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9 views

MIPS Encoding of blez/bgtz vs bltz/bgez

In the MIPS architecture, blez/bgtz and bltz/bgez are encoded differently: blez/bgtz are encoded as: [BLEZ/BGTZ: 6 bits] [RS: 5 bits] [0: 5 bits] [OFFSET: 16 bits] bltz/bgez are encoded as: [REGIMM: 6 ...
2
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0answers
51 views

What was the specific function of the relay which captured Grace Hopper's famous “bug”?

Computer pioneer Grace Hopper often recounted the story of her team finding the first physical computer bug: While she was working on a Mark II Computer at Harvard University in 1947, her associates ...
4
votes
1answer
52 views

How much did the RM 380Z weigh?

The Research Machines 380Z was an early British microcomputer, released in 1977. Unlike many other early microcomputers, the design was industrial style, a hefty metal box, sometimes described as '...
0
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0answers
22 views

Z80: Interrupt (IM2) daisy chain for “foreign” peripherals

I'm looking for a way (apart from manually wiring up Fig.15 of The Z80 Family Program Interrupt Structure) to daisy chain "non-Z80-family" devices in an IM2 Z80 system i'm designing. So far ...
3
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1answer
104 views

Whatever happened to the Refal language?

Refal is a language from the 1960s that is based on the concept of pattern-matching with many features that could be considered advanced even today- it is functional, garbage collected, and supported ...
5
votes
1answer
110 views

VAX 11/780 16MB memory board - what was the physical size?

I'm trying to get a feel for what it looked like when you designed a computer to have a lot of memory chips stuffed into it. To that end, I found this: https://commons.wikimedia.org/wiki/File:...
18
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7answers
4k views

Did computer games for Commodore 64 really take “25 minutes” to load “if everything went alright”?

In the Swedish-language song "Nostalgi" by Markoolio from 2003, some of the lyrics go: My first computer had 64 kB you surfed on the water, and that's that The computer games were loaded ...
2
votes
0answers
111 views

How did the NSA use vector supercomputers?

In the 80s, the NSA was a major customer of supercomputers. https://www.nsa.gov/Portals/70/documents/news-features/declassified-documents/cryptologic-quarterly/NSA_and_the_Supercomputer.pdf discusses ...
7
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5answers
1k views

Why was there no 32bit or 64bit versions of M68000 & 65xx line of CPUs?

I don't understand why western design centre made the 65816 a 16bit upgrade to the 6502 but commodore semiconductor group/MOS technology didn't make their own variant & why neither company made ...
1
vote
2answers
125 views

How plausible is this data corruption on an IBM 9-track tape?

Preamble For a while, I had a copy of a BESM-6 Pascal compiler which worked only on very simple programs, like "Hello, world", and would throw a division by 0 exception on anything more ...
19
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3answers
5k views

How did games like Doom offer free trials? What was packaged in their free trial software packages?

I remember that Doom had a free trial version where you can play the first episode but the other two you have to buy. There are other games that did that as well. If I understand it, in order to do ...
0
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1answer
192 views

Flag “hidden” on partitions and Microsoft

In this website (and in others, of course) you could be informed that there is a special form of partition flag ("hidden") to avoid detection by Microsoft operational systems. First: Is ...
0
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1answer
47 views

How to flash CDTV extended ROM using development board

I have a CDTV ROM development board, and I know it is possible to flash it using floppies. How to make such floppy with a custom rom?
3
votes
1answer
216 views

Trying to recall an OS I worked on that was called CPM but was not DR's CP/M

I'm trying to trace a type of system I did a little work on in my first job, which was for a company which no longer exists and I am not in regular touch with most of my former colleagues. It was a ...
6
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2answers
1k views

What specific factor(s) made Thomas Watson, Jr. (of IBM) so enthusiastic about early electronics?

One of my favourite computer history books is Stan Augarten's "Bit by Bit", which has an author-approved scanned copy at http://ds-wordpress.haverford.edu/bitbybit/ In it, the author makes ...
3
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1answer
146 views

Commodore 64 CC65 - I need help with config set up for using a data segment in Bank 3

I'm developing a game for C64 using CC65 to compile my C code to ASM. To get started quickly, I have been defining the data for my sprites in C arrays and then copying the data in those arrays to the ...
2
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0answers
75 views

advice for retrieving functions and tables from intel 8061/8065 bin file (reverse engineering) from Ford EECV ECU

I have under my disposal some Ford EECV bin files and my goal for the next few weeks is to retrieve the functions and tables and plot them out before going onto DIY hardware . . Does anyone know which ...
3
votes
1answer
184 views

What old version of Windows provides out-of-the-box DVD movie playback?

