 1xx0 880-8FF I/O Ports Decoded by 1xx0 900-9FF Keyboard & Display Decoded by 1x01 A00-AFF I/O Port & RAM Shadow B00-BFF 256 bytes RAM (Extended) / VDU RAM Decoded by 1011 C00-CFF I/O Port & RAM Shadow D00-DFF Keyboard & Display Shadow E00-EFF I/O Port & RAM Shadow F00-FFF 256 bytes RAM (Standard) / VDU RAM Decoded by 1111