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23
votes
1answer
1k views

Why are there two, different, Kickstart 1.3 ROMs with the same 34.5 version number?

The Kickstart 1.3 ROM file that is supplied with Cloanto's Amiga Forever (amiga-os-130.rom) is very slightly different to that which you'd get by dumping a real 1.3 ROM from an Amiga 500. ...
4
votes
1answer
141 views

How do I replace the battery on my Palm Zire 21?

My Zire 21 PDA's battery won't hold a charge for more than a few minutes. How do I replace it?
17
votes
1answer
790 views

Motorola 6809 Stack Blasting

I've seen several mentions of a "Stack Blasting" technique for copying memory quickly on the 6809. What is it? How does it work?
7
votes
1answer
91 views

How to measure time with frame resolution or better using BASIC in an Oric Atmos 48K

Following in the line of this question How can you measure time using BASIC on Atari XL computers? I'd like to ask how can you do the same (measuring time, with a resolution of frames or better if ...
12
votes
3answers
401 views

Pair Am386 with i387

I've got a motherboard with a Am386/DX processor. I've also got an Intel 387 coprocessor. Is it possible to use the Intel 387 that I've got together with the Am386 or do I need a coprocessor from AMD?...
11
votes
1answer
728 views

How are held-down keys handled in CHIP-8?

The CHIP-8 has, among its instructions, the following ones: Ex9E: Skips the next instruction if the key stored in VX is pressed. ExA1: Skips the next instruction if the key stored in VX isn'...
22
votes
2answers
951 views

How can I programmatically tell which version of Apple II my code is on?

There are minor and major differences between the many Apple II models. I would like to detect whether my 8-bit assembly language program is running on a II, II+, IIe (enhanced or not), or ///, and ...
8
votes
1answer
386 views

Cleaning membrane keyboards

I have a 3003b CoCo 1 (the white one) with the melty keyboard. A few of the keys do not work. On a few of them, there appears to be a slimy substance that I've cleaned from the surface. The badge on ...
17
votes
1answer
1k views

How did the Epyx Fast Load cart work with a Commdore 64?

Why would adding a cart in your system suddenly speed up the C64 or the 1541 for loading games?
17
votes
2answers
2k views

Can I run a NES emulator off the original cartridges?

Every NES emulator I've found runs off ROM dumps. Would it be possible to run an emulator using the original cartridges directly? It's probably not the most practical way of doing things, but the "...
15
votes
1answer
762 views

How was 8-channel audio achieved on Amiga?

Oktalyzer was a Tracker style program for Amiga, that allowed composing and playing music with 8 channels instead of the "hardware-natural" 4. So far I learned it achieved that by splitting the 4 8-...
15
votes
1answer
2k views

How could Amiga computers play 14 bit sound?

The "Paula" chip used for sound output in all Amiga computers had 4 8bit sound channels (arguably comparable to 9bit stereo). There were programs/libraries which could play 14bit stereo on the Amiga ...
7
votes
2answers
143 views

Disto Super Controller II

A popular third party floppy disk controller for the Color Computer was the Super Controller II from Disto. It's main feature was a no-halt mode. Why was this desirable? How did the no-halt mode work?
9
votes
2answers
291 views

Information about Sabre-ADS Model 757 terminal

Someone on reddit acquired a Sabre-ADS terminal, Model 757. They were used for airline reservation and probably connected to an IBM mainframe. Is there anything known about the pinout and workings of ...
17
votes
2answers
694 views

Color BASIC RND function not so random

The RND() function for random numbers appears to give the same results each time the computer is reset. How do I seed the random number generator with a random number?
22
votes
3answers
3k views

How was digital sound playback achieved on the Commodore 64?

The Commodore 64 did not have any hardware dedicated to digital audio playback, so how were some games and songs able to achieve this on an unmodified and unextended Commodore 64? Did these ...
18
votes
1answer
782 views

Any difference between a VIC-1541 and a C64-1541?

