All Questions

12
votes
1answer
369 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
292 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
149 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?
23
votes
2answers
975 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 ...
8
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
139 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 ...
27
votes
2answers
12k 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,...
13
votes
1answer
467 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 ...
17
votes
1answer
1k 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
574 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 ...
32
votes
3answers
3k 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 ...
14
votes
5answers
738 views

Was 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
432 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
620 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 ...
14
votes
2answers
672 views

What is this code on the zero page that was put there by the BASIC ROM?

(question copied from SO (from the days before RC.SE existed): http://stackoverflow.com/q/31877835/477476) Zero-page memory maps of the PET that I've found claim that the zero page address range$00C2....
22
votes
5answers
2k views

How do you open an SE/30? (a.k.a. what is a “pull-apart tool”?)

I have been trying to work out how to open a Mac SE/30, in order to have a better look at its internal condition. I have the repair manual, and in the "Take Apart" section it references a "pull-apart ...
11
votes
1answer
357 views

What's the difference between DOS-ordered and ProDOS-ordered disk images?

Apple II emulators accept disk images in "DOS order" or "ProDOS order". What's the difference? Why have two different formats?
6
votes
2answers
179 views

Will an eMac boot without a PRAM battery installed?

eMacs have a 3.6V PRAM battery and some sources indicate that when the voltage starts to drop that they may have trouble booting. Will an eMac work without a battery?
7
votes
1answer
120 views

How do you remove the clear section from the back of the eMac's housing?

As the title states, the eMac has a clear section at the back of it's housing that forms a grill for the fan inside. This seems to be pretty good at catching dust that's impossible to get at simply by ...
10
votes
1answer
460 views

My Compaq Presario CDS 633 outputs color in Windows 3.1 but not in DOS. How can I get color in DOS?

My Compaq Presario CDS 633 outputs color in Windows 3.1, but not in DOS. How can I get color in DOS? I have tried the MODE setting, but it did not change anything. ANSI.SYS also has a LOADHIGH line ...
25
votes
3answers
1k views

What are the differences between a PAL and NTSC C64?

A lot of programs released for the Commodore 64 contained different software for the PAL or NTSC computer. Why did they have different versions of the hardware? Did the software have to be different ...
18
votes
3answers
1k views

How did “full memory” Spectrum tape copiers work?

There are some tape copiers, such as LERM that claim to be able to copy tapes which contain software that takes the full 48kbyte of RAM. However, this seems impossible on a Spectrum, when the whole ...
21
votes
2answers
537 views

How do I use shadowed memory to render Super Hi-Res quickly?

The Apple IIgs video memory is controlled by the 1MHz Mega II chip, so directly accessing the Super Hi-Res page in bank $E1 is slower than accessing other memory. How can I render in "fast" memory, ...
22
votes
2answers
1k views

How to obtain 256 arbitrary colors with limitation of 64 per line in Amiga (ECS)?

The game Universe for Amiga boasted ability of use of 256 different Amiga colors available through the ECS chips, with only limitation of 64 colors in halfbrite palette (32 arbitrary + 32 at half ...
23
votes
3answers
2k views

Adapting a “modern” keyboard to a ZX Spectrum

Is there a way, such a specific interface adapter, which would allow me to connect a PS/2 keyboard to an original ZX Spectrum? I expect the keyboard to work similarly to the ZX Spectrum itself -- in ...
18
votes
1answer
755 views

How does the 4MB mod for 8-bit Atari work?

On the local auction portal I have spotted ads for some "supercharged" 8-bit Ataris (800XL, 65XE etc) - modified to support 4 megabytes of RAM. The auctions were scarce in details, more concentrating ...
27
votes
1answer
1k views

How does “bit-slip” copy protection work?

Some Apple II 5.25" floppies used a special pattern of bytes that could not be automatically detected by disk copying software. How could the pattern be invisible to disk copiers but detectable by ...
15
votes
3answers
2k views

With a 15 kHz video signal (240p or 480i), does VGA have any real-world advantage over S-Video?

It's difficult to find a modern LCD monitor that can display a 15 kHz signal through VGA, so I'm wondering if S-Video is just as good when displaying 240p and 480i? I've looked at screenshot and video ...
20
votes
1answer
2k views

How to convert Amiga DMS to ADF?

Our demoscene group managed to release only one demo before it fell apart, but these being the early days of the Internet in my country, and me getting lucky with obtaining access to it and creating ...
20
votes
2answers
1k views

Cleaning 5¼" floppy drives

Going to the store is treacherous for me. So I prefer doing stuff at home, including cleaning up 5¼" floppy disks with only home supplies. Unfortunately, I do not know how or which materials/chemicals ...
17
votes
2answers
794 views

Transferring from Apple II

I have also found a working 1978 Apple II. Now my dad wants me to transfer its data to another device without using fancy Apple II exclusive hardware and if possible, through a cassette port. Now, ...
10
votes
1answer
463 views

How to convert Atari (65XE) tapes to ATR?

I still have some tapes for my Atari 65XE and I'd like to play some of the old games I got. But I don't have the Atari anymore. I have a tape recorder of quality surpassing the Atari one by quite a ...
33
votes
3answers
1k views

Advantages of a Hitachi HD6309 versus a plain Motorola MC6809

Hitachi was a second source for the Motorola 6809 Micro Processor. The 6309 had many secret features. What advantages does the HD6309 have over the MC6809?
17
votes
2answers
573 views

What should I do when some of the keys of my Amiga 600 have stopped working?

I opened up an Amiga 600 to install a hard drive, and after reconnecting the keyboard ribbon and powering the computer up, at least one column of keys no longer works. What did I do wrong and what ...
10
votes
1answer
138 views

What to replace the belt in the cassette drive of an Epson HX-20 with?

I am the owner of an Epson HX-20 laptop computer. It runs well except for the builtin cassette drive which doesn't seem to work reliably. After carefully disassembling it I found that the belt seems ...
19
votes
3answers
966 views

Documentation for the ZX Spectrum ULA

I am writing a Spectrum emulator, however I am finding it difficult to find official or reliable information about the ULA, its functioning and its pins. Are there official sources documenting its ...
15
votes
4answers
914 views

Powering up my ZX Spectrum

I have also found a nice ZX Spectrum laying around. It needs a power source of course to run but there seems to be none that can be used to power it. Google doesn't seem to help and I would love to be ...
10
votes
1answer
172 views

How do I change the CoCo 3 color palette before running a Color Computer ROM Pak?

The Radio Shack game Wildcatting uses the wrong color set when being played on a Color Computer 3 with an RGB monitor. How can I choose the correct color set before this game automatically executes?
29
votes
6answers
916 views

Dumping and archiving C64 disks

Doing spring cleaning with family, I found some old C64 disks. These are really old and no one knows what to do with them. Archiving or dumping them seems to be options but we are unsure how to do so ...
33
votes
3answers
3k views

Reconditioning and cleaning old Nintendo (and other) game cartridges

I used to blow the dust out of the cartridges but I heard that can actually damage the cartridge or the system itself. I am looking for the proper way to clean old Nintendo game cartridges (such as ...
20
votes
3answers
465 views

Where can I find software for the PDP-6?

We are planning to build a reconstruction of the PDP-6. The project is making a lot of progress, but currently we have a critical lack of software. Does anybody know where we can find software to run ...

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