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12
votes
1answer
505 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
372 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: ...
19
votes
1answer
531 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 ...
17
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
664 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, ...
14
votes
2answers
2k 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
557 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
503 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 ...
14
votes
2answers
783 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
718 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 ...
16
votes
1answer
3k 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?
24
votes
4answers
2k 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
228 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 ...
22
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,...
31
votes
3answers
3k 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 ...
9
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 ...
13
votes
1answer
547 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 ...
17
votes
1answer
973 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
196 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 ...
12
votes
2answers
681 views

Atari 800 CPU - 6502 vs. Sally

Regarding the Atari 800... What's the difference between the 6502A and the 'Sally'? Is it simply a revision, or do the changes improve performance?
19
votes
5answers
3k views

How can I power a C64?

I was chatting with our neighbor and after some long talking, I found out that he has a Commodore 64. I'd love to test it, however I'm not sure how to power it. How can I power a C64?
44
votes
11answers
6k views

What is the oldest computer capable of running a modern version of GNU/Linux?

A bit of a trivia question: What is the oldest hardware capable of running a modern Linux-based operating system, including user-space? (Not necessarily GNU userspace, but running a standard GNU/Linux ...
6
votes
3answers
407 views

What are the options for installing a 6309 in a TRS-80/Tandy Color Computer

The Hitachi 6309E CPU is a direct replacement for the 6809E in the CoCo. What are the options to upgrade to this processor?
10
votes
1answer
359 views

Differences in disk storage between systems

Coming from the TRS-80/TandyColor Computer lines, I had always heard of how slow some other systems disk storage were, regarding data transfer rates, etc... The CoCo lines disk storage was pretty fast ...
12
votes
2answers
719 views

Expansion port on the Color Computer

The Color Computer has an expansion port. What is the pin out? What are the kinds of devices that can be used with it? How was the Multi-Pak involved?
14
votes
3answers
1k views

How do I connect a modern display, keyboard, and mouse to a Power Macintosh 6100?

I recently got a Apple Power Macintosh 6100 for free. It powers up and seems to work, so I want to try it out and see what it's like. Unfortunately, the important ports and connectors are "non-...
47
votes
4answers
3k views

Why do older computer cases turn yellow?

Why do plastic cases of old computers turn yellow? Is this yellowing a problem that has been solved in modern plastics?
10
votes
3answers
599 views

How should I clean the plastic exterior of my computers and parts?

What is the most effective way to clean cases, keyboards, old calculators, etc. without harming or discoloring plastic finishes or printing/paint?
5
votes
2answers
272 views

Toshiba T2000SX can't boot from non-original HDD - “02” all over the screen

I used to have an old Toshiba T2000SX laptop, but some day its HDD died. I found a newer laptop HDD that fit in and I could format it to appear to have a small enough capacity to get detected by the ...
11
votes
1answer
410 views

What was the difference between CLOAD and LOAD “C:”?

8-bit Atari Basic had three different formats of storing programs on tape. CLOAD/CSAVE LOAD "C:"/SAVE "C:" ENTER "C:"/LIST "C:" I understand the specifics of the last one - it behaved as if the ...
10
votes
1answer
452 views

How does one convert Atari assembly to A=USR(ADR(“[garble]”)) style BASIC wrapper?

Some small utilities, tools etc for Atari were distributed as BASIC programs that would consist of just one line, that looked something like this: 10 A=USR(ADR("p$PHHLéúÿÿÇEéúÿÿ@éüÿÿ2A$éòùÿÿE°U´è§...
18
votes
2answers
993 views

What was the earliest non-valve, non-mechanical computer?

Just wondering how history questions will fare here. They could be a good addition to our scope. Pretty much exactly as the title says. Some of the earliest computers were based on valve systems or ...
12
votes
3answers
1k views

How did Atari cassette “turbo without hardware mods” work?

There were some cassette copying programs for 8-bit Atari, that boasted saving the games in a way that would load it at up to 1800baud - versus the standard 600baud, which was a significant ...
12
votes
1answer
420 views

How did the Lazer Systems Graphics Plus board work?