I have both a beige VIC-20 styled VIC-1541 disk drive and the later brown C64 1541 drive. Is there a difference between them (besides how they look)?
10
votes
1answer
189 views

CoCo Max Mouse Cartridge

The program CoCo Max came with a cartridge. The cartridge had a mouse/joystick port. How did the CoCo Max Analog to Digital cartridge work? Is it possible to use the device in my own software?
8
votes
1answer
757 views

Commodore 64 with partly working keyboard

My Commodore 64 has developed a fault with the keyboard. Some of the keys are working and some aren't. As far as I can see there is no pattern and they are randomly distributed across the keyboard. ...
16
votes
1answer
783 views

Why is the Apple II hi-res HGR command so slow?

The Apple II hi-res screen sits on 8KB of memory, so it should be possible to erase it quickly. The Applesoft HGR command is slow enough that the "Venetian blind" erasure is clearly visible. ...
32
votes
5answers
2k views

Why did the Bell 103 modem use a data rate of 300 bps?

Virtually every telephone modem in existence runs at a data rate that's a multiple of the Bell 103A's 300 bps. Why was the base 300 bps chosen in the first place?
5
votes
1answer
101 views

Extended Color BASIC TIMER Function

How does the TIMER function work in Extended Color BASIC? How does the number keep incrementing even when the computer appears to be doing nothing?
28
votes
1answer
2k views

How does the command.com shell work with MS-DOS?

On my systems that are running MS-DOS, I change the default command.com to 4DOS for more features. How was the shell system designed and how did it with the operating system in MS-DOS that it enabled ...
12
votes
2answers
500 views

What did disk-validator do?

...besides relabelling the disk to 'Lazarus' and helping the Saddam virus spread? I know it was supposed to 'fix' corrupted disks that were ejected during a write operation. I don't think I've seen a ...
10
votes
2answers
395 views

Acorn Electron fails to load .UEF files converted to .WAV

I have an Acorn Electron that came without tape recorder, so I'm using Audacity to record and replay programs which works fine. Now I also have some software as UEF (Universal Emulator Format) files. ...
12
votes
1answer
220 views

Is my Atari Falcon's filesystem messed up?

I use the Cecile driver for the Kingspec DOM (basically an IDE flash drive0 in my Atari Falcon. I've noticed on occasion that in file dialog boxes (save, open etc.) I sometimes see weird files, called ...
19
votes
1answer
660 views

How did XBAND modems transmit game state?

The XBAND Video Game Modem and Network allowed owners of Sega Genesis and Super Nintendo game systems to play head-to-head over a phone line in 1994, before "twitch" gaming over the Internet was ...
10
votes
2answers
276 views

How to bring up the firmware console on a SunBlade 100

I've got an old SunBlade 100 workstation that I'm trying to install OpenBSD on. The first step in the process is to bring up the OpenFirmware prompt to select the boot medium, which you do by ...
16
votes
2answers
515 views

Atari 2600 paddle controllers slow, jittery

I recently picked up a pair of Atari 2600 paddle controllers for use with my Atari Flashback 6. The Amazon store said in the product description that they had been "tested." However, they are barely ...
16
votes
4answers
395 views

What was the first intentional malware that got spread over multiple machines?

I would like to know which program can be seen as the first malware. To define the term "malware" in this question, I would suggest those criteria, but you may modify them if you feel the need: real ...
13
votes
1answer
561 views

What does Personal Paint documentation actually refer to by “unmaskable interrupt” for its “crash protection feature”?

Personal Paint was a gfx program for Amiga that introduced many novel concepts, some quite ingenious, some... controversial. Among all, it had a "crash protection" feature, that was meant to enable ...
17
votes
2answers
465 views

How can you measure time using BASIC on Atari XL computers?

Some time ago, I benchmarked some 8-bit computers to find out the fastest BASIC interpreter. I ended up using the classic SAXPY benchmark, as I didn't want any I/O overhead to fool the measurement: ...
20
votes
1answer
612 views

What did the cassette bootloader in 8 Bit Ataris do?

...or for that matter, what didn't it do, so that you'd use the "bootloader/main program" separation instead of loading everything at once. Normally, when loading games or any non-BASIC software from ...
19
votes
2answers
1k views

How did programs/patches stopping Amiga idle floppy drive noise work?

