All Questions

10
votes
1answer
185 views

Could suitably-written Apple-I software force bytes into the display shift register, and do modern recreations emulate that?

The original Apple I didn't use RAM to hold the contents of the display, but instead used a group of six 1024-bit shift registers to hold the display contents and a seventh 1024-bit shift register to ...
2
votes
3answers
314 views

What do the numbers on the punch cards mean?

Does anyone know what is the meaning of the numbers in punch cards? I need an example of any language, it's important for me to understand which information could be manipulated.
1
vote
1answer
431 views

Wider tower cases

Desktop computers have been in tower cases for a long time; in some cases since the eighties, per When did the tower form factor appear and when did it become popular? The form of tower cases has ...
26
votes
3answers
5k views

Why separate cursor keys?

The original IBM PC keyboard didn't have separate cursor keys; the numeric keypad doubled as such. It wasn't long, however, until a new keyboard was introduced that did have separate cursor keys (so ...
9
votes
3answers
729 views

IBM PC expansion card latency

In the IBM PC and early successors and compatibles, it was commonplace for most of the computer's memory to be on cards in general expansion slots. (e.g. the original IBM PC could take 64K on the ...
4
votes
2answers
167 views

How to exactly sync to the raster line for a vertical raster split?

Motivated by Wilson's question Can a Commodore 64 use two screenmodes on one scanline? I tried to implement a simple example that polls the beginning of a rasterline and then switches the screen mode ...
2
votes
1answer
93 views

What is the 26-pin D-sub (DA-26) connector used for on the Media Vision Pro AudioSpectrum 16 Patch Panel?

My dad has this audio interface from the 90s called the Media Vision Pro AudioSpectrum 16 Patch Panel, but unfortunately doesn't have the manual. From my research, it appears that this panel was used ...
0
votes
1answer
123 views

How viable is a universal PC parallel/serial connected CP/M disk controller/drive?

I had an idea and wanted to hear if there are any major technical obstacles. Imagine any vintage computer with either a serial port or a parallel port. The vintage computer is connected via that ...
8
votes
1answer
193 views

Were any PDP-11 systems with Corita Kent side-panels actually sold?

Somewhere around 1980, I heard about PDP-11 systems that had side-panels designed by Corita Kent (a nun and pop artist, who amongst other things designed a stamp for the US post office, and gas ...
4
votes
4answers
288 views

How much did a serial terminal cost?

For many years in the mid-to-late twentieth century, user-facing computing consisted primarily of serial terminals attached to mainframe and minicomputers. In the eighties and even as late as the ...
4
votes
1answer
128 views

Why did Extended BASIC on the TI-99/4A only allow 28 of the 32 sprites?

The Video Display Processor (VDP) of the TI-99/4A was capable of displaying 32 hardware sprites. These sprites were unusable with the default, built-in BASIC that TI provided. However, an enhanced ...
2
votes
3answers
450 views

Daisy wheel graphics using the period?

Although it would have absolutely beaten the hardware to death, did anyone ever try to write a graphics driver for daisy wheel printers that would use the period symbol to painstakingly construct a ...
1
vote
1answer
144 views

Could a 6502 use different speeds of RAM in a single machine?

I'm not sure I've entirely formed the idea in my head, but I'll ask anyway... One of the things I learned here in RO is that the BBC gained speed by using faster RAM, thereby avoiding cycle stealing ...
14
votes
1answer
924 views

In CP/M, how does control-Z (hex 1a decimal 26) not interfere with ordinary file storage?

Consider this - I have made a file called test.bin on a Windows machine. It is exactly 256 bytes long, and contains nothing more than 00 to ff in each byte. What would happen if I transferred this ...
6
votes
2answers
273 views

IBM would-be purchase of CP/M

It is well-known that on a sunny day in 1980, when the IBM representatives came knocking on the door of Digital Research, Gary Kildall was still in the air on the way back from visiting another ...
6
votes
2answers
650 views

CP/M SKU per CPU only?

The impression I get is that CP/M relied on the BIOS, provided in ROM with the computer, for all the hardware-specific functions. So if you bought CP/M, you didn't have to specify what computer you ...
3
votes
2answers
187 views

Is it possible to get a pdp7 [closed]

Is it possible to get an original DEC pdp-7, if so how much would it be? I've looked around the internet, but I'm not finding anything.
3
votes
2answers
314 views

EGA style 16 color dithering

I am trying to write a program in C# that will re-create the type of dithering used in many of the old sierra and Lucas arts games. I have looked up many different dithering algorithms and none seem ...
8
votes
1answer
834 views

Did CP/M provide compatibility for screen-based programs?

