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16
votes
5answers
3k views

Can the wrong sync frequency really destroy a CRT monitor?

I've read in various places that an incorrect signal of the wrong refresh rate can cause physical damage to a CRT monitor, but I've never found an adequate explanation of why this is so. Is this true? ...
8
votes
3answers
654 views

How to do I/O with emulation code?

I have a partly-written emulation program for the 8086 CPU. And I'm not sure how to go about adding I/O capabilities to it. The emulator implements a subset of the 8086 instruction set described here. ...
9
votes
1answer
639 views

Is there any reason to chose ES, FS, or GS over the others in real mode?

The Wikipedia page on X86 Memory Segmentation says In real mode, the registers CS, DS, SS, and ES point to the currently used program code segment (CS), the current data segment (DS), the current ...
17
votes
9answers
3k views

What caused the demise of BASIC/BASICA in the late 1980's?

While not strictly adhered to, this is somewhat of a generalization of computer listings found in the more popular magazines of the time - BYTE, Kilobaud, PC Computing, etc. This explains the ...
4
votes
1answer
368 views

Identifying an old one-bit image file format

I've found some code for reading an old image format, and I'm trying to figure out what format it is. Attributes of the file format I've deduced from reading the code: The image file begins with a ...
10
votes
2answers
603 views

How did the Microprofessor II have space for a Chinese font in the ROM?

There's an Apple II clone from Taiwan which apparently forgoes the text mode and just has a graphics mode because it's simpler that way to render Chinese writing. It had a 16K ROM, of which 12K is a ...
8
votes
4answers
7k views

Connecting Iomega Zip (parallel port) to modern PC

Am wondering what would be the easiest way to connect an Iomega Zip drive (parallel port version) to a modern PC. I note there are USB to IEEE 1284 adapter cables, but would be very surprised if this ...
8
votes
8answers
2k views

Source code control on an MS-DOS system

This isn't quite so much a question about how it was done "back in the day", but what my options are today for source code/version control on an MS-DOS machine. I enjoy tinkering with Turbo Pascal, ...
2
votes
2answers
429 views

Is emulation ultimately the future of retro computing? [closed]

As you probably know, nothing really lasts forever in the human-made world of appliances, especially electronic ones. Whether it stems from market evolution, technical advancements, newer paradigms, ...
14
votes
7answers
1k views

New 6502 BASICs?

I sort of "have a thing for BASIC" right now, which has led to a couple of great exchanges here in RSE about the variations "back in the day". I'm wondering if anyone is aware of other modern BASICs ...
7
votes
1answer
594 views

Testing RAM on a 386

I've got an old 386 laptop - specifically an OmniBook 300 - and I'm a little suspicious of the RAM. It's exhibited some very odd symptoms, such as memory-related crashes and boot failures, so I'd like ...
9
votes
4answers
1k views

Is a normal B&W TV good enough for 80-column text?

S-100 bus machines normally had displays that had 64-chars-per-line. The VDM-1 used a 7x9 format, and I think most cards used that, so that would be 448 pixels. I understand that an NTSC television ...
21
votes
4answers
3k views

Why does the Z80 include the RLD and RRD instructions?

The Z80 has an instruction RLD, which apparently treats the lower 4 bits in the accumulator and the full 8 bits in (HL) as a twelve bit integer which it then rotates left by 4 bits. The carry flag ...
13
votes
1answer
727 views

Fortran variable type defaults - origin

In older versions of Fortran, e.g. 77, variables did not need to be declared. If the name starts with I, J, K, L, M, or N then it would be assumed to be an INTEGER. Otherwise, it would be assumed to ...
3
votes
1answer
1k views

Is it possible to make VICE load .prg files faster?

When I load a C64 .prg with the Hoxs64 emulator, my .prg loads pretty much instantly. But when I load the same .prg file with VICE (x64 app.prg) it takes quite a while (depends on memory map, but ...
2
votes
2answers
223 views

Mysterious things happening to stack when running a debug session

When I run a debug session using Freedos and debug.exe, I get a session like the following. I've added a description of what I saw as annotation on the image. Each step, I've printed out the stack ...
42
votes
22answers
14k views

How were files transferred between different systems in the late 1980s?

