All Questions

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

ISA Extension cards using more than 64kB

Related to my previous question around VGA framebuffer being limited to 64kB I started to wonder if there was any extension cards (or similar) using more than 64kB of address space in linear fashion, ...
6
votes
3answers
1k views

Why VGA framebuffer was limited to 64kB window?

VGA framebuffer was fixed to 64kB at A0000h. Right after that there’s MDA/CGA framebuffer at B0000h. I am not sure, but I recall VGA did have to support CGA and its framebuffer, but was there any ...
5
votes
1answer
194 views

What was the reasons for DEC engineers to choose MMU page size in VAXen?

MMU page size in VAXen is just 512 bytes. Such a small size causes increased number of MMU page walks and leads to TLB thrashing more often. Current tendency is to have MMU pages as big as 2 Mbytes. ...
37
votes
1answer
6k views

Fixing obscure 8080 emulator bug?

I'm using the cpudiag.bin from http://www.emulator101.com/files/cpudiag.bin to test my emulator. I've already implemented the CP/M CALL function at 0x05, offset the program at 0x100 and fixed the ...
50
votes
6answers
10k views

How did old MS-DOS games utilize various graphic cards?

Nowadays each graphic card has some driver in operating system that translates some (typically) standard API such as OpenGL, so that programmers use some standardized API code to tell graphics cards ...
2
votes
2answers
225 views

How exactly do all control signals in 6502 work?

I'm trying to make a 6502 replica in Logisim. I want to know what exactly each control signal in 6502, how the clock cycles work and additionally I would like to see an example of these control ...
17
votes
3answers
6k views

Why was the Sega Genesis marketed as a 16-bit console?

The Sega Genesis / Mega Drive's main CPU, the Motorola 68000, was a 32-bit processor. Couldn't Sega have marketed the console as a 32-bit device? Or is there a technical distinction about how the ...
6
votes
4answers
810 views

Was the output of the C64 SID chip 8 bit sound?

Was the output of the C64 SID chip 8 bit sound? I know that SID is not sample based, but instead generate its sound using sine waves and white noise. So is it correct to say that the audio ...
0
votes
1answer
389 views

What was the first Linux distribution?

I desire to know what was the very first Linux-kernel based operating system, what we can call today a "distribution" even if the term wasn't used then. The Wiki article doesn't give a clear answer, ...
2
votes
2answers
474 views

When did various PONG systems overflow/crash due to points?

Edit: Given the many different versions of the game Pong, which version allowed you to accumulate the highest score before the game would crash, reset, or otherwise not just give you one more point? ...
16
votes
1answer
4k views

When did Linux kernel become libre software? [closed]

In this video, Richard Stallman claimed that Linus Torvalds created Linux kernel as a proprietary software and then liberated it ('liberated' is the term Stallman used). Assuming so, when was the ...
0
votes
3answers
699 views

Was Hurd kernel created as a modification of Linux kernel?

As I know, shortly after Linus Torvalds liberated the Linux kernel it was implemented in GNU operating system which is since then known as GNU/Linux or GNU+Linux. From the GNU article in Wikipedia I ...
13
votes
3answers
2k views

What LISP compilers and interpreters were available for 8-bit machines?

What LISP or LISP-like language compilers and interpreters were available for 8-bit microcomputers? Criteria for "8-bit" include that it should certainly run and execute non-trivial programs given no ...
3
votes
1answer
376 views

Z80N multiply compared to MC68000 [closed]

According to this answer (How did multiply instructions work in the various 68ks?) the MC68000 can take up to 70 clock cycles to multiply. The ZX Spectrum Next's FPGA based Z80N has a MUL DE ...
11
votes
1answer
6k views

Did the first version of Linux developed by Linus Torvalds have a GUI? [closed]

Does the first version of Linux developed by Linus Torvalds have a GUI (not necessarily Iconic but something simpler like Midnight Commander)?
4
votes
2answers
228 views

Where can I read the article from Personal Computer World, Nov 1978, which introduced the 8th Rugg/Feldman test program?

I'm trying to track down a copy of PCW from November 1978. I am looking for an article on benchmarking BASIC. They introduced an 8th program to the 7-program Rugg/Feldman test and I'd like to read the ...
3
votes
2answers
209 views

When and why would MacinTalk say “open-apple hold”?