I refer here to 'screen-based programs' that are not actually graphical, but take full advantage of the screen as a two-dimensional array of 80x25 characters, as opposed to typical 'command-line ...
2
votes
1answer
222 views

What was the purpose of GROM (vs ROM) in the TI-99/4a?

The TI-99/4a had a cartridge slot on the front of the computer which accepted "solid state cartridges" (as TI called them). These cartridges would typically contain ROM (Read Only Memory) like many ...
8
votes
1answer
343 views

How can floating point addition be so slow on a BESM-6?

In the BESM-6 technical manuals — for example, in the ALU description, page 4 — there is a table specifying min/max/average instruction latencies in clock cycles (the last 3 columns; the ...
3
votes
2answers
301 views

When were sprites first displayed in the border area?

I assume one of the first undocumented effects on the VIC-II was the ability to display sprites in the (upper and lower) border area. I wonder how and when this was first discovered and used? Was it ...
13
votes
1answer
401 views

Why does AT&T syntax use * and $?

In a comment to an answer about AT&T assembly syntax, another-dave asked the following: DEC used #foo for an immediate operand in -11 assemblers; the Unix guys apparently preferred $foo, which ...
41
votes
13answers
15k views

How was it back then in 1984, when the Apple II had color, and the new Macintosh didn't?

I imagine it being a huge downgrade for some, not to have color on the Macintosh. Macintosh games were black and white in the beginning, while Apple II had color. I'm especially interested in ...
2
votes
2answers
297 views

USB ports for a 486 laptop (pccard 16bits)

I have an old laptop 486 with PhoenixBIOS which supports PC card 16bits( PCMCIA II/III). I am thinking about the possibility of adding a pccard 16bits with USB ports, mainly to read usbsticks or ...
5
votes
3answers
155 views

Opening or converting GFA Basic files to something readable?

There is a bunch of GFA BASIC for Amiga files (the source code for Blender's ancestor, Traces, downloadable here: http://zgodzinski.com/blender-prehistory/) that I would like to peek at. Despite my ...
10
votes
2answers
318 views

How to use the “darker” CGA palette using x86 Assembly?

For those of you retro developers out there, I am having a hard time figuring out how exactly to select the "darker" color palette in 320x200 CGA mode. Here's what I have so far: setup_cga_graphics: ...
17
votes
2answers
2k views

Why did the original Apple //e have two sets of inverse video characters?

According to Apple II Technical notes Mouse #6, updated January 1989, In unenhanced Apple IIe computers, the alternate character set contained two sets of inverse uppercase characters. In the ...
4
votes
2answers
253 views

Why does the Commodore 64 leave these pointers in Zeropage?

I'm trying to decide on what I can get rid of from the zero page, so that I can keep my own data there. Looking at this page, documenting what each of the zeropage locations do, I'm trying to figure ...
4
votes
3answers
561 views

Were some Atari 2600 games written in C?

I thought all Atari 2600 games had been programmed in 6502/6507 assembly language (plus whatever activated the Stella sound system), but at a party recently, a friend indicated that some 2600 ...
3
votes
1answer
273 views

Did any Apple II games use a “timing resistor”?

A science-lab program for the Apple II (I forget the name) had a board that plugged into the joystick port and included a "timing resistor". While I don't know what the program actually did with the ...
26
votes
6answers
4k views

Are there vintage or historical bitmapped fonts available for non-commercial use?

I'm looking for a source for one or a few 1-bit black-or-white bitmapped fonts used in the past, available in a set of sizes. Current incarnations might be available for large LED displays, but those ...
10
votes
4answers
1k views

Did any machines alternate between two video memory banks?

If a home computer or console has two banks of memory, A and B, then the following design is possible: The video chip only connects to bank A. The CPU connects to both. During active scan line, CPU ...
2
votes
1answer
258 views

Why does the SNES have a separate memory bank for sound?

