All Questions

Filter by
Sorted by
Tagged with
2
votes
2answers
41 views

Is it possible to swap the Apple //c's monochrome CRT tube for a color one?

I just love the Apple //c's snow white industrial design, especially when paired with its monitor //c. It is a classic design that doesn't show its age. I've even recently seen them setup in homes ...
1
vote
1answer
79 views

When first CMOS versions of Z80 became available and were they ever used in (non-portable) home computers?

When Z80 first became available on the market in 1976 it was made using NMOS technology. It is the version that is likely to be most familiar to people interested in retro-computers. For example, to ...
11
votes
6answers
1k views

What is the reason the 8051 was not used in 8bit computers?

The 8051 is a Harvard-based microcontroller, but it allows us to connect external memory and simulate von Neumann's architecture. What is the main reason it was not used widely in 80's home computers? ...
7
votes
2answers
681 views

When was DEFUN added to Lisp?

I don't see DEFUN in a ~1966 copy of PDP-6 LISP. I do see it in a 1972 Maclisp. AI memo 116A from 1967 doesn't have DEFUN. (It does have MACRO.)
9
votes
3answers
1k views

How to use rounding with 6809 multiplication

The MC6809 is unusual for an 8-bit processor of its era in having a hardware multiply instruction. MUL multiples the 8-bit unsigned integer in the A register with the 8-bit unsigned integer in the B ...
13
votes
2answers
685 views

Does the Z80 allow interrupts after processing and ignoring a 0xdd prefix?

I read here that if the Z80 encounters e.g. multiple 0xdd prefixes in sequence, for each 0xxdd except the last it acts almost like a NOP, but does not allow interrupts to occur immediately after "...
9
votes
1answer
145 views

How can slot 1 of the Apple ][ replace the keyboard?

Nick Westgate posted a comment a few years back on a question about how slot 7 was unique stating that "Slot 1 on the //e is also unique - it can be used to replace the keyboard". What was it about ...
3
votes
1answer
180 views

Origin of “640K RAM is enough” quote

Yesterday I was digging through a rather long directory path to watch an episode of Fist of the North Star (on Windows 8.1) when I was hit with an error message: The path name is too long I looked ...
5
votes
1answer
190 views

Why did the Sinclair QL keyboard lack a Delete key?

Reference: picture at https://en.wikipedia.org/wiki/Sinclair_QL It seems like an odd key to omit, given how frequently used it is and given that both the Spectrum + and 128 have one, which acts like ...
10
votes
1answer
722 views

Difference between Intel 8087 and 8089 opcodes

The 8087 floating-point coprocessor presumably used different ESC codes to the 8089 input/output coprocessor, since then they would be able to listen over the bus for their own ESC instructions. The ...
3
votes
2answers
108 views

Are there Commodore BASIC 7.0 music demos?

Commodore BASIC 7.0 that came with the Commodore 128 provided commands for playing music notes and setting different instruments. The play function even had a feature that played a note in the ...
28
votes
4answers
7k views

Apocryphal (?) tale of hard drive platter propelled through a wall?

In the mid-1990s while a student at a US university during a computer science lecture, my professor (not a TA or grad student) told us a story of "witnessing" a large, then old-fashioned metal hard ...
0
votes
1answer
71 views

How is the LCDC (LCD Control) register manipulated on the Gameboy?

I don't see it listed anywhere in the 0000-ffff address space. Is it controled by the CPU? Or something else entirely?
16
votes
5answers
4k views

Why did the Z80 with 4-bit ALU out-perform the fully 8-bit Intel 8080?

Looking at the development and architecture of the Z80, it appears to be a scaled-down, cost-reduced (in terms of total system cost), clone of the Intel 8080. It only used a 4-bit ALU. I assume this ...
1
vote
1answer
71 views

Can I connect a Sega Megadrive or Genesis to an Amstrad Cpc monitor?

I'd like to buy an old Sega Megadrive, aka Genesis outside the UK. However I don't have a TV or computer monitor to view the graphics on. I do however have an Amstrad Ctm644, which is a 15Khz CRT ...
-1
votes
0answers
60 views

Why must function declarations be followed by brackets when no parameters are passed? [migrated]

I understand that in many programming languages, function routines have what I can generally name a "default array", usually symbolized with parenthesis and if it is not empty, it is utilized in ...
2
votes
1answer
50 views

What was the last of the Thinkpad X series with replaceable RAM? [closed]

I know my x230 has replaceable RAM. I know the x395 lists its ram as being soldered. What is the last of the X series lineup with user-serviceable RAM?
7
votes
2answers
292 views

How to pass data pointer to subroutine to use with Absolute,Y addressing?

