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2
votes
1answer
32 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 ...
4
votes
3answers
424 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 was the language was originally designed for? ...
4
votes
1answer
88 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 ...
7
votes
2answers
313 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 ...
2
votes
1answer
84 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 ...
5
votes
1answer
110 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, ...
4
votes
1answer
170 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
123 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 ...
13
votes
1answer
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
5
votes
1answer
138 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 ...
13
votes
10answers
3k views

Late 1970's 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
178 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
140 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'...
1
vote
1answer
77 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
985 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
1k 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
206 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 ...
19
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
218 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 ...
23
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
253 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? ...
16
votes
4answers
644 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
352 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
74 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 ...
2
votes
2answers
221 views

ZX Spectrum +2 not saving

I have a ZX Spectrum+2 with the built in tape deck. I can load tapes no problem, when I try to save, I get the border lines. When I try to reload the program I get nothing Any help would be greatly ...
10
votes
1answer
341 views

When was “Cable Select” introduced for IDE devices?

Conventional IDE (or parallel ATA) controllers support two devices per controller; these are designated Master and Slave, and need to be configured as such with jumpers on the devices. In later years,...
38
votes
4answers
7k views

When did computers stop checking memory on boot?

I remember my old 8088 used to do this (640K OK) but can't remember seeing anything like this since. Does this still happen and it's just not visible? If not, when did it stop, and why? (Imagining ...
19
votes
1answer
1k views

Why does PAUSE key have a long make code and no break code?

On IBM keyboards, scan code sets 1 and 2 have a long make code and lack a break code for the Pause/Break key. Moreover, when Ctrl is pressed, the make code is different, although break code still ...
2
votes
0answers
121 views

Can a bootable Win9x HDD be made interchangeable between PCs?

Normally, Windows 9x must be installed on each PC individually so that it can be loaded/configured with the appropriate set of drivers. I'm wondering if there is any way to make a boot HDD that can be ...
4
votes
3answers
174 views

Are there standard DIN pinouts for cassette and video ports on early Japanese 8-bit computers?

I have several different Japanese 8-bit computers, and they use similar DIN connectors for video and cassette I/O: Composite video: 180° 5-pin DIN: Fujitsu FM-7, NEC PC-8001mkII Color TTL (digital) ...
8
votes
3answers
193 views

Set keyboard layout in Amiga Workbench 3.1

I did a fresh install of the Cloanto amiga-os-310-install.adf disk to a hard drive, and then I wanted to change the keyboard layout to Swedish. I tried SYS:System/SetMap s but then I've learned that ...
5
votes
2answers
169 views

How do I use NEC PC-6001 .p6 or .cas files?

The Neo Kobe - NEC PC-6001 "software capsule" on Internet Archive includes a 126 MB ZIP file, Neo Kobe - NEC PC-6001 (2016-02-25).zip, containing a subdirectory 1-Screen Programs (Kaw)/. This contains ...
11
votes
1answer
660 views

Does the Commodore CDTV-CR contain a 65C02 for some reason?

Browsing around the FS-UAE source code I discovered a 65(S)C02 emulation core, which appears to not be referenced anywhere outside of some CDTV-CR related source file. Apparently, a CDTV is ...
30
votes
3answers
6k views

Why does 8 bit truecolor use only 2 bits for blue?

From Wikipedia: The other form is where the 8 bits directly describe red, green, and blue values, typically with three bits for red, three bits for green and two bits for blue. This second form is ...
0
votes
0answers
84 views

What cable do I need to connect my old commodore64 with a tv (as monitor) [duplicate]

I want to use an old commodore64. In the 80s we connected a small tv, as a monitor, but the cable for that connection is missing. What kind of cable connection do I need?
3
votes
1answer
238 views

TRS-80 Model 100 is frozen, even after multiple resets

I replaced all leaking capacitors about 4 months ago. I cleaned it out the board tediously. Every-time I switch on my old computer it is stuck on the menu screen. The machine does not respond to the ...
3
votes
4answers
480 views

How slow is Z80 compared to Arduino Uno?

How slow is z80 compared to Arduino Uno when they read an output pin if the Z80 is 2.5Mhz?? I/O cycle and cpu herz and is there anything else to consider?
16
votes
1answer
2k views

Do we know the problems the University of Manchester's Transistor Computer was intended to solve?

We can see that the University of Manchester built a transistor computer in 1952. This appears to have been the first transistor computer. We can see that the design was used in the Metrovick 950. ...
8
votes
3answers
455 views

Why did 1970s front panels prefer momentary toggle switches to push buttons?

This question is about computers with front panels that use only toggle switches for input of binary data (such as address and data values), as opposed to keypads for numerical input or other methods. ...
51
votes
5answers
14k views

Why do old games use flashing as means of showing damage?

When you play old games, especially platformers, a common "special effect" is rapid blinking of your character when they are hit. Also, enemies often blinked before dying. Not all games did this, but ...
32
votes
3answers
3k views

Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?

In short, 3 µm looks like it was the "standard" process size at the time, and it was available to Commodore before the chips were designed. Therefore it looks like using the larger 5 to 7 µm process ...
13
votes
3answers
1k views

What are the electrical characteristics of a PC gameport?

I'm considering building some custom gizmos to connect to the gameport on my retro-hobby PC (SNES controller adapter, macro/turbo box, etc.) but I haven't been able to find much information on details ...
12
votes
3answers
782 views

How did the Altair 8800 front panel load the program counter?

My understanding is that when you toggle in an address on the Altair 8800 front panel switches and then press the EXAMINE switch, it loads the program counter with that address, or at any rate does ...
9
votes
2answers
1k views

Small RAM 4 KB on the early Apple II?

Most of the reference material for the Apple II that I have seen refers to the 4116 RAM chip which held 16x1 kbit. This provided 16, 32 or 48 KB in banks of 8 chips. The Apple II motherboard layout ...
5
votes
2answers
296 views

Build a hardware clone or emulator of Apple II?

These days we are constantly seeing low-cost boards that have huge power (raspberry pi, various arduino-like microcontrollers.) I am hoping I could make, or get, a clone or emulation of an Apple II ...
4
votes
1answer
226 views

Discharging an AT power supply for maintenance

The power supply for one of my computers needs a new fan. How do I discharge the power-supply capacitors to make it safe to open up? With an ATX power supply, it's just a matter of unplugging it, ...
2
votes
2answers
317 views

emulator library that allows to partially emulate old games [closed]

EDIT: previously I added a lot of examples to this questions. I removed the examples, because the question was voted to be "too broad", so I put more emphasis on the question again. Question: Is ...
6
votes
7answers
1k views

What ways are there to “PEEK” memory sections in (different) BASIC(s)

Question Was there any BASIC or extension or toolbox for BASIC allowing to PEEK multiple bytes from memory in one instruction - beside the often used DPEEK (or alike) to read a word. I'm asking ...

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