All Questions

Filter by
Sorted by
Tagged with
12
votes
0answers
114 views

Uninstalling OS/400 by deleting one program

This is about the AS/400 which is an IBM mini-computer launched in 1988. It lives on today after several name changes and considerable hardware and software changes. It is still often informally ...
0
votes
0answers
34 views

Fixing aspect ratioon HDMI TV connected to a laptop when playing an old game [closed]

Not sure if this is the correct place for this question. If not, kindly point me to the correct forum. I am trying to play old games on my laptop, which is connected via HDMI to my TV. Each time the ...
5
votes
1answer
518 views

Were any vacuum tube computers built with wire wrap?

I'm trying to gain some understanding of how early computers were built; as discussed in What accounted for the cost of ENIAC? the cost of first-generation computers was not necessarily mostly about ...
10
votes
2answers
516 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
votes
1answer
81 views

Is there some simple way to avoid the artifact of “invisible” or “stuck” animation in old video games when streaming video?

I watch many live video + audio streams of people playing old video games, such as NES ones. An extremely recurring annoyance is that, for example, when the main character is damaged and is supposed ...
5
votes
1answer
202 views

Did other computer companies need to license Fortran from IBM?

Reading a fascinating online book about the history of computing, I came across this passage on http://ds-wordpress.haverford.edu/bitbybit/bit-by-bit-contents/chapter-seven/7-5-assembly-language-...
4
votes
1answer
399 views

Why ASCII paper tape has lower bit punched from the narrow side?

ASCII was presented on paper tape where the lower 5 bits cross sprocket holes as following While FIELDATA chose the other way I found placing the higher, flag bits at the narrow side appealing, ...
14
votes
4answers
2k views

What accounted for the cost of ENIAC?

I'm used to the fact that first-generation computers were very expensive, which I had always assumed was because they contained large numbers of vacuum tubes, each of which is a rather complex, high ...
9
votes
2answers
190 views

Did any core-memory computers have a read-and-erase instruction?

Magnetic core, the primary form of computer memory from the mid-fifties to the early seventies or thereabouts, had the slightly awkward property that reading it erased it, so every time the CPU ...
2
votes
2answers
136 views

How many 6SN7 tubes did it take to store a bit?

One of the most important components of a computer is a circuit called a flip-flop, which has two stable states (that it can flip-flop between, hence the name); it is used for temporary storage of a ...
0
votes
1answer
152 views

8088 CPU A16-A19 address lines go crazy with nop test after 0FFFF address

I'm building a minimal, minimum mode 8088 computer. I started with an 80C88-2 (CMOS, static variant) CPU. My configuration is really simple. One CPU, one 74HCT245 (DTR->DT/R) for the data lines, ...
30
votes
9answers
5k views

How did early laser printers get by with so little memory?

The first HP Laserjet only had 128K of memory. To print an area of 7.5 by 10 inches at 300 DPI requires 844K if it's kept as a single bitmapped image. Obviously they were doing something clever to ...
3
votes
2answers
122 views

Could early computers use existing punch card machines?

In the early decades of the industry, computers used punch cards for data storage and transmission, partly because they were already widely used for pre-computer data processing; indeed, a major ...
4
votes
1answer
72 views

Why have both the ORG and LOC pseudo-operations in the SHARE/Symbolic/Fortran Assembly Programs for the IBM 704/709/7090/7094?

This is a fairly basic question, and I almost feel ashamed to ask it; I'm guessing it can be answered in a single sentence. There was a rather influential series of assemblers for some of IBM's ...
6
votes
2answers
503 views

Why doesn't Visual6502 simulate RRA in the way I expect?

As everyone knows, the 6502 has many many undefined opcodes. One of these is RRA, which essentially performs both ROR and ADC. From what I understand of hardware (really not much) and the explanation ...
13
votes
3answers
6k views

When did they stop verifying everything that went into a computer?

In an IBM service bureau in the early 1960’s all data was keyed twice. The first time the holes were punched into cards. The 2nd time a verifier checked that the correct holes had been punched. ...
7
votes
1answer
386 views

How does Master System backwards compatibility work on the Megadrive?

I know that the Megadrive contains the Z80 CPU to help control the soundchips for 16-bit games, and that it provides backwards compatibility for the CPU processing of Master System software, but ...
5
votes
1answer
100 views

MC68030: does execution resume during or after cache burst refill?