I may be going about this the wrong way, so sorry if it is wrong, I'm coming to 6502 after 32 years (when I was 8 years old !) I want to pass a pointer to some data, either data1 or data2 to a sub ...
3
votes
1answer
77 views

Microware OS-9 assembler warning with no message

My 6809 assembly language program for the coco3 is causing the assembler to issue a warning with no message. How can I find out why the warning is being issued? From the assembly listing, showing ...
3
votes
3answers
614 views

What were some of the earliest common webservers and how did they work? [closed]

And by Web server I mean actually web server (not BBS), meaning it had to run on the actual IP internet and be browsed with a dedicated browser program. So what kind of tools were used in the late 80s/...
1
vote
0answers
40 views

Thinkpad 380E keeps shutting down randomly [closed]

Recently, I got a 380E from ebay. Seller says that it has boot error and not working, but the error was typical 161/163. I've replaced nee BIOS battery, and error was gone. After that, I formatted ...
3
votes
1answer
62 views

Why does MS-DOS 5.0 EDIT hang on my XT-class machine with a German 102-key keyboard?

Most times whene I call EDIT on my XT-class machine with MS-DOS 5.0 installed on the hard disk, the menus of EDIT appear, but the window that should contain the file contents stays blank and the ...
3
votes
2answers
187 views

What's the Motorola microprocessor with two sets of registers to avoid costly context switch?

I remember reading somewhere (maybe on Hacker News or Lobsters) that Motorola made a microprocessor some decades ago with two sets of registers. This means when handling an interrupt, it does not need ...
0
votes
0answers
80 views

Is there any way by which I can quickly run 16-bit programs without any visuals? [closed]

I know that DOSBox can be used to run 16-bit executables and my problem can be solved by setting SDL_VIDEODRIVER=DUMMY But the problem with using the above method is that it is time consuming as ...
18
votes
6answers
1k views

Sound driver for DOS or Windows 3.x that used the PC speaker?

Long ago in a galaxy far far away, back in the early 90's, I worked for a crappy clone company as a phone technician. At the time, 386SX/25's were common for in-house technical support / customer ...
2
votes
1answer
84 views

For TRS-80 Color Computer joystick buttons, is it correct to check the first or second bit of the value at PEEK(65280)?

The Color BASIC/Extended Color BASIC “Getting Started” manuals say that to find out if a joystick button is pressed, to PEEK in location 65280. The value 255 means neither button is pressed; the ...
26
votes
15answers
8k views

Was it possible to listen to music and work on old PCs? When was it possible to for the first time?

I was wondering the other day, would it be possible to listen to a midi on a C64 while writing a program or something. I mean it did have a sound chip that would technically just get some new buffers ...
2
votes
2answers
165 views

Could Apple II cards be used on any 6502 platform?

Looking over the Apple II expansion card pinout, it seems it's largely just the pins of the 6502 plus some +12V supplies and such. Generally speaking, though, is there any reason any other 6502 ...
7
votes
2answers
1k views

Did general purpose I/O controller chips come with fewer than 40 pins?

I'm aware that 40-pins was a high-water mark for dual-inline package chips for a significant time; many CPUs of the early 1980s (8086, Z80, 6800, 6502, etc) used 40-pin packages, but no larger. ...
10
votes
3answers
343 views

Shape of Cray-1

One way the fast speed of the Cray-1's CPU was achieved was by keeping the wire lengths short. How did the C-shape of the Cray-1 help here? Were the speed-dependent portions on the inside edge where ...
3
votes
1answer
274 views

What was the purpose of exotic modes and sectors for CD-ROM?

(I ask the question again, one suggested SuperUser, but I was right, it has been closed instantly.) There are well-known sectors and modes for CD-ROM medias: CD-DA: for storing music in a digital ...
4
votes
1answer
182 views

YMODEM specification problem?

I'm looking over the documents for YMODEM found here. Scroll down to page 8, the section on 1-k blocks. Note that the protocol can switch between 1024 and 128 bytes by sending an STX or SOH. Now ...
25
votes
4answers
6k views

Unix Haters Handbook - guaranteeing synchronous, atomic operations

I've come across Filesystems with versioning and have been reading through the Unix Haters Handbook, linked there. I came across page 85: On the other hand, techniques for guaranteeing synchronous, ...
1
vote
0answers
67 views

When and with which system or software was IBM's system of tape headers (VOLx, HDRx, …) introduced?

