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10
votes
3answers
277 views

VIC-20 vs. VC20 (or VC-20)

My first computer was a VC20. Was it just renamed (for the German market?) as a VolksComputer? (I am a Finn and the VC was bought in Finland). Or were there any actual differences to VIC-20?
10
votes
8answers
739 views

Was it possible to write a novel on a BBC Micro 16kb/32kb memory era computer without expansions?

BBC Micro model B has 32k memory. An average book, like Mary Shelley's Frankenstein, has about 350,000 characters in it. So you'd need over 10 times the memory to load it in, plus the software to edit ...
3
votes
3answers
113 views

What’s the most advanced os I can run on a non memory management pdp11 (ie 11/20)

Building my own emulator. I only have the basic , no memory management, model going (11/20?). I started with caps11. What’s my best choice for a disk based os. EDIT: and of course if anybody has the ...
2
votes
2answers
40 views

Can I rewire a compact Macintosh SE or other compact Mac to play RCA Video?

I would like to take a compact Mac such like Macintosh SE, completely neglect the computing part of it, but be able to feed the CRT tube with an external video feed through Analog RCA cables. (Yellow ...
1
vote
1answer
33 views

Part number / model for IBM PC 350 keyboard

what was the part number or model of the original keyboard shipped with IBM PC 350? Trying to restore the full set.
11
votes
5answers
2k views

What was novel about the Atari ST? Did it introduce any innovations?

Recalling the rise of 16bit era, an era that in my memories was defined mainly by Motorola 68k cpu computers: The Mac, brought the GUI interface. The A bomb, the Amiga, with its custom chips-...
7
votes
5answers
1k views

Pulling my hair out over a 4-bit architecture, there ought to be some law here somewhere, is there? [closed]

I am trying to build the most simple CPU possible. And doing it on bread boards. There is a popular movement, one of the biggest protagonists of that being a certain Ben Eater, who is a good teacher, ...
16
votes
12answers
6k views

How can a Z80 assembly program find out its own memory address?

I'm wondering how to write a program in Z80 assembler that discovers its own memory location. I thought that maybe I could somehow load the program counter PC into, for example, BC. Is there a way ...
11
votes
3answers
2k views

Where can I find software that was designed for Windows 1.0?

Once every decade I get the itch to boot up a Windows 1.0 environment to poke around at it and marvel at how far we've come. However, in any of the environments I've seen (say PCjs), they never seem ...
22
votes
7answers
4k views

Why were “data modems” so much more expensive compared to “fax modems” back in the day?

In 1997, my uncle visited and gave me a "fax modem" which he installed on our 486 PC and then managed to transfer over a fax document from a real fax in his home to our computer, running ...
20
votes
11answers
6k views

640x480 color display in 1980

I'm working on an alternate history story in which the protagonists, Silicon Valley computer entrepreneurs, are trying to release a graphical workstation in 1980, with the capability of displaying ...
23
votes
6answers
23k views

How can you connect an Amiga 500/600/1000/2000 to a modern monitor?

I have an Amiga 500 that I'd like to get up and running again, but the 1084 monitor with which I used to use it has flyback transformer issues. What options are available to hook it up to a modern ...
9
votes
9answers
2k views

How did dusty deck Fortran handle overflow?

In Fortran 77, numerical code that ran on IBM, CDC, Cray etc, how was overflow typically handled? Did it raise an exception? (I would expect such an exception to be inexact on vector machines, i.e. to ...
90
votes
8answers
27k views

Why would a NES game use an undocumented 1-byte or 2-byte NOP in production?

Reading the NESdev wiki page on CPU unofficial opcodes, I see a few games use an undocumented 2-byte NOP instuction in production: Puzznic, F-117A Stealth Fighter, and Infiltrator use $89 #i. Beauty ...
0
votes
2answers
195 views

Understanding Mario and screen position in “NES-Super Mario Bros”

Objective - Play Mario game and record the score and position, and later map it to level map png (https://nesmaps.com/maps/SuperMarioBrothers/SuperMarioBrosWorld1-1Map.html) Method - I can get the ...
1
vote
0answers
57 views

Frozen horizontal width coil in old CRT monitor

I have an old Apple IIe CRT monitor which could use a small horizontal width adjustment. Unfortunately, as I try to rotate the hex key in the coil with a CRT adjustment tool, it doesn't want to move. ...
19
votes
2answers
1k views

How was the 80186 incompatible with the IBM PC?