I bought a Playstation 2 in 2000, which famously included a DVD drive capable of playing DVD movies. I wanted the same movie playback capability on my Windows 98 PC. As I recall, I mistakenly thought ...
-5
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1answer
172 views

Why do old, network-connected consumer computers from 1980-1999 scare me? [closed]

For this question to be answered correctly, it's necessary for me to establish some context. I was born 1985. I'm neither a very young person who grew up with "smartphones", nor so old that ...
4
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2answers
302 views

CPC BASIC “CALL” command

Recently I've been playing around with an Amstrad CPC emulator. I haven't written BASIC code for years, but back in the day I did actually use a CPC for real. Anyway, looking at documentation online, ...
8
votes
1answer
1k views

Is the NeoGeo capable of raster effects?

The Neo Geo has incredibly powerful sprite based hardware, but can it do raster effects? Raster effects are where changes to the graphics hardware registers are made mid frame, usually timed to be in ...
15
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1answer
418 views

Where and when did the “.s” suffix for assembly-language source files originate?

The closest I was able to find on StackOverflow is What are .S files?, in which no answerer addresses why we use .s for assembly. (And .S for preprocessor/macro assembly; and gcc -S to produce ...
2
votes
1answer
168 views

How to get started with writing drivers for amiga OS

I would like to learn how to write drivers for Amiga OS. Seems like a daunting task, but I have spare time and I find great value for amiga (CDTV) community in particular. Currently if a CD ROM breaks ...
0
votes
4answers
137 views

How did graphics processing for old 8/16bit consoles work & what are the differences between an FPU/maths co processor & a graphics card? [closed]

When looking on the internet at information about old consoles it's pretty easy to find out information on CPUs like the 6502, 65816, 68000 & Z80 used in retro computers & consoles like the ...
5
votes
3answers
1k views

1980's commodore 64 game about flying toward tower

Wondering if anyone can help me shed some light on this vague memory I have as a kid. My older brother had a friend who got us tons of pirated games for our commodore 64/128. I'm trying to recall one ...
-4
votes
1answer
178 views

Is the Raspberry Pi Model B (2014) technically inferior to an original Xbox (2001) in compute power/specifically for emulators? [closed]

(I first asked this in the Raspberry Pi section, but it received no responses. I think this, Retrocomputing, might be a better fit.) I the year 2003, I had my Xbox chipped in order to be able to run ...
3
votes
1answer
173 views

Does a defacto format exist for Commodore 64 SID music?

I first learned about tracker / mod music on my Amiga in the early 1990's. I remember fooling around with Protracker, listening to mods with Intuitracker, and coming to the realization that all those ...
11
votes
3answers
1k views

Is this the reason why fread/fwrite has 2 `size_t` arguments?

It just came to me that, the C standard I/O functions fread and fwrite are having 2 size_t arguments because of I guess possibly, that on some systems, there may be more memory of which whose size can ...
6
votes
2answers
184 views

Are there any known 8086 systems that would dynamically switch between XTAL and EFI clocks on 8284 clock generator?

In an typical 1980s 8086 system the 8284 clock chip is typically used to generate the clock for the CPU. The 8284 has two clock sources XTAL and EFI. XTAL provides a steady clock source from a ...
19
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3answers
2k views

Could a single NES ROM cartridge run on both PAL and NTSC systems?

Most ROMs are labeled with "(Europe)" or "(USA)", meaning PAL or NTSC. However, some are labeled "(World)". At first, I didn't think twice about this, just assuming that ...
2
votes
2answers
227 views

GW-BASIC : Methods of making Self-modifying programs?

GW-BASIC : Methods of making Self-modifying programs just using Basic ? I wonder if GW-BASIC may have had a method for allowing the creation of Self-modifying programs just using Basic, without ...
20
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5answers
5k views

When IPv6 was designed were there any specific considerations for other planets?

Seeing Moon base internet functionality in Worldbuilding reminded me of how I began an old Space SE question Are there discussions or plans for extending the internet into space beyond Earth? Many ...
5
votes
1answer
197 views

What is the easiest way to get an Amiga online?

I'm working on my ultimate CDTV setup, few hiccups along the way with CDROM access on TF536, but we will cross this bridge. As of right now I'm only missing and internet access, before I can finally ...
50
votes
1answer
6k views

How was collision detection done on the Asteroids arcade game?

