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11
votes
4answers
3k views

Is there any way today to recover/dump 2M disks?

2M disks where formatted using 2MGUI to increase 3"1/2 & 5"1/4 DD/HD/ED disks' capacity. Is there any way today to recover/dump these disks to a file with modern hardware? Specially the 5"1/4 ...
5
votes
1answer
265 views

How can I change the MSX function keys using ASM?

How can I change the texts assigned to MSX function keys using Z80 ASM?
2
votes
1answer
148 views

What were Commodore's keyboard layouts before the VIC-20?

Starting in 1980 the VIC-20 keyboard seems to have become sort of a standard for Commmodore, being re-used on the MAX Machine (in membrane form), C64, C16 and (with additional keys added) the 128. ...
1
vote
3answers
208 views

Was 1.10 a valid line number in FOCAL?

I'm looking over examples of FOCAL code, and I see that group numbers in the examples start with a 0 if need be. That is, it's 01.10, not 1.10. Was a leading zero optional?
27
votes
2answers
10k views

Looking for PC graphics demo software from the early 90s called “Unreal”

Back in the early 90's I remember downloading a graphics demo called, I think, "Unreal". This was on DOS on a standard PC and probably downloaded from a BBS. Identifying information: It ran for ...
8
votes
4answers
509 views

Which cartridges were typically used together on Commodore 64 systems?

It's possible to extend the Commodore 64 expansion port bus with boards like the [Aprospand-64]: This example dates from 1986, but there appear to have been a number of contemporary expanders, and ...
15
votes
6answers
5k views

How slow was the 6502 BASIC compared to Assembly

Imagine a modern computer, where let's say Python is a high level programming language and needs to be interpreted in order to execute a piece of code. You could write some code in C, compile it, ...
20
votes
3answers
2k views

What does it take to recreate microchips like 68000 and 6502 in their original process nodes nowadays?

I am trying to figure out what type of machines could be used to reconstruct these chips nowadays. It doesn't need to use exactly the same machines used to build them, it's just that the product ...
1
vote
3answers
405 views

What was the distinctive rapid clicking sound in late 1990s desktops?

I am fairly sure that this clicking wasn't just because my computer had issues, although that would be interesting to find out. I distinctly remember that the first computers I owned would make a ...
4
votes
1answer
129 views

Looking for an IBM multimedia demo from the 80s about “Ulysses”

I am trying to identify / find an online copy of a multimedia technology demonstration video. Timeframe: late 1980s? Source: IBM. Format: VHS. The content of this video was a computer program with a ...
5
votes
0answers
86 views

IBM terminal schematics

I'm searching for the electronics schematics for IBM terminals 3477 and 3486. I've already googled for it without success. I've to mend this hw and the power side seems ok but doesn't function, so I ...
3
votes
2answers
355 views

How did computers generate 'noise' sound files?

I figured out how to make square, triangle, and sawtooth waves in pygame. However, I have no clue what kinds of waves I need to make to produce a 'noise' sound effect like you see in older computer ...
11
votes
3answers
2k views

Was there an autocomplete utility in MS-DOS?

MS-DOS (at least 6.22) had optional features such as DOSKEY to remember the command line history, which is now standard on modern command prompts. However, I'm not aware of an autocomplete feature, ...
2
votes
1answer
168 views

What's up with the ASxxx and the “CoCo Disk BASIC binary format”?

The ASxxxx assembler system is a multi-platform assembler that supports a lot of different CPUs, including Z80, 6800, 6502, 6809, etc. I'm intending to use it to build software for a variety of ...
2
votes
1answer
387 views

How did “RAM” cartridges for the C64 work?

Section 7.1.1.2 of the VICE manual mentions that cartridge slot 1 (of the four slots 0, 1, Main and I/O) in the emulator is special in that it's designed to support "mostly RAM-based cartridges" (of ...
11
votes
2answers
284 views

Reading old QIC-80 tape using Linux with ftape

I have an old Colorado 250MB tape drive, which connects to the PC's floppy controller, that I'd like to use to read a QIC-80 cartridge. I know that very old versions of the Linux kernel used to have ...
3
votes
2answers
380 views

Replacing cord for IBM model M keyboard

I bought a model m keyboard for use at work. The keyboard functions fine, but the cord is in bad shape. Functionally, the cord does not cause any shorts, but the plastic is very brittle and large ...
6
votes
0answers
105 views

Restoring a self-inking printer cartridge

I've seen people ask about restoring printer or typewriter ribbons, but my situation's a little different. I have a self-inking ribbon for a DECwriter Correspondent. It's easy to open up the casing, ...
3
votes
1answer
265 views

Was UCLA's 1948 Mechanical Computer programmable, or merely a calculator?