Today there are adapters available allowing you to connect historic floppy drives to a modern PC. This allows you to copy data from historic floppy disks to the PC. In the late 1980s and the early ...
10
votes
1answer
597 views

Can we express the instructions to the Analytical Engine in terms of assembler or machine code?

On a recent trip to the London Science Museum I saw Babbage’s Analytical Engine. Apparently this had an ALU (or equivalent). I can build an ALU out of logic gates but I can’t conceptualise how to do ...
3
votes
2answers
608 views

What's the fastest Apple II (sans accelerator card)?

The candidates are: Apple IIgs, with its 2.8 MHz 65816 CPU, running in 65C02 "emulation mode" Apple //c+, with 4.0 MHz 65C02, but overclocked to 8.0 MHz Laser 128EX with 3.6 MHz 65C02 I want to know ...
8
votes
1answer
929 views

What was the name of the object-oriented C language I used in the 1980s on the Mac

I clearly recall working with an object-oriented C derivative on the Mac but I cannot find any definitive references to it. It was back in the days of System 7 and later System 8. It had both ...
3
votes
2answers
867 views

3D Printed Replacement Key Caps for Atari 1040ST

How can I replace/repair broken Atari 1040ST key caps using 3D Printer? Switches are in good condition. Only the key caps are to be replaced. Did Atari followed any industry standards like Cherry MX,...
17
votes
2answers
671 views

How to create a switchless multi-system 2 button Atari joystick?

All systems that use the Atari 9 pin joystick standard make use of the following pins in consistent ways, with each direction and the fire button being connected to the ground pin when pushed. 1 - up ...
6
votes
4answers
671 views

What was the 2nd best selling computer ever? [closed]

It's widely known that the Commodore 64 was the best-selling single model of personal computer. Which computer make & model got second place? To clarify, I'm looking for an objective answer about ...
7
votes
1answer
428 views

Differences between 4k, 8k and Extended Altair BASIC?

Various histories state that there were at least three versions of Altair BASIC, 4k, 8k and Extended - plus modifications like Disk. I've found some listings of the 4k, but does anyone have a short ...
16
votes
3answers
633 views

How widespread was the 'test' activation code for Microsoft products?

Inspired by this question, I recall that many of the older Microsoft products from Windows 3.1 through the late 90's / early '00s supported a 'test' activation code of all 1's. I did this a few times ...
6
votes
2answers
268 views

How can you reset the behavior of ONERR in AppleSoft BASIC?

In an Applesoft BASIC program you can use the standard MS-BASIC ONERR statement to perform error trapping. For example: 10 ONERR GOTO 100 20 POKE 0, 400 : REM INVALID VALUE WILL CAUSE ERROR 30 END ...
2
votes
1answer
241 views

Is it possible to use the BRK instruction when ROM is banked out?

I used to use the BRK instruction when debugging on the C64. However, when I bank out ROM with... lda #$35 // Bank out kernal and basic sta $01 // $e000-$ffff ...the BRK instruction (...
14
votes
2answers
2k views

How did Windows 95 verify the Certificate of Authenticity?

After setting up Windows 95 in a virtual machine, I noticed that it could verify the product key without internet (no serial ports or network adapters). From modifying a genuine key at the CoA (...
21
votes
2answers
4k 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 ...
16
votes
5answers
2k views

What specific technical advance(s) allowed PCs to play “Full-screen full-motion” video?

In the early 1990s, the new buzzword for PCs was "Multimedia", and the gold standard for multimedia performance usually talked about was "full-screen full-motion" video playback. Many will remember ...
23
votes
3answers
2k views

BBC/Acorn BASIC, what made it so fast?

As I look over old versions of BASIC trying to piece together their history, I come across repeated indications that BBC Basic was really fast. One list puts it running the Ahl benchmark (for all its ...
12
votes
3answers
2k views

What's a good way to implement this “fade” effect on C64

See the beginning of https://www.youtube.com/watch?v=hmfLBAtGAKk. Here's a screenshot: It basically clears characters pixel by pixel both horizontally and vertically. Use sprites for the pixel by ...
20
votes
5answers
5k views

Was it feasible to create Win16 software using pre-existing DOS development tools?

It seems that right from the outset, the plan for Windows development was that it would be done with a separate set of compilers specifically equipped for that purpose. The Windows SDK comes with ...
6
votes
4answers
354 views

BASIC-PLUS inline operators, do they actually make sense?