I'm trying to confirm a vague recollection about the text-to-speech PlainTalk / MacinTalk software shipped with Macintosh computers. If my memory is right, this would have been around 1994, and based ...
3
votes
5answers
220 views

What use are the data direction registers in the MOS 6526 CIA?

As described in the MOS 6526 CIA data sheet (at the bottom of page 5) and this answer, the PA0-7 and PB0-7 pins: always act as inputs, even when the data direction register (DDR) is set to 1 ("output"...
20
votes
1answer
2k views

Why was it possible to cause an Apple //e to shut down with SHIFT and paddle button 2?

Looking at the MAME driver for the Apple //e, I noticed an interesting comment: NOTE: On real IIe and IIe enhanced h/w, pressing SHIFT and paddle button 2 will short out the power supply and cause ...
3
votes
1answer
190 views

Apple I and II video output to a contemporary TV set?

Is it possible to connect the unmodified video output from an Apple 1 and Apple II (with their non-standard/our-of-spec NTSC sync pulse levels and/or timings) to a (currently in-production and ...
9
votes
3answers
1k views

What is the best option to connect old computer to modern TV

I was exploring different options of connecting both my Atari ST and C64 to a modern TV. I opted for a composite signal passed through a cheap AV to VGA converter, and although the display works, ...
2
votes
1answer
118 views

can i build a colecovision ac adapter

Can I use multiple small AC adaptors to make a working Colecovision AC adaptor? For example, two 5V, one 12V and the ground. Colecovision AC adaptors are too expensive.
5
votes
1answer
295 views

Where are the pullups for the Commodore 64 keyboard matrix lines?

I'm looking at the schematic and the Service Manual for the Commodore 64. I can't seem to find a schematic for the keyboard itself. It seems clear that the control port 1 joystick has normally open ...
4
votes
1answer
170 views

Atari 1040ST AV video output - blurred and jagged vertical edges

I have an AV cable that connects Atari 1040STE with a AV to VGA converter. For some reason the vertical edges are not sharp, rather jagged or pixelated. I red that old atari would have an issue with ...
9
votes
1answer
312 views

How did the Zip Chip and RocketChip accelerators work for the Apple II?

Though there is already a similar question on the site, this one is more specific to these chips and their technical implementation. There were two accelerators for the Apple II series that were drop-...
6
votes
1answer
199 views

Monitor for an SGI Octane?

I just found myself being the sudden and proud owner of two wonderful Silicon Graphics machines, an Octane and an Octane 2, both in quite good condition (in particular with very few scratches to the ...
15
votes
1answer
378 views

In the original Z80 layout, where are the “traps” located? And what are their effects?

According to Zilog Oral History, Zilog only had a tight schedule to design the Z80. Facing the potential competition, Federico Faggin and Masatoshi Shima were worrying about Japanese semiconductor ...
16
votes
2answers
2k views

Looking for an old image of designing a CPU with plan laid out / being edited on a literal floor

There is an image that I remember seeing, but that I have never been able to find. It shows 2-3 people on their hands and knees, crawling around a blueprint of a chip that had been rolled out over the ...
2
votes
0answers
144 views

Would anyone have made a mechanical, or electronic camera for their computer or robot? [duplicate]

Would anyone have made a mechanical, or electronic camera for their computer or robot ? Parameters Of The Question As a home-project [ Although, any example of a mechanical-tv-camera or mechanical-...
5
votes
0answers
235 views

Does the Commodore 64 power switch have a history of failing?

My original (1983?) Commodore 64 (brown breadbox with grey function keys) has trouble powering on. Specifically, when I flip the power switch the power LED will glow dimly and the machine fails to ...
47
votes
3answers
7k views

Strange math syntax in old basic listing

I'm browsing through an old book "Basic Computer Simulation" from 1983. It contains a line of BASIC code that reads: LET Z1 = M * D1 * (PQ / A) [ 3 I understand all of the code except the "[ 3" I ...
21
votes
2answers
5k views

What is a subpixel in Super Mario Bros, and how does it relate to wall clipping?

What are "subpixels" in Super Mario Bros on the NES? How does it relate to wall clipping? At 4:42 in the following video, the notion is mentioned in the context of how it relates to "wall clipping": ...
6
votes
2answers
1k views

What is this side-scrolling fighting game for the Amiga?

I remember playing this game on an Amiga. I have no idea what it was called.
29
votes
9answers
9k views

How did early x86 BIOS programmers manage to program full blown TUIs given very few bytes of ROM/EPROM?