The MC68030 processor is equipped with dual 256-byte instruction and data caches as well as a "burst" mechanism used to quickly load a cache line from RAM or L2 cache controlled by the ...
25
votes
1answer
2k views

Why was IBM's Scientific Subroutine Package superseded?

It is a familiar fact that scientific software tends to do a lot of vector arithmetic and similar, that one does not want to keep rewriting the low-level code for such, so the usual practice is to use ...
1
vote
1answer
162 views

Startup behavior of Gameboy - what to replicate in an emulator? [closed]

I'm new here. Let me know if this is the wrong place to ask this kind of question. I'm planning to build a Gameboy emulator. Before I start, I want to have a clear understanding of the startup ...
32
votes
13answers
7k views

Why were programs entered on punch cards instead of paper tapes?

Dale Fisk's Programming With Punched Cards is a fascinating account of programming in the days of punch cards. The fundamental dynamic was that early computers did not yet support timesharing. The ...
12
votes
2answers
925 views

Why does the 6502 JSR instruction only increment the return address by 2 bytes?

Currently messing with 6502 assembly on a C64, and I don't understand why the JSR instruction is so weird. According to the instruction table, JSR is a 3-byte instruction and only operates in absolute ...
11
votes
2answers
406 views

AdLib, YM3812 and Timers

For no particular reason I started reading up on the original AdLib Music Card, and it's clear that this card was little more than a stock Yamaha YM3812 music chip (aka OPL2) glued to a PC's 8-bit ISA ...
2
votes
1answer
211 views

Microsoft C 6, far pointer, cast to int, warning C4047

Trying to access one byte in memory using segment/offset, like this union REGS in, out; struct SEGS segs; int v; char _far* p; ... int86x(...,&in,&out,&segs); p = (segs.es << 16) + ...
8
votes
1answer
827 views

How many transistors in the CDC 1604?

The CDC 1604, released in 1960, was Seymour Cray's first supercomputer, and also one of the first computers made of transistors. (The IBM 7090 was released only the previous year.) How many ...
3
votes
1answer
272 views

Building a Memory Management Unit to expand the 16Bit Address space [closed]

I'm in the middle of making an 8Bit computer, I've selected Z80, the 20Mhz version, which is cheap and readily available. Since Z80 has a 16bit address line it can only address 64KB of memory location....
7
votes
0answers
354 views

What is the origin of executable compression?

According to the wikipedia article on the topic, the earliest executable compressor listed is Realia Spacemaker for IBM PC (since 1982, written by Robert B. K. Dewar, SM.COM, signature "MEMORY$&...
0
votes
0answers
153 views

Is there any browser out there that still support Windows XP? [closed]

I want to know if there is still one browser working in 2021. Because most of the browsers like firefox or chrome need at least Windows 7, but I dont meet the requirements for Windows 7. So I stuck ...
17
votes
6answers
3k views

Are there other examples of CPU architectures mostly compatible with Intel 8080 other than Z80?

When the Zilog Z80 was released, it was marketed as being mostly ISA compatible with Intel 8080, while also providing enhanced features. Likewise, the CPU of the Nintendo Game Boy is a custom ...
5
votes
1answer
145 views

How did games written for tape-based BBC micro, get officially and unofficially ported to disk, bearing in mind extra workspace needed by DFS ROM?

If I recall, PAGE = &E00 for a BBC Model B system with cassette tape based storage. On installation of Acorn DFS ROM (with 8271 Floppy disc controller), the ROM allocated more memory, increasing ...
5
votes
1answer
358 views

3.5″ floppy drive shown as 5.25″ in Windows 98 SE

I have an old PC from the 90s. When I boot DOS from floppy, everything works fine. I have just installed Windows 98 SE and for some reason, the 3.5 inch floppy drive is showing as 5.25 inch drive. It ...
2
votes
1answer
125 views

Apple II double buffering and double high resolution

I write programs in assembly language using HGR mode. For a fluid display, I use the double buffering technique. Is it possible to use this technique in DHGR (double high resolution)? If so, I am ...
1
vote
2answers
118 views

What is the easiest way to access/convert Lotus NSF files?

Would like to read some .NSF files (preferably on Linux). Converting to PDF ideal, but anything else that uses modern formats (eg XML) is fine. When I google "nsf viewer" I get many very ...
2
votes
1answer
157 views

How to convert series of hex digits in memory into the format for use with Applesoft math subroutines

I'm trying to write a calculator program in assembly for the Apple //e. I know that there are built-in subroutines for performing all kinds of math operations involving the floating-point accumulator (...
6
votes
1answer
637 views

Why does the VICE “load” command skip the first two bytes?

