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2answers
38 views

What are D64, T64, D71 and D81 files?

The docs for Ultimate-II+ expansion cartridge for the Commodore 64 state: It is able to read D64 files, as well as D71 and D81 files (no partitions), T64 files. So what are D64, T64, D71 and D81 ...
0
votes
0answers
38 views

Access to Internet from old devices (HTTPS, SSL, certificates, compatible services,…) [closed]

I find information and resources about connecting 18-12 years old devices to Internet, specially PDAs and phones. I am also interested in computers but they will have less limitations and issues, as ...
-1
votes
0answers
78 views

Why fight the protocol wars? [closed]

There is a well known war in computer science that involves a lot of its domains: The Protocol War (https://en.wikipedia.org/wiki/Protocol_Wars). I would like to know, what was the reason companies ...
3
votes
1answer
40 views

Converting Apple II ProDOS blocks to DOS tracks and sectors

The 8-bit Apple II had two disk operating systems with different disk access semantics. DOS used tracks and sectors. A sector is 256 bytes. ProDOS used blocks. A block is 512 bytes. But mapping ...
7
votes
2answers
664 views

How can I programmatically determine whether an Apple II .dsk disk image is a DOS .do image or a ProDOS .po image?

I'm interested in working with the most common Apple II disk image file format, .dsk. (I only programmed these machines briefly in Basic around 1979-81 and have not been in the emulator scene, so I'm ...
-2
votes
2answers
161 views

What’s the last x86 CPU that didn’t place a limit on the size of a single instruction?

Although useless, it’s widely known the first Intel and derivative CPUs like the Z80 didn’t set a limit on the instruction size. This means that it was possible to fill the whole RAM/ROM with a single ...
1
vote
4answers
351 views

Is this a computer screen in 1956, and if so, what is it displaying?

The photo below shows what may be a CRT for the TX-0 (transistorized experimental computer) in 1956, referring to what may be a CRT on the left side, not to the CRT on the right side . If that is a ...
1
vote
0answers
97 views

Did the Mega Drive and/or Arcade version of the song “Afterburner” use FM synthesis or samples?

Does anyone know if the Mega Drive or Arcade version of Afterburner use FM synthesis or sound samples for orchestra hit in its song "Afterburner". I find oscilloscope views of each version but I'm not ...
2
votes
1answer
155 views

Is this real Commodore C386SX-LT

Is the model shown on pictures an authentic Commodore C386SX-LT? Why does it look different to other photos on the Internet (some additional grey keys? above keyboard): http://www.spacereh.de/hc/com/...
2
votes
2answers
108 views

HDD data recovery advice

I found my assumed long lost “win98” toshiba protege laptop in our wet and moldy storage container. Was there for years, through cold-humid variances. The files on his computer are extremely ...
12
votes
2answers
3k views

How do C64 cartridges swap running programs without losing state and context?

I recently picked up a 1541 Ultimate II+ for my Commodore 64 and have been amazed at how this device seemingly can do every flash memory and other enhancement feature for the machine, short of CPU ...
7
votes
5answers
2k views

Connect Ethernet via Parallel or Serial in old laptop

Is it possible to connect an old 386 machine to network (ethernet)? It has only parallel and serial ports. I'm not expecting much, just planning to use it as a remote terminal. The machine in question ...
3
votes
1answer
62 views

Do TRS-80 Model I and Model III load and execute /CMD files using specific memory addresses?

/CMD files on the various TRS-80 Model I and III OSes are machine code command files. They seem to have some internal format but not really a file header. They often start with 01 02 and then a 16-...
1
vote
1answer
139 views

Connecting analog pedal from sewing machine to computer audio jack [closed]

I got a control pedal from an old sewing machine that connects to a 3.5mm jack. It fits in the audio/microphone jack of my laptop. Is there any way that I could detect from the laptop this pedal ...
5
votes
2answers
145 views

How to get out of Apple IIe mode on Macintosh Color Classic?

I just picked-up a Macintosh Color Classic with an Apple IIe card. I've never used one of these before but was able to get it to enter into Apple IIe mode. However, I cannot seem to figure out how to ...
12
votes
1answer
2k views

How can Windows 98 shut down in less than 5 seconds?

I have used Windows 98, and observed that its shutdown is very fast. How is that?
9
votes
1answer
87 views

In TRS-80 parlance when talking about disks, what are “granules” and “lumps”?