I've always wondered how so much functionality and relative luxuries(CMOS Configuration Utilities. See: https://geekprank.com/bios/ for an example) included with most popular x86 BIOSes could be ...
31
votes
5answers
4k views

Why does the 6502 have the BIT instruction?

The 6502 has a bit instruction which copies two of the bits into the N and V flags, pretends to and the byte with the accumulator, but discards the result and only affects Z. I'm having a hard time ...
20
votes
3answers
2k views

When and what was the first 3D acceleration device ever released?

Plain and simple, we know that consumer level 3D acceleration devices roughly appeared in the middle of the 90s, with brands like Matrox, 3DFX, Nvidia and so on. However, such technology for sure ...
36
votes
4answers
4k views

Why are C64 games inconsistent with which joystick port they use?

The Commodore 64 has two DB-9 joystick ports. If I'm the only person that ever plays games on it, you would assume that you could just leave a joystick plugged into Port 1 and be done with it. However,...
8
votes
2answers
285 views

Texas Instruments SN502

My father is an engineer that worked at TI directly under Jack Kilby in the early 60’s. This chip was given to him by Kilby as a “thank you” for all his hard work. We also have the accompanying build ...
9
votes
4answers
1k views

Compaq Portable vs IBM 5155 Portable PC

In 1983, Compaq introduced its first product, a portable computer weighing 28 pounds; 128-640K RAM, two 5.25" floppy drives, 9" monochrome CRT for $3590. It was extremely successful in the market, and ...
13
votes
2answers
408 views

What is known about the internal workings of the Z80?

There is a wonderful project called Visual6502, and I've used it from time to time to figure things out, like exactly the difference between rti and rts. It is good to see which control lines were ...
23
votes
4answers
4k views

Can my floppy disk still work without a shutter spring?

One of my floppy disks' shutter spring got lost. Now the shutter can't slide normally. Can I still use the floppy disk?
7
votes
2answers
409 views

What was the Macintosh's BOM cost?

Andy Hertzfeld revealed that the CPU for the original $2495 Macintosh cost just $9.00. How much did the rest of the computer cost? Was the markup really greater than Pepsi's markup on sugar? How much ...
6
votes
4answers
520 views

Set screen resolution in DOS-only PC

I replaced a failed CRT display with a LCD panel with a VGA controller board. There is no problem with the display when the PC boots up. However, if I switch the display off then I get an 'Out of ...
12
votes
2answers
2k views

What is the purpose of the yellow wired panels on the IBM 360 Model 20?

I just finished reading a story about an IBM 360 Model 20 rescue, and some of the pictures caught my eye. Specifically this one: Searching online, led me to several more pictures, all with ...
47
votes
5answers
15k views

What did the 'turbo' button actually do?

I remember the computer I played Commander Keen on as a child had a turbo button that I was forbidden to touch, what did this button actually do?
14
votes
4answers
3k views

Why do the i8080 I/O instructions take a byte-sized operand to determine the port?

I thought the i8080 had 8 16-bit IN ports and 8 16-bit OUT ports. Doesn't that mean the instructions IN d8 ; only index 0-7? OUT d8 can only take 8 possible values? What would it be indexing ...
3
votes
3answers
303 views

Creative uses for serial port? [closed]

I know it's still used for many industrial microcontrollers but that's not what I am asking; I also know that it's quite slow. It's just that I hate seeing an unused port on my desktop pc, while all ...
6
votes
1answer
170 views

Why does the Apple IIgs FPI chip buffer the A14 address signal to the ROM?

In the Apple IIgs computer, the address and data buses of the 65C816 CPU connect directly to the onboard ROM, except for A14, which, according to the schematic, is routed through the FPI ASIC. There's ...
9
votes
1answer
159 views

Patch BBC Master ROM using Sideways RAM?

I have a BBC Master 128 with the standard ROM installed. This includes ADFS v1.50 in slot "D". I want to replace this ADFS in ROM with a patched version, loaded from disk, into Sideways RAM. It is a ...
3
votes
0answers
176 views

Early 1982 PCW article about pseudo random dungeon mapping

I am looking for an article from an issue of Personal Computer World (PCW) from 19821 which related to generating mazes/dungeons using pseudo random seeds, what I think are (now) called procedural ...

15 30 50 per page