Of the features that were not copied from BASIC-PLUS to MS BASIC only one seems to be a good idea, and I'm not sure it really is. I'd like to hear from people that have opened the guts of MS BASIC to ...
5
votes
1answer
181 views

How to diagnose a failed capacitor on the mainboard?

My Fox II 286 mainboard just blew a capacitor. I haven't yet powered it on, so maybe the cap was bad. How can I diagnose this problem, and eliminate other bad caps?
4
votes
2answers
161 views

Archiving data on a nonmagnetic storage [closed]

I know that we have LTO tapes, which have really good longevity and are reliable. But they're still magnetic so they're not protected against big magnetic wave (e.g. from sun). There is an option to ...
10
votes
3answers
2k views

Why did expert systems fall?

Wikipedia gives a good summary of the AI winter of the late eighties and early nineties (the qualification is necessary since there has been more than one). Some aspects of it are clear enough, but ...
8
votes
2answers
955 views

In MS BASIC, why is NEXT faster than NEXT I?

I was reading over a thread on BASIC speeds on various home computers and noticed an interesting point that was not explained. Apparently, in MS BASICs, a loop using FOR I= ... NEXT will run faster ...
12
votes
7answers
1k views

Can I build a working(ish) vacuum tube byte?

This is a somewhat odd question. I teach a course on media history, and spend some time talking about digital data towards the end. I am interested in building a device to illustrate some basic ideas ...
11
votes
3answers
764 views

Why did CP/M require RAM in the bottom part of the address space?

A Z80 on RESET, starts executing from 0x0000. This is why the ZX machines and so many others have ROM at the bottom of the address space. Presumably an 8080 is the same. But as I recall, a CP/M binary ...
1
vote
2answers
269 views

How to replace battery for old AT mainboard?

On my 286 board, the CMOS battery is missing -- as with most boards of that age. I see no other battery connector on the board. However I would love to fit a battery in there, so I do not have to ...
11
votes
3answers
2k views

Were video chips specific to the CPU?

Modern graphics cards are essentially miniature supercomputers in their own right, with their own memory and instruction sets, but in the eighties and late seventies, a very common kind of personal ...
15
votes
1answer
681 views

How do Amiga “Monitor” drivers work?

A "Monitor" driver for an Amiga is a file which, when placed in DEVS:Monitors, enables additional screenmodes. The standard PAL or NTSC driver, which provides screenmodes compatible with consumer TV ...
4
votes
1answer
538 views

XT-IDE Universal BIOS does not find master drive on XT CF Lite card

I have built a XT CF Lite v4.1 to boot my 286 with a compact flash card. I have configured it via DIP switches to address 300h and I am using the XT-IDE Universal BIOS 2.0.0 beta 3. This is I think ...
3
votes
3answers
2k views

Reading both keyboard and joystick with non-KERNAL code on C64

I'm implementing non-KERNAL joystick and keyboard controls for my Commodore 64 game. I used to use the KERNAL SCNKEY routine earlier to read keyboard and it worked well with my joystick port 2 code. ...
4
votes
0answers
139 views

a learning gomoku in Lisp

Years ago I played a version of gomoku that was written in Lisp that learned as you played. After a few rounds, it became nearly unbeatable. This was on Unix System III on a small PDP-11. I have ...
8
votes
5answers
541 views

Where are the authoritative specs for legacy PC/AT devices still in use in today's PCs?

For example, the 8250/16550 chip used to handle serial communication is still simulated by modern chipsets and is enumerated by ACPI as PNP0500/PNP0501. You can find datasheets for these chips. ...
29
votes
5answers
7k views

Why was nil defined as a reserved word in Pascal?

In Pascal, nil (the pointer value to "nothing") is a reserved word. Why wasn't it simply a predefined identifier as true and false are, for example? This is stated in PASCAL User Manual and Report p....
10
votes
3answers
1k views

Intel 8080 - Behaviour of the carry bit when comparing a value with 0

I'm in the process of writing an emulator for the Intel 8080. The description of the CMP instruction from Intel's 8080 programming manual (see page 20) says the following: The specified byte is ...
2
votes
3answers
3k views

Game Boy save problem

I have an original Game Boy, and I know that saving is broken because Tetris won’t save my scores. How does saving work in Game Boy games, and are there any games that save without the use of the ...

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