In my reading to try to learn about the disk layout, directory, and boot process of TRS-80 Model I and Model III, I see some unusual words come up again and again. Along with the common terms "track" ...
33
votes
7answers
5k 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
1answer
108 views

What is the file that VICE refers to as dos1541?

VICE needs a file called dos1541 if you want hardware emulation of the 1541 disk drive. What does that file contain, exactly? The 1541 seems to have two ROMs: a DOS and a KERNAL. But if I take the ...
3
votes
1answer
70 views

What is the process for TRS-80 Model I & III to boot from disk?

I can find enough mentions of bootable disks for TRS-80 Model I and Model III to be confident that they could boot from disk, but so far I'm failing to find much info on how that worked. In ...
2
votes
1answer
84 views

How was the second bank of Apple IIc ROM accessed?

The original Apple IIc had a 27128 16 KB ROM mapped into the $C100-$FFFF range (the $C000 page was decoded for I/O). According to the Apple IIc Technical Reference Manual the ROMEN1* and ROMEN2* ...
1
vote
0answers
23 views

What is the layout of the directory track on a TRS-80 Model I/Model III disk?

I've decided to add support for some more classic Z80 computers I used to use to my Ghidra modules, and the first Z80 systems I used were the TRS-80 model I and model III. I've found documentation ...
5
votes
1answer
171 views

What is the format of the static libraries shipping with legacy Microsoft C for DOS?

I have installed Microsoft C 5.10 on DOS 6.22. It created a 'LIB' directory with static libraries to link against. Now I need to extract the symbols and the code for the functions from them, but can't ...
4
votes
3answers
117 views

The 8086 has AAM (ASCII Adjust after Multiply), why not the same for packed BCD?

I'm just curious why the 8086 seems to be lacking in an adjust opcode for fixing up packed BCD multiplication. It seems like it would be a useful thing, and packed BCD seems to be more common to begin ...
3
votes
1answer
183 views

Windows NT 3.51 title bar buttons

What is exact meaning Windows NT 3.51 title bar buttons? Arrow up is maximize and arrow down minimize? And left button is close? Its my assumption right?
2
votes
1answer
86 views

Auxiliary Carry and the Intel 8080's logical instructions

I'm trying to figure out how the Auxiliary Carry flag on the 8080 is affected by logical instructions. Reading the Intel 8080 manual, it seems that logical instructions do not affect AC: The ...
1
vote
3answers
106 views

How to determine where in RAM the current Basic program resides on Amstrad microcomputers?

How can I find where in memory to locate the current Basic program in an Amstrad CPC/PCW family Zilog Z80-based microcomputer? Is it always the same address? A different well-known address depending ...
3
votes
2answers
82 views

Is there a “most correct” name for the disk format / filesystem used by Amstrads and Spectrum +3's?

The native floppy disk format/layout or "filesystem" used by Amstrad microcomputers such as the CPC and PCW range and by the Sinclair Spectrum +3 are versions of one that came from CP/M. In Amstrad ...
0
votes
0answers
59 views

When did file based communication / design patterns became obsolete in enterprise applications? [closed]

Short story I am curios about when file based communication / design patterns became obsolete in enterprise applications. Although I have been programming for more than 15 years at enterprise level, ...
0
votes
3answers
219 views

How do multi-byte instructions work?

Let's say you have a hypothetical 8-bit processing machine with 256 bytes of memory. You want to load the value stored in memory location $f2 into a register. However, with a data bus of just 8 bits, ...
4
votes
1answer
104 views

Why is my Macintosh LC 475 playing chimes of death when I install more ram?

I bought an LC 475 for parts and repair on ebay. When it arrived it seemed to work okay but the video was all stripey. After some diagnosing I spotted a rotten trace near the the VRAM simms. I ...
-4
votes
1answer
89 views

What's the name and model of this computer monitor?

It's look like very old thing to me: It's in Black and White display. As you can see, it has a socket on the top of it . What's the name and model of this computer monitor?
12
votes
2answers
1k views

Should I use the internal or external drive for loading Amiga 500 games?

I have a working (I think) Amiga 500 system with an internal DF0 drive and an external DF1 drive. The Amiga 500 powers up with Workbench v1.3. Can anyone tell me how to access a game disc (Marble ...
5
votes
0answers
164 views
+50

What are the needed jumper settings for a 68060 accelerator for an Amiga 3000T?

