Questions tagged [8080]

For questions about the Intel 8080 8-bit microprocessor

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44
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2answers
10k views

How did the Z80 instruction set differ from the 8080?

The Zilog Z80 microprocessor, known for its use in the ZX Spectrum, was designed to be a backwards-compatible extension to the Intel 8080 processor. It introduced several new instructions to the 8080'...
21
votes
2answers
5k views

The start of x86: Intel 8080 vs Intel 8086?

Why is it said that all modern Intel processors of the x86 family are said to descent from the Intel 8086 and not the Intel 8080? From the Wikipedia article on the Intel 8086, The 8086 gave rise to ...
23
votes
4answers
5k views

Why did Pokémon Red have so many overflow bugs?

(This question also applies to other Game Boy games, but Pokémon seems to be one of the best-documented.) Pokémon Red & Blue (Red & Green in Japan) is a pair of Game Boy games about capturing ...
19
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4answers
3k views

How did integer multiplication work in 8-bit BASIC without CPU support

I've recently been teaching my 11 year old binary multiplication, which is on the UK maths syllabus at secondary school. We have used long multiplication, eg shift and add. This has made me wonder ...
28
votes
1answer
3k views

What is the relative code density of 8-bit microprocessors?

When RAM is at a premium, as it was in the old days, a greater code density of an instruction set can be a substantial advantage. (Click saver: Code density refers loosely to how many microprocessor ...
21
votes
9answers
5k views

Intel 8080-based home computers

I'd like to build an FPGA replica of a home computer based on the Intel 8080. I am not looking to design my own computer, since I would like to tap into an existing software base. Were there any ...
6
votes
2answers
1k views

How does Game Boy / Sharp LR35902 HRAM work?

The Nintendo Game Boy has RAM called "HRAM" (meaning "high ram") decoded at locations $ff80 through $fffe. (All other decoded locations in the $ffxx page appear to be I/O device and system control ...
6
votes
0answers
725 views

Why is the original Altair BASIC (for the 8080 CPU) source code not available on-line?

As described by The Register in 2001, around 1987 journalists and others started asking Bill Gates for a copy of the source code for the original version of Altair (eventually Micro-Soft) BASIC, ...
11
votes
1answer
724 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 ...