The first two Apple II models (the ][ and ][+) were unable to display lower case on the text screen. Some 3rd parties made lower-case adapters that replaced the character ROM (e.g. Dan Paymar's ...
23
votes
5answers
2k views

Did any Amiga 500 games or programs (apart from paint programs) use more than 32 colours?

While the Original Chip Set (OCS) and Enhanced Chip Set (ECS) Amiga computers had the 32 x 2 colour EHB (Extra Half-Brite) and 4096 colour HAM (Hold And Mofify) screen modes, where these ever used ...
11
votes
1answer
357 views

What format is used for CoCo cassette tapes?

Color Computer machines initially used audio cassette tapes for storage. How was the data stored? What was the maximum bit rate?
5
votes
1answer
160 views

What are these bus/tag connectors for?

I have a pair of connectors that mate with each other. One is labeled BUS, the other TAG. What are they for?
25
votes
2answers
1k views

Why does 6502 indexed LDA take an extra cycle at page boundaries?

On the 6502 CPU, this instruction: LDA $0380,Y takes either 4 or 5 cycles, depending on whether the indexing crosses a page boundary. But this instruction: STA $0380,Y takes 5 cycles regardless ...
7
votes
2answers
1k views

What format is used for Apple II cassette tapes?

Apple II computers initially used audio cassette tapes for storage. How was the data stored? What was the maximum bit rate?
9
votes
1answer
151 views

Is there way to save the save state?

I found my Game Boy Advance in a box a few days ago, and I'm already playing good old Mario games. The problem is that I usually don't have time to finish the whole level at the same time (or I might ...
21
votes
3answers
2k views

How can I overclock my Commodore 64?

My Commodore 64 is running quite slow, and my friends want it to be faster, thus overclocking it. But no one knows exactly how to do that. With our current "modern" stuff, nothing seems to help my ...
28
votes
2answers
19k views

GameBoy Color games do not save any more

I have a Nintendo GameBoy Color with some games that support saving your game status and also have a real-time clock, like Pokémon Red and Pokémon Silver. But recently the game does not save any more,...
12
votes
1answer
582 views

Dumping and sharing software for old Sharp calculator

I have an old programmable Sharp calculator (Sharp EL-9000 SUPER SCIENTIFIC) which I used extensively back in the day. I would like to dump all the software I wrote, and be able to share it. I ...
18
votes
1answer
2k views

Change Amiga Shell keyboard layout in Workbench 1.3

I'm using Workbench 1.3 in Amiga 500. I managed to change the Spanish keyboard in "SetMap", as shown in the following figure: And I can write text with special spanish characters (ñ,ç,ó,á,...) from ...
12
votes
2answers
858 views

How can I rejuvenate Game Boy contacts? [duplicate]

I've got an old Nintendo Game Boy, with a number of games for it. The problem is that most of these games don't load any more, and I suspect that's an issue with the contacts either in the unit, or in ...
33
votes
3answers
5k views

What modification is required from a PC floppy for use in Amiga?

Around the end of the time of Amiga popularity, obtaining a replacement Amiga floppy drive was a nuisance, while PC drives were ubiquitous and cheap. One could install a PC drive in Amiga after ...
17
votes
9answers
1k views

Were there any commercially available graphical interfaces before the apple Lisa?

I just finished the Steve Jobs biography and I thought... Was the apple Lisa really the first commercially available Graphical interface? This is just out of interest but I'll be really interested ...
10
votes
1answer
469 views

How many analogue RGB signal levels did the VIC-II have?

Although only 16 different colors were allowed on c64 (more exactly, in the VIC-II), which came from a fixed palette, the video output created an analogoue tv signal. Which means, somewhere in the ...
17
votes
1answer
739 views

How to move sprites to the border on c64?

As far as I know, there is no register in the VIC-II, which would enable this. Despite that, in nearly all intros and in many cases even in old games, sprites on the border were visible. Actually, it ...

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