The Amiga computers would by default automatically detect a disk being inserted and respond by reading from it and displaying its icon. Polling the drive(s) for a new disk would produce a clicking ...
15
votes
3answers
781 views

Atari 800XL showing a red screen

My friend has a Atari 800XL in mint condition. When the device was turned on, the only thing that appeared was a dark red screen. Another friend of mine figured that the memory chips were to blame, ...
16
votes
2answers
3k views

Booting an Amiga 1000 directly to the hard drive without Kickstart floppy

The Amiga computers such as the Amiga 1000 required a Kickstart floppy to be able to boot directly into a hard drive. I have a Amiga 1000 as well but missing the Kickstart floppy. I would like to ...
3
votes
1answer
594 views

Why won't the game “Ultima I” work on my Apple IIe system? [closed]

I'm trying to complete the original Ultima I on an Apple //e. These instructions explain space flight, but I can't seem to destroy enemy ships in order to become a Space Ace, even when I should be ...
18
votes
2answers
575 views

What are the common sources of incompatibility on different MSX computers?

I remember that a LOT of games for my MSX (I live in Brazil) don't work without some modification. For example, several need some kind of tweak on the loader, like poke -1,0. I would like to know ...
15
votes
2answers
927 views

What information is encoded in the 22-digit barcodes on the Amiga's case?

What information is encoded in Amiga's 22-digit barcodes? For example: 0103791363642010121234
18
votes
2answers
887 views

Comprehensive test suites for MOS 6520 PIA / 6522 VIA / 6526 CIA

Are there any automated test suites for MOS 6520, 6522 and 6526 chips? I am looking for test suites aimed at making sure datasheet-based independent reimplementations of the above chips (e.g. FPGAs or ...
18
votes
1answer
4k views

Is it possible to use an Amstrad CPC464 with a modern monitor or TV

During a recent move I lost the monitor for my Amstrad CPC464. Is it possible to adapt the output of this to work on a modern monitor or on television set?
30
votes
5answers
3k views

What were the differences in floppy disk formats between Amiga and IBM/PC compatible computers?

The capacity in Amiga Old File System format (OFS, OS version 1.x) was 840KB, with the Fast File System ("FFS" (!)) introduced for OS 2.x onwards able to store 880KB. The PC format stored 720KB on the ...
14
votes
1answer
249 views

Inserting NOPs to improve IIgs shadow copy performance

The answer to this question discussed a technique on the Apple IIgs for copying memory onto itself. The motivation for the technique was to maximize use of "fast" (2.8MHz) RAM over "slow" (1MHz) RAM ...
23
votes
5answers
2k views

How much benefit should be expected on a more advanced compiler for z80/r800 based computers?

I am self studying about compilers, and get hands on very good textbooks about the subject. I am thinking in develop a compiler using the almighty llvm infrastructure to cross compile to old computers,...
32
votes
3answers
4k views

80286 can switch from real mode to protected mode - but why not back?

It's been a while, but I've read in a system programming book that you could switch your Intel 80286 CPU from the normal real mode to a more powerful protected mode. I clearly remember that they said ...
10
votes
3answers
1k views

What format is the (Timex) Sinclair ZX Spectrum SCREEN$/.SCR file

What format is the (Timex) Sinclair ZX Spectrum SCREEN$/.SCR file and how is the fore/background and attribute data encoded within this format?
24
votes
3answers
2k views

Linux 68k Macintosh emulator

I'm currently using the absolutely ancient "Fusion" emulator to emulate a 68k Macintosh (specifically, a Quadra 700), but it only runs under MS-DOS, so I'm using a VirtualBox VM to emulate that. I'd ...
17
votes
1answer
663 views

How can I interface with an old Atari from a modern computer?

I have an old 8bit Atari at my dad's house which would be fun to play with. It has a keyboard, computer and screen, turn it on, and program BASIC. But I'll possibly want to load the code from a ...
18
votes
1answer
1k views

What size screws were used in the Amiga desktop cases?

On the Amiga 500, 500+, 600, and 1200, what size screws were used to hold the chassis together? Is it the same size screw for all, different screws per machine, different screws front and rear, or ...
6
votes
2answers
288 views

How do I interpret the old Mac character set?

Older Macintoshes and the Apple IIgs used a custom character set for documents and filenames. Each character was held in an 8-bit byte, using 0x00-0x7F for ASCII, and 0x80-0xFF for various symbols ...

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