I am studying assembly of the C64, and of course using VICE to do so. VICE has the load command to load data straight into the C64 RAM. I reckoned I could use that to put machine code into RAM and run ...
4
votes
3answers
227 views

What bit depth and sampling frequency could the BBC micro play back sampled sounds?

I have an archive of sample recordings with a sample playback program, the date and author in the BBC BASIC loader for the program is "(C) 1985 by DAVID J. HOSKINS" There are are about 10 ...
-5
votes
1answer
135 views

Determine exact function of (assumed) DOS executable [closed]

Somewhat related to my other question, I would like to find out the exact condition/function of a binary file with the extension .DRV and these first eighty bytes. 00000000: 4d5a 8e00 5100 1400 2000 ...
0
votes
0answers
78 views

What is a good general-knowledge-level title description of Dr. Aho's and Dr. Ullman's body of work for which they were awarded the 2020 Turing Award? [migrated]

I recently read in the New York Times that my old "Data Structures and Algorithms" class professor Dr. Ullman had received the Turing Award along with Dr. Aho. The article title was "...
1
vote
1answer
66 views

How to write Apple IIgs .po disk images to Floppy Disks with an older Mac

I recently acquired an Apple IIgs with two 3.5" floppy drives and no hard disk. I'm very seasoned with older Macs, but I have no experience within the Apple II world. I search for a way to create ...
8
votes
1answer
425 views

Could the BBC micro's analogue input be used to sample sound?

Reference: BBC Micro analogue in A custom connector would be required between this D-shape rows of pins port and a standard input socket for phono/rca or 3.5inch or 1/4inch jack. What would be the bit ...
5
votes
0answers
201 views

Were vertical monitor arcade games programmed differently from those with horizontal monitors?

Many classic arcade games like Pac Man (Namco 1980), Assault (Namco 1988), Mercs (Capcom 1990), etc, use a monitor oriented vertically. I assume that they used the same physical hardware, with the ...
6
votes
5answers
787 views

Ideal resolution for color computer on PAL/SECAM

Suppose you were, in the early eighties, designing a color computer to run on an PAL TV with a free hand to choose the specifications within the limits of the technology of the time. What would be the ...
13
votes
5answers
4k views

Why didn't early color TV sets accept RGB input?

Early PCs generated RF signal, and later Composite video or S-video, to use a TV set as monitor. Why didn't color TVs of those days expose a analog RGB interface for direct connection from VCR/PC or ...
8
votes
1answer
760 views

What was the 1 MHz bus used for on the BBC micro series?

What was the 1 MHz bus used for on the BBC micro series and how did it compare with the TUBE in terms of speed/bandwidth? I read somewhere that EPROM programmers used the 1 MHz bus, but anything else?
6
votes
2answers
255 views

DEMOS commands: Cyrillic or Roman letters? Uppercase or lowercase?

DEMOS was a Soviet operating system derived from BSD Unix. Commands in BSD are derived from English words. Did DEMOS use these same commands, develop their own commands but retain the Roman alphabet,...
3
votes
2answers
169 views

C64 KERNAL Loading into I/O space [duplicate]

On a Commodore 64, if I Load "*",8,1 and the file's address (first two bytes on disk) is $D000, will it load to the RAM under the I/O space? In other words, does the KERNAL loader properly ...
4
votes
3answers
848 views

Early vector computer displays: off-the-shelf oscilliscope, or custom built?

Some early computers had vector displays, which allowed the computer to draw graphics by steering a cathode-ray beam. Some examples include the Whirlwind, TX-0, TX-2, and PDP-1. It would be easy for ...
4
votes
0answers
94 views

CDTV board rev 2.3 can OCS Denise be upgraded to ECS

I came across this post from a user 18 years years ago, where he had some luck in upgrading chips on the board 2.3. is it possible? He says he was able to get 2MB chip ram and ECS Super Denise, can I ...
28
votes
6answers
7k views

Was there a specific benefit to inverted (XOR) mouse cursors other than aesthetics?

As far as I can remember the inverted (aka "XOR") style of mouse cursor has been around as long as there have been mice. I mean something like this: (source) where the cursor shape is ...
0
votes
1answer
405 views

Help me identify game from 90s

I can remember below pointers off the top of my head: It was an adventurous game We had to cross different levels (can relate to Mario for instance) The protagonist was short and was wearing a cop ...

15 30 50 per page
1
2 3 4 5
83