Questions tagged [8085]
For questions about the 8085 8-bit microprocessor
11
questions
5
votes
0
answers
110
views
Netronics Explorer/85 monitor step execution
The ROM monitor of the Netronics Explorer/85 computer allows the step by step execution of a user program. This is implemented with the help of the 8155 timer and the trap interrupt line of the 8085: ...
- 153
0
votes
1
answer
118
views
Netronics Explorer 85 level A interrupt handling mechanism
I'm trying to understand how the RST 7.5 interrupt circuit works in the Explorer 85 level A, since in the i8085 the address jumped is located in 003CH (for level A there is no memory mapped here), but ...
- 153
13
votes
3
answers
554
views
How much extra die area did a CMOS CPU take?
Starting in the late seventies, the microchip industry generally switched from NMOS to CMOS, primarily because CMOS circuits use less power, though they also have other advantages like more noise ...
- 63.1k
6
votes
1
answer
642
views
Why did the 8085 multiplex data with the low address byte?
Intel’s 8085 used bus multiplexing to stuff more functionality into 40 pins than would otherwise be possible. One of those pins, ALE, signals when the AD0…7 pins are outputting the low byte of the ...
- 2,299
10
votes
2
answers
719
views
Simulating a 8085 using a Z80?
I am studying the replacement of a 8085 with a Z80 (I am aware that they are not pin-compatible, the solution is to be made in a board of new design rather than on the old board). The sole reason is ...
- 793
21
votes
3
answers
3k
views
Z80 to x86 asm translator?
8086 is source code compatible with 8080. Zilog Z80 extended Intel 8080 with:
An enhanced instruction set including bit manipulation, block move, block I/O, and byte search instructions
New IX and IY ...
- 3,764
4
votes
2
answers
483
views
Execution time for conditional jumps on the Intel 8080
On the Intel 8080, all conditional instructions have varying execution time depending on whether the condition is true or not, except conditional jumps. Why is this?
The Intel 8085 changes this; there,...
- 1,539
18
votes
1
answer
3k
views
Which undocumented 8085 instructions is Steven Morse referring to in "In The Beginning"?
In S. P. Morse's 1980 allegory, "In The Beginning", he writes
And Intel said, "Let there be an 8085 with an oscillator on the same chip as the processor, and let an on-chip system controller ...
- 3,388
3
votes
1
answer
2k
views
Carry flag in 8080/8085 subtraction
How is the carry flag set during a subtraction by the 8080 or 8085 processor?
For addition, the carry flag is set if the result is greater than 255 (i.e. if it overflows).
From the programmer's ...
- 2,005
12
votes
1
answer
1k
views
8080/8085 Instruction Test Suite
(This question was inspired by Comprehensive test suites for MOS 6520 PIA / 6522 VIA / 6526 CIA)
Is there a comprehensive test suite for the Intel 808X series of processors? Something that would ...
- 9,620
8
votes
2
answers
1k
views
Intel 8080 Read/Set Interrupt Mask Instructions
According to Intel's 8080-8085 Assembly Language Programming guide, the OP Code 20 corresponds to the Read Interrupt Mask (RIM) instruction, and 30 corresponds to the Set Interrupt Mask (SIM) ...
- 9,620