We define programmable machines as those that can do: sequence selection, and iteration ie the Turing Model of Computing. Here we see the UCLA's 1948 Mechanical Computer performing a calculation. ...
2
votes
1answer
321 views

Is the 3000T's case made by Commodore, or was it stock from elsewhere?

Is the 3000T's case made by Commodore, or was it stock from elsewhere? I need a side panel for one.
5
votes
1answer
217 views

Why does my Amgia 3000 show no Fast RAM even though the ZIP sockets are populated?

I am trying to get an Amiga 3000T up and running, all seems good but there's no Fast RAM. All Zips ard populated. Is there any (easy) way to test the ZIPs? Also, could something like a bad cap kill ...
3
votes
0answers
209 views

What was this music program I played with around the late 90s?

It ran on windows 95 or 98 I believe. It allowed you to make music by placing colored blocks in various rows. I think it was associated with mtv, but I'm not sure (I had never actually heard of MTV at ...
3
votes
0answers
101 views

CF with Workbench not loading in WinUAE but works on real A1200

I have a CF HDD with installed WB3.1, which works as expected on real A1200. Yesterday I wanted to copy over the latest ACA1221 soft, took the CF out, connected to PC just as normal. The WinUAE is set ...
5
votes
2answers
396 views

How do I adjust the OS print output to different screen dimensions on VIC-20?

The graphics chip of the VIC-20 has a setting for the number of columns and the number of rows to display. So, instead of the default values of 22 columns and 23 rows, for example, it is possible to ...
12
votes
4answers
697 views

How do you program Babbage's Difference Engine?

We know that Charles Babbage wrote a book of log tables: In doing this, Babbage was inspired to create Log Tables mechanically, leading to his design of the Difference Engine. The Difference Engine ...
13
votes
3answers
3k views

Why was Logo created?

The Logo programming language was created by researchers at MIT's AI Lab. Its post-1980s use has been predominately in the educational field, but is this what the language was originally designed for? ...
9
votes
2answers
253 views

Was it really possible for a PDP-11 to address more than 32K words memory without an MMU?

In an answer by user RichF, it is claimed that the previous-address-space moves were able to access 'all of memory' without memory management being enabled. The instructions MFPI (move from previous ...
11
votes
1answer
442 views

Under what circumstances would RAM locations 0 and 1 be written and/or read on the C64?

To be clear, I'm talking about the actual memory cells at addresses $0000 and $0001 in the DRAM chips. Devices can of course initiate read or write requests to these address on the address/data buses ...
3
votes
1answer
138 views

Did the IBM Game Control Adapter have I/O port aliases?

I was taking a look at the logic diagram in the manual for the original IBM game port adapter card: In the upper-left corner of the schematic, there is the circuitry responsible for decoding the I/O ...
6
votes
1answer
156 views

Was AppleTalk 422, 423, or something else entirely?

The Zilog SCC in the early Macs could operate in either 232 or 422 mode. AppleTalk used the later. 422 and 423 differed primarily in that the former used separate return lines for each data line, ...
6
votes
1answer
375 views

Could the Commodore 64 have used the 6522 VIA instead of the 6526 CIA?

The VIC-20 used a 6522 VIA chip with a couple of 8-bit PIO ports, a couple of timers and a (buggy) shift register. (The bug in the shift register could be worked around with external hardware or in ...
5
votes
1answer
166 views

How did this coordinate capture peripheral work? [duplicate]

From an 80s Royal Air Force recruitment video, a peripheral is shown and it is used to capture coordinates off a map, onto a computer, for the flight plan to be written on a casette, for loading on ...
19
votes
2answers
2k views

What causes the traces to wrinkle like this and should I be worried

I have a Macintosh SE in my collection and I noticed these odd looking traces on the mainboard. Not quite sure what to think of it
6
votes
2answers
312 views

Is it safe for C64 cartridges to respond to read and/or write requests on “unmapped” addresses?