According to https://en.wikipedia.org/wiki/Intel_80186 The 80186 would have been a natural successor to the 8086 in personal computers. However, because its integrated hardware was incompatible with ...
5
votes
1answer
319 views

Which were the best selling early MS-DOS PCs apart from the IBM PC?? [closed]

The IBM PC in 1981 was rapidly followed by a rich ecosystem of computers with x86 CPUs running MS-DOS, not all of which were compatible at the hardware level. There is a list of some early MS-DOS ...
4
votes
7answers
1k views

Any ways to have an architecture with a different base than base16? [closed]

I was reading this Wikipedia entry and thought if any other Computer/or Architecture was ever made with a different base system than base16. And if not, any ways to do it? (maybe by making one from ...
1
vote
1answer
56 views

How many different standard boot sectors are there for Apple II DOS 3.3?

When formatting a blank 5¼ disk on an 8-bit Apple II using the INIT command, was there only ever one variation of the boot sector code that was written, or was it updated from time to time over the ...
19
votes
4answers
5k views

Were there any 8-bit CPUs with 24-bit addressing?

Or was that something that didn't appear until later CPUs (around the time of the 286 maybe)? Also, how would I go about researching this on my own? It's not exactly something I can look up on ...
10
votes
3answers
719 views

Where can I donate my old Computer Shopper Magazines to make sure they get scanned and shared?

I am sure many of you remember the gigantic Computer Shopper magazines of the 1990's; but Computer Shopper actually dates back to sometime in 1979, and still exists in electronic form today. In my ...
19
votes
1answer
1k views

Apple IIgs: Hardware implementation of RAM shadowing

On the Apple IIgs, the 256K of built-in main memory is divided into two sections: The "fast" RAM, banks 00 and 01, and the "slow" RAM, banks E0 and E1. CPU access to slow RAM required the CPU to slow ...
14
votes
4answers
2k views

Why did some Spectrum games need LOAD “” CODE?

Most ZX Spectrum games were loaded from tape, and the traditional way of starting the loading process (at least in the 48K era) was to type LOAD "" and then start the tape. This would normally load ...
4
votes
1answer
52 views

Determining which sectors in an Apple II floppy disk/image are used when the boot sector declares more than 1 sectors

The Apple II disk bootstrap process looks at the first byte of track zero sector zero to see how many sectors long the bootstrap code will be. It then loads these sectors at location 0x0800 and jumps ...
1
vote
4answers
156 views

Which part of a computer does the conversion between binary to hexadecimal? [closed]

I know most computer architecture store data in binary in drives/storage, but i'm unsure where in a computer (x86, etc) does the conversion/interpretation of binary (base2) to hexadecimal (base16) ...
12
votes
5answers
2k views

What was the first mass-market, 16-bit microcomputer system?

To qualify what I mean by "16-bit microcomputer system", I am talking about a system that has not only a 16-bit (or 32-bit) microprocessor CPU, but also a 16-bit wide external data bus connected to ...
7
votes
2answers
602 views

Build a hardware clone or emulator of Apple II?

These days we are constantly seeing low-cost boards that have huge power (raspberry pi, various arduino-like microcontrollers.) I am hoping I could make, or get, a clone or emulation of an Apple II ...
15
votes
6answers
3k views

What was the first Unix version to run on a microcomputer?

I have read that the first version of Unix was created for the PDP-7, and later versions were created for the PDP-11. But I am wondering, what was the first Unix version to run on a microcomputer?
0
votes
1answer
58 views

WWDC2010 Game Demo, programmers use what format for 3D model and animation? [closed]

People in Apple Corporation make Quest game demo for WWDC in year 2010: • Game Design and Development for iPhone OS, Part 1 · Session 401 • Game Design and Development for iPhone OS, Part 2 · Session ...
5
votes
1answer
91 views

How to get GOTEK to work with CDTV?

I'm trying to connect Gotek drive to my CDTV using external caddy (amitek). The drive has 3 digit LED display, after boot i can see F-F. When I insert Flash drive it detects images on it, I can ...
4
votes
2answers
202 views

What speed should CDTV CDs be burned at

CDTV uses proprietary CD drive at 1x speed. Most burners out there cannot run slower than 4x, x8. Same for CDs as the lowest I found was 2x. What speed should I burn it at to be able to use it with ...
52
votes
3answers
9k views

On DOS computers, what would the PARK command do?

In 1994 or so, we had an old computer at my primary school. I remember finding out that it had a park command. From reading its documentation, it said that this command should be executed prior to ...
12
votes
2answers
2k views

What is the instruction set of the PDP-7?