I'm trying to install a 68060 accelerator on an Amiga 3000T, but I cannot figure out the correct jumper settings. The information I've found online is: J100 CLK90 Delay jumper. This Jumper has three ...
2
votes
1answer
67 views

Are the last 4 bytes in .SCL disk image files for Spectrum clones meaningful or spurious?

I recently added support for .scl images files to my Ghidra module which already supported .trd images. They are both representations of TR-DOS floppy disks as used mainly on Spectrum clones from ...
1
vote
0answers
91 views

Why did the Spectrum Next choose Z80 on FPGA? [closed]

I'm curious to understand why the Spectrum Next uses Z80 on an FPGA instead of something like at eZ80? I would have imagined they would choose the eZ80 since it is still a production part. Anyone ...
27
votes
14answers
6k views

History of non-American software/hardware/CS theory development, 1940s-1980s?

I am curious to learn about any developments in computer theory, hardware, and software that took place outside of the United States, in the middle of last century (~1940s-1980s). I have read 'Where ...
34
votes
8answers
7k views

When and why did high-level language compilers start targeting assembly language rather than machine code?

From what I've read, the first FORTRAN compiler built a machine-code program entirely in memory; it was, in fact, designed to read the entire source code of the program, and then sequentially load ...
4
votes
4answers
328 views

Would having the console's CPU help in emulation hypothetically?

If I had a hypothetical computer just like nowaday's computers, but it had an NMOS 6502, would it provide me with a better emulation experience than if I were to emulate the 6502 inside software? Also,...
8
votes
3answers
382 views

Did the 6502 need both ADC immediate and SBC immediate?

The 6502 uses the carry bit system (over a borrow bit). On such machines, the bitwise NOT is applied to the subtrahend before it is "subtracted" (really, added, taking advantage of two's complement) ...
13
votes
2answers
3k views

In 2020 are there fully assembled z80 devices available at reasonable cost? [closed]

I'm wondering if it is possible to buy an sort of device currently in production that uses a z80 compatible CPU - not an FPGA. I don't want to build a kit or use a soldering iron. I'm also looking ...
9
votes
2answers
1k views

What was the first preprocessor for a programming language?

A preprocessor is a tool that takes source code as input and outputs a modified version of it for input to a downstream tool, such as a compiler or interpreter. Preprocessors can be used to implement ...
4
votes
1answer
190 views

How does the “Small fire-Mario” glitch in SMB1 work?

There's a glitch in the original Super Mario Bros., that causes Mario to become an unused sprite(Small Fire-Mario). I'm unsure how the glitch works, but I'll show the instructions on how to pull it ...
67
votes
3answers
17k views

Why does part of the Windows 98 Setup program look older than the rest?

When installing Windows 98, the part of the setup process where you enter things like product details looks... different. The scrollbars, buttons, title bar and such look more like they belong in ...
1
vote
1answer
152 views

Is the 1920 CTR Printer-Lister a Ticketograph?

In an answer about screen formats Raffzahn wrote: "In 1920 the Tabulating Machine Company (originally The Hollerith Electric Tabulating System, now part of CTR Holding) introduced a new printer-...
40
votes
4answers
8k views

Is it true that Pentium III was faster than its successor Pentium 4?

My friend told me that earlier iterations of the Pentium 4 were not as fast as the Pentium III, but he didn't have sources. Is it true that the Pentium III was faster than its successor Pentium 4?
3
votes
2answers
136 views

How to get into Apple BASIC prompt on an Apple IIc?

I just picked up a used Apple IIc. For some reason all I get when I boot is Check Disk Drive on the screen, even with a bootable disk in the internal drive: I cannot even get the system to read the ...
7
votes
2answers
142 views

How long should I expect the Apple IIc self test to run?

I purchased a vintage Apple IIc computer and I want to make sure there are no failing components. I booted up the computer while pressing both Apple keys (open and close) at the same time. The ...
5
votes
3answers
359 views

What were the Major Public Access Unix Systems Available in the 1980s-90s?

Back in the 1980s-90s, using a UNIX system required running expensive servers or paying for timesharing service, so they were beyond the reach of most individuals, and only available to members in ...
45
votes
2answers
10k views

Why does the 80486 take longer to execute simple instructions than complex ones?

The 80486 processor can execute many instructions in a single cycle, such as a register-to-register add instruction (ADD EAX, EBX, for example), which one would generally assume is fairly complex, ...

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