According to the C64 wiki, asserting G̅A̅M̅E̅ on the cartridge port (and not asserting E̅X̅R̅O̅M̅) of the C64 leaves three blocks of the C64 address space "unmapped": 28 KB @ $1000 (otherwise RAM), 8 ...
14
votes
12answers
4k views

Late 1970s and 6502 chip facilities for operating systems

I'm quite unfamiliar with how operating systems used to be written but its clear to me that operating systems were clearly written for these systems. I'm particularly interested in how operating ...
3
votes
0answers
222 views

What's the first use of the term, “1977 Trinity”?

The term "1977 trinity" has been used, here on Retrocomputing SE and elsewhere, to refer to a set of three computers that started shipping in mid- to late-1977: the Apple II, the TRS-80 Model I and ...
0
votes
2answers
162 views

How do I round up on a TI-84+ [closed]

I'm using a TI-84+ and am trying to setup an equation that requires rounding up I know how to round and round down with the TI-84 but I can't seem to figure out how to round up Edit: the 'round down'...
2
votes
1answer
100 views

What are the screen editor commands for MIT LOGO for the Apple II?

I'm playing with MIT LOGO for the Apple II (1981). When I type TO GREET :NAME and hit ENTER it drops me into the "MIT LOGO screen editor." What are the commands I can use here to edit, save, etc.?
5
votes
3answers
1k views

What was the earliest microcomputer Logo language implementation?

Wikipedia has a long list of Logo implementations, but I'd like to know what the earliest implementation is on a microcomputer, or, more likely, what are the earliest ones if there isn't one with ...
11
votes
4answers
2k views

Amiga 500 OCS/ECS vs Mega Drive VDP

Superficially the Amiga 500 and Mega Drive are similar. Both run a Motorola 68000 CPU at similar clocks and both have dedicated hardware for sprite and other graphics operations. Comparing the arcade ...
9
votes
1answer
234 views

What was the purpose of the Apple /// interlace mode?

I know that a video interlace mode was available on the Apple /// prototype and eventually on the Apple ///+, but I haven't seen anything that says what it was for. Did it provide a higher resolution ...
4
votes
5answers
1k views

Real mode flat model

I am interested in old Intel processors. I'll try to be as concise as possible. I have been studying both Jeff Duntemann's Assembly Language Step-by-Step - Chapter 4 and Modes of Memory Addressing on ...
20
votes
3answers
2k views

Bit one of the Intel 8080's Flags register

Did bit one of the Intel 8080's Flags register, the bit between the carry and parity flags, get set to one on startup? If so what was the reason for this, and was this inherited from the 8008 Flags ...
1
vote
1answer
256 views

Can you help me identify this AMD 386-DX40 motherboard?

I'd like to find some documentation for this mainboard I just picked up for my very first retro computer, but I don't see any brand or model markings whatsoever. Does anyone have any tips? P. S. I ...
24
votes
3answers
3k views

What are uses of the byte after BRK instruction on 6502?

The BRK instruction on the MOS 6502 seems to be one of the more ill-documented features of the processor. The 1976 preliminary data sheet from MOS indicates that it's a 1-byte instruction using the "...
2
votes
2answers
291 views

How much PSU power do I need for an AMD 386DX-40 computer?

Just picked up my first retro PC the other day. Unfortunately, it's lacking a PSU so I need to find one. What kind of a PSU (in terms of wattage) do I need to comfortably run an AMD 386DX-40 system? ...
17
votes
4answers
760 views

Did Apple really advise customers to lift up and then drop their computers?

This led to the infamous technical note where Apple recommended users facing problems with the Apple III to lift the computer two inches and then drop it, as this would set the circuits back in place.[...
9
votes
1answer
2k views

What was the first LISP compiler?

LISP is generally considered an interpreted language, but compilers have been made for it. What was the first compiler? To be clear, this is about compilers that compile LISP code stored for ...
9
votes
2answers
412 views

How do you send code to a Commodore disk drive and run it?

Commodore disk drives such as the 1541 used with the Commodore 64 and similar computers, and the earlier 8050 used with the PET series, had their own 6502 CPU and 2 kB or so of RAM used to run the ...
5
votes
1answer
85 views

What is the floppy disk port pinout for the NEC PC-8001mkII?

I have a NEC PC-8001mkII computer (sometimes incorrectly called a "PC-8001mk2") which has a built-in disk controller for PC-8000-series double-density 5.25" drives. (The English and Japanese Wikipedia ...

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