Background: IBM compatible tape structure (*1) consists of a series of label blocks describing the volume and each file (Data Set). Essential the structure looks like this: VOL1..9 Volume header ...
0
votes
2answers
154 views

Handheld Systems Archives CD-ROM

Does anybody know if this is available anywhere? The domain seems to be gone. Clarification: this magazine was published in the 1990s. According to worldcat.org a couple of US uni's have copies, but ...
7
votes
0answers
157 views

What are some early network file systems?

I know it's always hard to define an exact first, so I'll just ask about early network file systems. To be more specific, I'm wondering about file systems that transparently present directories and ...
3
votes
1answer
178 views

Checking Old Tapes

How do I check old ZX spectrum cassettes work - the tapes are after all quite old? I am fairly computer savvy (my life is a continual strand from that Speccy to this here Thinkpad - and many stations ...
37
votes
5answers
10k views

How did Atari lose money on home computers?

The answer recently posted to Did Atari make more money from arcade games or consoles? quotes a New York Times article from 1982 https://www.nytimes.com/1982/12/19/business/the-game-turns-serious-at-...
10
votes
4answers
1k views

Is it a Directory, a List, or a Catalogue?

There are three common CLI commands on microcomputers that all mean the same thing: "Show me the contents of a volume, disk, or sub-directory". I will mention that the noun "Catalogue", and the ...
10
votes
2answers
687 views

Zilog Z80 estimated time discrepancy

I am writing a basic Zilog Z80 assembly language interpreter and something I noticed as I went through the 8 bit load commands is that the estimated times for LD (IX+d), n and LD (IY+d), n are ...
14
votes
11answers
6k views

How can a Z80 assembly program find out its own memory address?

I'm wondering how to write a program in Z80 assembler that discovers its own memory location. I thought that maybe I could somehow load the program counter PC into, for example, BC. Is there a way ...
1
vote
3answers
188 views

Were there ever any thermal printers that simply “muscled” plain paper? [closed]

Theoretically, one could probably build a thermal printer (maybe with a laser) that simply burns the paper black where you want it black. Conceivably without embrittling the paper too deeply or ...
5
votes
0answers
189 views

Fixing an ailing Amiga 500

My old Amiga 500 has been living in its box for the past 20 years and does not function as it should. When turned on initially it seems to work fine, loads the Workbench disk and allows me to open/...
4
votes
1answer
709 views

6502 - AND instruction updates flags differently than other logic operations

Why AND instruction updates flags in the fetch step? Others logic instructions like ORA and EOR update flags in the same step that they update accumulator, in the decode step. Is it a bug of ...
9
votes
2answers
265 views

Can a 1,44MB or 720K PC floppy drive be made to work with an Apple II family?

I am restoring a couple of Apple II machines. I would like to add an external 3.5" floppy drive, but they are prohibitively expensive. I have tons of older PC floppy drives and I wonder if they could ...
2
votes
2answers
289 views

Why did extracodes fall out of favour?

Once you have an operating system that provides services callable from programs, you need to provide a way for programs to request those services. These days the general approach only requires a ...
2
votes
0answers
84 views

Commodore tape drive performance specs

Over the years during which Commodore sold tape drives, there have been a few different versions of the drive with different analog electronics. I'm interested in experimenting with "turbo" tape ...
8
votes
1answer
263 views

Did Atari make more money from arcade games or consoles?

Atari was originally an arcade game company, starting at the beginning of the seventies with Computer Space and Pong. In 1977, they entered the console business with the VCS a.k.a. 2600; in 1979, they ...
0
votes
2answers
107 views

In the Amstrad CPC's Mode 0, what was the design rationale for interleaving the pixel bits?

The following tables are modified and corrected from Painting pixels: Introduction to video memory. m-bit: memory bit p-bit: pixel bit Mode 2 - 640x200 (half width pixels), 2 colours m-bit | 7 | 6 |...
7
votes
4answers
500 views

How do you play “The Sentinel”?

Many, many years ago, we had a game for the Commodore 64 called "The Sentinel". I remember reading the instructions and being utterly baffled as to how you actually play the damned thing! Hopefully ...

15 30 50 per page
1 2 3 4 5 59