According to https://snescentral.com/article.php?id=0088 the SNES has the following memory banks: Work RAM for CPU - 128 Kilobytes (CPU temp. storage) Video RAM for PPU - 64 Kilobytes (temp. storage ...
3
votes
1answer
180 views

What was the first publication documenting AT&T syntax assembly language?

What was the first publication to document what is (now) known as AT&T syntax assembly language?
2
votes
1answer
288 views

When were other inexpensive computers able to recreate “The Amiga Juggler”? [closed]

The Amiga Juggler was the 2nd very popular demo to appear for the Amiga Computer early in its lifespan. The demo was created by Eric Graham (who went on to develop Sculpt3D) using raytracing to both ...
1
vote
3answers
210 views

Connecting multiple computers through dialup

I have several IBM ThinkPads with an RJ-11 port that can be used for dialup internet connections. Currently I have one ThinkPad connected to a dialup modem, that connects to the internet through a ...
16
votes
2answers
2k views

When TCP was first invented, was the initial sequence number required to be random?

In current time, when a TCP connection is initiated, the initial sequence number is required to be random. But I am wondering, when TCP was first invented, was the initial sequence number required to ...
37
votes
1answer
5k views

How did Super Mario Bros. 3 create this tunnel vision effect?

In a certain section of World 8's map, the screen is black except for a small circle surrounding Mario (as seen below during this speedrun). After doing a little research, I discovered that the game'...
3
votes
1answer
90 views

Exidy Sorcerer: how can I load a program from cassette whilst within CP/M?

I have a file transfer program (sterm) that I want to load from audio cassette, but I need to load it into CP/M. Is this possible? Any suggestions how to do it? When CP/M is running either I don't ...
11
votes
3answers
527 views

Why have “room of dead” in Ultima VII?

http://wiki.ultimacodex.com/wiki/Quirks_of_the_Ultima_VII_Engine vaguely talks about this room being "necessary" to place seemingly "dead" NPCs and it was result of some challenge that programmers had ...
8
votes
1answer
322 views

How did Parallel ATA/IDE Independent Device Timing work electrically?

Back in the days of Parallel ATA (a.k.a. IDE) it was possible to connect two drives with a single cable. The ATA standard defines a number of modes with different speeds which the drives and the ...
1
vote
0answers
114 views

Old grid-based puzzle game with snakes that wake up when on the same row/column as you

I'm trying to find an old game: Played on an old computer, not sure which kind. (early/late 1990s?) Graphics were grid-based and "8-bit-seeming". Locations included - I think - plains and caves. ...
1
vote
0answers
90 views

Old C128 - normal to straight away pull 2 amps? [closed]

I'm trying to get an old C128 working again. Lacking a C128 power supply, I've attached a C64's power supply's 9VAC and am supplying 5VDC from a bench power supply (with a 2A limit at the moment). ...
2
votes
0answers
94 views

Which Nobel prize winners names besides Townes were used as code names for Fujitsu computers?

Fujitsu named its late 80s/90s personal computer FM Towns after physics Nobel prize winner Charles Townes. According to the sources (1, 2) I could find, using Nobel prize winners as code names was ...
3
votes
1answer
180 views

Operating systems (on support or recent) to install on a i486 processor computer [duplicate]

What operating systems would you recommend for this type of hardware? Though I keep the question text generic because answers can work for many others, but my specific case is a Laptop Siemens ...
23
votes
2answers
2k views

How many OS/2 viruses were there?

When I was in college, I remember IBM representatives trying to sell OS/2 Warp to students and teachers by saying that there were no (known) viruses for OS/2. (Of course, that didn't stop the makers ...
6
votes
3answers
367 views

Commodore 64 with red and white RCA cable

After discovering my old Commodore 64 in the garage, I wanted to test if it still works. The power light comes on but the video connection to a modern TV is obviously an issue, as mentioned here. Well ...
3
votes
1answer
381 views

Why did the Atari's have such clear displays?

Anyone that's seen an Atari 400/800 next to a VIC-20 or C64 will know what I'm talking about - the Atari display was much, much sharper. It had a similar advantage over the Apple II, and I seem to ...
5
votes
5answers
558 views

What systems had the lowest resolution ever that still allowed games to be made?

Just for fun, I wrote my own Chip8 interpreter/emulator and it works. The point is that it works in the terminal, meaning that a pixel is rendered using curses and a # character. For the Chip8 that'...

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