Talk:Intel 8085

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Programming software[edit]

how can we program in 8085 microprocessors.

In the good-old-days you would start with 8085 datasheet, and paper and pencil.

Today the easiest way is to use some of the many 8085 simulators/emulators available on the net.

Take a look: type "8085 emulator" on Google. 8085 emulators/simulators are still quite popular as a teaching tool, so there are many (commercial) simulators/emulators available.

Here's couple of free emulators available:

Freeware simu&assembler

Freeware simulator

Virtual 8085 —Preceding unsigned comment added by (talk) 04:24, 20 April 2011 (UTC)

And if you want to use just an assembler:

If you want to use some higher level language (eg. basic, pascal, c, java, ..) instead of assembler, someone else may give you more hints of free/cheap software.

Agreed, this should probably be separately provided in the form of a corresponding software section that provides lists of simulators and emulators for various platforms, preferably freely available stuff (open source and freeware).

BTW: the 8085 is also generally considered a spaceborne processor: —Preceding unsigned comment added by Parallelized (talkcontribs) 20:58, 28 January 2008 (UTC)

Using INTR signal[edit]

In reference to Nazli's correction "Comprehensive use of INTR requires..." which is commented "rudimentary use of INTR is possible even without an external Programmable Interrupt Controller".

I guess this refers eg. to using pullup resistors in AD0..AD7. Using this configuration, activating INTR causes the INTR recognition cycle to read FFh, which is the opcode of RST 7 instruction. So, with minimal components, you have created a system in which INTR signal is serviced as RST 7 instruction.

All this is interesting, but I fail to see if this clarification is worth the effort in short and generalized discussion of almost antique processor. Comments anyone?

I see your point - however the previous sentence:
"Use of the INTR requires an external Programmable Interrupt Controller such as an Intel 8259"
was factually incorrect. Maybe the whole discussion on interrupts needs to be abbreviated?
Nazli 05:47, 25 May 2006 (UTC)
You are right: facts are facts, and the use of "requires" is incorrect.
And reading the paragraph containing interrupts, I agree:
the discussion on interrupts should be abbreviated.
Perhaps, if we dump the references to pins, and condense the discussion
into one sentence?
All in all, I think the article is quite good.
It puts the 8085 in historical context, discusses historical facts, and
references details which have modern equivalents.
Maybe the article should be rewritten, but it isn't very long to begin with.
Omniwriter 14:52, 25 May 2006 (UTC)

Overall the article seems ok. The section on interrupts could possibly be shortened. One suggestion:

Old section:

"The microprocessor has three hardware based interrupt operations which are found in pins 7 through 9, these are called RST 7.5, RST 6.5, and RST 5.5 respectively. The 8085 has a TRAP interrupt which cannot be disabled (that is, TRAP is a Non-Maskable interrupt or NMI) and an INTR interrupt. Comprehensive use of the INTR requires an external Programmable Interrupt Controller such as an Intel 8259."

Proposed new section:

"The microprocessor has three hardware based interrupt operations as well as a TRAP interrupt which cannot be disabled (that is, a Non-Maskable interrupt or NMI) and an INTR interrupt."

Nazli 11:08, 26 May 2006 (UTC)

Your proposal is ok. Or how about this:
"The microprocessor has three maskable hardware interrupts (RST), one Non-Maskable hardware interrupt (TRAP), and
one externally serviced hardware interrupt (INTR)."
BTW, the articles on Non-Maskable Interrupts and 8259 are a way longer than this on 8085.
So, maybe this article could be longer and contain more details?
There are no details on opcodes of 8085.. What other aspects of 8085 are still missing?
Omniwriter 20:52, 26 May 2006 (UTC)

Clock Frequency[edit]

"The 8085 runs on a 6.14 MHz crystal, connected to X1 and X2 (pins 1 and 2)"

This is not strictly necessary is it? Only the max frequency is 6.14 MHz I believe? --Gingerjoos 03:35, 17 December 2006 (UTC)