In honor of today's landing of and sample collection by the OSIRIS-REx spacecraft on the asteroid Bennu: How did the arcade game Asteroids detect collisions between the screen objects (player's ship, ...
10
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0answers
176 views

Rationale for almost heatsunk TO-220 packages on C64 motherboard

The TO-220 packaged VR1 regulator and Q1 transistor in the Commodore 64 motherboard (reference designators cited here from the Rev. B breadbin) are mounted in a way that suggests they were supposed to ...
2
votes
2answers
300 views

How is it possible that this “Polymega™” console will “not support” Everdrives?

I'm reading here: https://polymega.com/faq/ WILL EVERDRIVES, GAME GENIES AND MULTI-GAME CARTS WORK WITH POLYMEGA™? Polymega™ does not support Game Genies or Everdrives. How is that possible? What's ...
2
votes
2answers
124 views

How to limit RAM available to Workbench

Is there a way to limit Fast RAM used by Amiga OS 3.1, i.e. if A500 with 030 MMU detects full 64MB in address ranges 0x40000000 to 0x44000000. Instead, can I choose to map only 8MB in lower ranges at ...
2
votes
2answers
976 views

Why does changing a DOS/Windows EXE cause it to not run? [closed]

If I hex-edit an EXE for DOS or Windows, by adding or removing some text for example, it will no longer run. If I just change a single char around to a different one, it may run. Is this some anti-...
0
votes
2answers
229 views

Behaviour of commas in PRINT at a line-end

Does anyone have actual documentation on how MS/Commodore BASIC handles line wrapping in PRINT statements? I tried this in an online emulator: PRINT 1,2,3,4,5,6,7,8,9,0 In this case it wraps at the ...
2
votes
0answers
167 views

Cold war submarine game for the ST

I'm trying to recall the name of a game I spent too much time playing on my ST. It was a simulation of cold war sub combat. It took place entirely on a map view, where you controlled NATO subs, ...
6
votes
3answers
1k views

Did any 8-bit versions of MS BASIC allow user-defined string functions?

My BASIC is almost working, the almost being the DEF FN. Just so I don't paint myself into a corner, is there any "mainstream" BASIC from the 8-bit era that allowed user-defined string ...
3
votes
1answer
233 views

How to run CP/M 2.2 on IBM PCjr (Not CP/M-86)

Years ago, I upgraded my IBM PCjr with a V20 and I was able to run CP/M 2.2. I have been looking for a CP/M 2.2 image that I can run on my current PCjr with 640K and Dual floppy (RACOR expansion). ...
2
votes
1answer
210 views

How likely is it that a ROM could be “corrupted” resulting in visual artifacts during gameplay? [closed]

I watch a lot of retro game streams. Frequently, whether they are running on a software emulator, hardware emulator (Retron 5 or whatever), or an Everdrive, whenever there is some weird glitch in the ...
5
votes
1answer
157 views

Why is my program outputting only zeros to data bus during IO operations?

I'm building a breadboard Z80 based computer. As now, I have the CPU hooked up to an eeprom and an IO device (an HD44780 character display) with appropriate decoding logic. The rom chip starts at ...
23
votes
6answers
6k views

Why are old CPUs like MOS Technology 6502 and Motorola 68000 considered better for real time systems applications than modern x86 based CPUs?

Reading the Wikipedia article about real-time computing, I found written that: Once when the MOS Technology 6502 (used in the Commodore 64 and Apple II), and later when the Motorola 68000 (used in ...
4
votes
2answers
178 views

Detecting the number of disk drives installed

When the BIOS gives control to the MBR (or the bootloader, for non-partitioned media), it passes the drive number from which the bootloader was loaded in the DL register. This number is most of the ...
4
votes
1answer
111 views

Is it possible to change keyboard key maps on System 6?

For aesthetic reasons, I would prefer to run a US-english variant of System 6.0.8, but all my keyboards are of a Scandinavian layout. Is it possible to swap key maps (using ResEdit?) to use my Finnish ...
10
votes
2answers
659 views

What pointing devices were available for C64/C128?

Apart from 1351 mouse what other official Commodore C64/C128 pointing devices were available, or notable 3rd party like Mouse Cheese. Joysticks and controllers are out of question. C64-wiki seems to ...
7
votes
1answer
1k views

Questions about Security over Using an Ancient Mac Computer on The Internet

I've managed to get my hands on a really old mac computer that was probably built in the late 90's. The operating system was last updated in 2001 to 10.1.4. The problem is that I'm not sure if it's ...
9
votes
1answer
207 views

Trying to create a filesystem ROM for Amstrad CPC but tape is still waiting

Some background: I want to create a CPC MicroSD interface, so my first step is trying to hook the CAS* jumpblock entries just like AMSDOS and other DOSes do. My first goal is to override CAS CATALOG ...

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