
15
The timing diagrams in the appendix should be consulted to determine
specifically where the instruction execution has stopped. Note that there are
at least two and sometimes three machine cycles per instruction. The 'G'
button Schmidt trigger has a gated oscillator built into it which provides the
slow step feature. When the button is pushed and held, the oscillator is
enabled and starts outputting pulses (equivalent to TPB) at approximately
two per second, the same feature could be accomplished simply by
repetitively pushing the button. The initial delay for the first pulse is caused
by the time it takes to charge C6 up to the Schmidt trigger operating point.
The 'R' button is the reset button. Depressing the button causes the
state of the Schmidt trigger to change putting a high on the reset line. All
other functions are reset by this control.
3. CONTROL CIRCUITS
M P I L
(Figure 3)
The 'M' button is the ROM monitor select control. Depressing the
button causes the D flip flop (U12) to be set. The not Q output goes low and
this signal is used to select the ROM when the first 32 locations are
addressed. (see figure 4)
The 'P' button is the memory protect control. Depressing the button
causes the D flip flop (U10) to be set. The Q output is ORed with the CPU
MWR signal. When in the Protect mode, the MWR signal is blocked and
memory write is inhibited.
The 'L' button is the load mode select control. Depressing the button
causes the D flip flop (U10) to be set. The Q output is NORed with the clear
and wait CPU controls forcing them low and putting the CPU in the wait
state.
The 'I' button is the input control. Depressing the button causes the
state of the Schmidt trigger (U21) to change to low.
This pulls the EF4 CPU sense line low. This signal can be used by a
program to detect that input data is available. Also the D flip flop (U7) is
clocked causing the DMAIN signal to go low. This signal is used by the
CPU in the 'built in' load mode to load data into memory.
Содержание SUPER ELF
Страница 1: ...SUPER ELF AN 1802 BASED MICRO COMPUTER BY QUEST COPYRIGHT 1977 BY QUEST ELECTRONICS ...
Страница 12: ...12 Hexadecimal Keyboard Figure 1 ...
Страница 14: ...14 Control Circuit G R S W Figure 2 ...
Страница 16: ...16 Control Circuit M P I L Figure 3 ...
Страница 18: ...18 ROM RAM Select Display Control Figure 4 ...
Страница 20: ...20 RAM ROM Memory Figure 5 ...
Страница 21: ...21 State Mode Display Figure 6 ...
Страница 22: ...22 Output Data Display Figure 7 ...
Страница 24: ...24 Address Buffers Latch Figure 8 ...
Страница 26: ...26 Address Display Figure 9 ...
Страница 27: ...27 Power Supply Memory Saver Figure 10 ...
Страница 28: ...28 Video Generator Clock Generator I O Port Decode Q Circuit Figure 11 ...
Страница 36: ...36 COMPONENT LAYOUT V 1 0 Figure 13 ...
Страница 37: ...37 COMPONENT LAYOUT V2 0 Figure 14 ...
Страница 38: ...38 BOARD WIRING PATTERN V1 0 FRONT Figure 15 ...
Страница 39: ...39 BOARD WIRING PATTERN V1 0 BACK Figure 16 ...
Страница 40: ...40 BOARD WIRING PATTERN V 2 0 FRONT Figure 17 ...
Страница 41: ...41 BOARD WIRING PATTERN V 2 0 BACK Figure 18 ...