CPU Architecture[edit]

The 8085 Architecture follows the von Neumann architecture, with a 16bit address bus, and a 8bit data bus. But it is actually based on harvard concept This abruptly ending sentence is confusing. What makes it based on Harvard-concept? Svofski 07:05, 9 July 2007 (UTC)

The simple answer is that it is not a Harvard architecture, that claim is wrong. The program memory and the working memory share the same address space and word size. It is a von Neuman machine. Contrast this with a PIC microcontroller, which is a Harvard machine. --AJim (talk) 02:33, 1 July 2013 (UTC)

Commercial 8085 Simulators[edit]

I didn't add commercial/shareware simulators, because doing so might be disputable and be considered advertising, however maybe some folks are still interested, thus I put it here:



extending 8085's memory[edit]

Can 8085's memory be extended from 64K to 16MB? —Preceding unsigned comment added by (talk) 20:34, 7 April 2009 (UTC)

  • The chip can only directly address 16 bits (64K). You could use a bank-switching scheme in external hardware to extend this, but you can do that with pretty much any CPU. Kaleja (talk) 22:30, 1 November 2011 (UTC)
    • I had the misfortune to use a Northern Telecom 585 computer which used an 8085 and bank switching to manage 1 megabyte of memory, and which supported a half-dozen users at a time. In retrospect, this was a Bad Thing and NT should have used a 68000 or a 80286 or something else instead - the machine was a dinosaur, with 8 inch hard drives storing 20 megabytes each. The CPU that once served the entire stores inventory system of a steel mill is now living a life of quiet retirement as the brains in my EPROM burner. --Wtshymanski (talk) 14:13, 2 November 2011 (UTC)

expansion of terms in microprocessor 8085[edit]

expansion of terms in microprocessor 8085 eg:SIM,RIM,OLE —Preceding unsigned comment added by (talk) 16:33, 16 April 2010 (UTC)

Useless Google Books[edit]

I thought the usual 5 minutes with Google Books would turn up a half-dozen high-quality references for this article. I've never seen so many illiterate texts before in my life! If you flip between a half-dozen pages in 45 seconds and find a spelling or grammar error every time your eye lands on a page, there's a severe problem. Evidently the editorial standards to get an 8085 textbook published are very low...not that this doesn't stop Google Books from scanning them all in. Think I'll apply to some of these publishing houses...looks like they'll print any old thing, no questions asked. --Wtshymanski (talk) 13:28, 7 July 2010 (UTC)

extended instructions[edit]

Long ago, in the 1970's, when I was building some new industrial products that incorporated the 8085, I came across an article in, as I remember, Electronics magazine, which described a small set, a half dozen or so, of undocumented op codes that the authors had discovered. I do not have a reference for the article at present. After I studied these new op codes, I became quite excited, because they were very useful extensions of the instruction set, with for instance, really useful indexing capabilities. These new instructions were far more useful that the horde of new op codes introduced with the Z80, most of which made code simultaneously longer and slower if used; we avoided all but a couple of the Zilog opcodes, even when the target machine was a Z80 and not an 8080. I asked management if I could use these 8085 op codes, the decision was not to. Our inquiry, through the grapevine, was that Intel, for marketing reasons, disowned them, because they were not compatible with the upcoming 8086/88, for which they had bright hopes, correctly as we see now. Anyway, anyone interested in the 8085 today, especially in an emulator, could benefit from these extensions. --AJim (talk) 18:43, 25 March 2013 (UTC)

Release date ?[edit]

In article there's written that the Intel 8085 was introduced in 1977. On the image there's 1976 written. Is it ok? --Filipadamer (talk) 16:57, 21 May 2013 (UTC)

The 1976 is the publishing date for copyright purposes. It is quite possible that pre production samples of the chip were released in 1976 (hence the date on the chip) even though the production chips were introduced in 1977. (talk) 13:12, 7 March 2014 (UTC)