The PDP-7 was a bookshelf-sized "minicomputer", with keyboard, magnetic and paper tape and printer I/O. According to Wikipedia, the first version of UNIX (then named Unics) was programmed in assembly ...
20
votes
2answers
2k views

Did playing sounds on the PC speaker keep the CPU busy?

The IBM PC and early successors came with an internal speaker that could play simple sounds. According to https://en.wikipedia.org/wiki/PC_speaker However, because the method used to reproduce PCM ...
41
votes
12answers
6k views

What languages are better fit for generating efficient code for 8-bit CPU's than C?

I found Why do C to Z80 compilers produce poor code? very interesting as it pointed out that C (which was designed to be an abstraction of a CPU for porting Unix) was not a very easy language to ...
2
votes
2answers
126 views

How can the composite out of an Apple II be disabled?

The PC Transporter provides composite out via a cable run to the internal video header of the Apple II. In order to do this, I assume it has to disable the sync and colorburst generators so the Apple ...
8
votes
1answer
103 views

Is scratchpad register 15 directly addressable on the F3850 (except as QL)?

The Fairchild F8 CPU, the F3850, has 64 scratchpad registers. The first 12 of these are directly addressable by several instructions. For example, the opcodes $CX add the contents of scratchpad ...
6
votes
1answer
170 views

Which x87 first acquired the ability to flush denormal to zero?

On modern Intel FPUs, you can set a flag to cause all denormals to be automatically flushed to zero. On some workloads, this improves performance. I cannot find any mention of that flag in the data ...
11
votes
0answers
202 views

How much did Atari pay for GEM?

Atari licensed Digital Research's GEM graphic user interface for the ST. As https://www.filfre.net/2015/04/the-68000-wars-part-2-jack-is-back/ puts it: And of course in the wake of the Macintosh the ...
6
votes
1answer
157 views

How to quit MBASIC and return to CP/M?

I've tried everything I can think of. EXIT QUIT END STOP BYE Q…
9
votes
1answer
820 views

What was the performance penalty for denormal inputs on 80s-era FPUs?

Some FPUs exhibit as much as an order of magnitude slowdown when given denormal inputs, due to having to trap to microcode to handle them. Did early FPUs of the microprocessor era, exhibit substantial ...
11
votes
3answers
2k views

Swapping endian-ness on the 68000

In the 80s, the two great 16/32-bit desktop CPU architectures were the x86, used in the IBM PC and compatibles, and the 68000, used in the Amiga, Atari ST, Macintosh, early UNIX workstations and ...
2
votes
1answer
55 views

What is _KBSE (Keyboard Sense) signal in CDTV and what is it used for

I just managed to unmod CDTV keyboard (swapped wires for CD32) with community's help, but the original wire was gone, so I'm left without _KBSE signal connected. It seems the system doesn't mind. What ...
3
votes
1answer
116 views

How to unmod CDTV keyboard

I have a CDTV keyboard that someone modded to work with CD32. There are no bridges or extra components on the board, however pinout was changed at the board - wire connector and I'm not sure how to ...
2
votes
1answer
95 views

Are there open source Java libraries for reading DSK and EDSK disk image files as used by Amstrad and Spectrum +3 emulators?

I've been working on some modules for the Ghidra reverse engineering tool. Ghidra is written in Java, which I'd always avoided when I was more actively programming so this is an opportunity to learn ...
4
votes
1answer
191 views

Does anybody have the PDP-11 CAPS-11 source code?

CAPS-11 is the Casette Programming System for the PDP-11. The manual is available at Bitsavers, binaries can be found at SimH. The manual contains instructions how to assemble the system from source, ...
8
votes
2answers
409 views

Is integer arithmetic really slower than float with (early) MS-BASIC?

This question is based on a comment by Neil on another question regarding integer-multiplication: Do you have any citations for your claim that most MS-BASIC integer multiplication was done by ...
4
votes
1answer
81 views

Are there any CHIP-8 games that break if `SAVE` / `RESTORE` *doesn't* change the pointer register?

The CHIP-8 instructions SAVE Vx (Fx55) and RESTORE Vx (Fx65) are originally specified to increment the pointer register I as each register is saved/loaded, so by the end of the instruction, the value ...
-2
votes
0answers
48 views

Does anybody have the source code of the PDP11 Cassette OS CAPS11 [duplicate]

[re-asking cos the first time I asked it got closed saying there was not enough detail, well I think there is enough detail now] CAPS-11 is the Casette Programming System for the PDP-11. The manual is ...

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