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7
votes
1answer
435 views

Was there ever a functional EGA emulator for the Hercules graphics card?

I used to use a CGA emulator (don't remember which one it was), that could show some gfx even in EGA/VGA-only games (when I selected EGA mode). I remember my frustration seeing some garbled graphics ...
9
votes
1answer
354 views

Why do PC DOS kernel files have the COM extension, even though they are not executable as COM files?

The PC DOS kernel is stored in files named IBMBIO.COM and IBMDOS.COM. Although they have the COM extension like executable files, neither of these files could actually be run from the command line, ...
4
votes
0answers
118 views

Where to find ancient wavy cursor program 'cyclops'?

In the period of about 1987-1988 I downloaded a small compiled program from a BBS in the 512 area. I don't know anything about the author but the file was named 'cyclops.' I can't be sure if it had a ....
0
votes
1answer
123 views

What did “double track” meaning in relation to floppy disks?

I mostly used 3½″ floppies back in the day but I also used 5¼″ floppies to some extent on Apple II's and TRS-80's. I was never exposed to 3″ floppy disks as used mainly on Amstrad microcomputers and ...
22
votes
7answers
4k views

Was it possible programmatically to manipulate the volume as well as the pitch on computers with no sound chip?

On early versions of many 8-bit computers like the Apple II, Spectrum, and even the IBM PC, there was no sound hardware other than the simple "beeper". Programmers made sound by hitting a hardware ...
0
votes
2answers
125 views

Can I use a 2.88MB ed floppy disk (3.5in) in a drive that uses the standard 1.44 HD DS disk?

I am using a Windows XP with an old accounting app, that will only back up to a 3.5 in floppy disk. But the backup requires a second disk to complete the job -- a pain. Would a ed 2.88 mb floppy (if ...
2
votes
1answer
142 views

How does the “backwards bump method” of SMB work?

In Super Mario Bros, the screen automatically starts scrolling once you are past X position 112. However, a strategy employed by many speedrunners of the game during level 4-2 is the "backwards bump ...
8
votes
1answer
342 views

How much time and how many people were required to develop Delphi version 1?

I would guess the compiler was primarily a modification of Borland's Turbo Pascal, while the Integrated Development Environment and Visual Component Library required a lot more development from ...
1
vote
0answers
38 views

Transfer a TeleDisk image of a 5.25 disk to a 3.5 disk

I am trying to power on an old Siemens PG675. It need a 5.25 disk but unfortunately it is missing. I found a TeleDisk image (.TD0) of this disk, and I would like to transfer it to a 3.5 floppy disk (I ...
-2
votes
2answers
183 views

Why did computers settle for instructions with multiple machine cycles instead of investing into larger ring counters? [closed]

On the 8080 and 8085 microprocessors, a LDA instruction took 13 timing(or T) states to execute. This could be solved by using a ring counter that could generate said 13 T states,as well as having ...
2
votes
2answers
285 views

How do microprocessors multiply without a “Multiply” instruction? [duplicate]

I was reading about the SAP computers(as I do), and examined the SAP-2 chapter of Paul Malvino's Digital Computer Electronics, hoping to learn about how a microprocessor without a multiply instruction ...
14
votes
6answers
5k views

How is it possible that they used to type “Mb” when they meant “MB” in printed computer magazines in the 1990s?

I've read some English and Swedish computer magazines from the 1990s, even late 1990s, and they frequently (maybe even consistently) use "Mb" to mean "Megabyte", even though "Mb" at least now means "...
7
votes
1answer
132 views

Did the Samsung SPC-650 have any hardware or firmware differences to the genuine Sinclair Spectrum+?

There was a clone of the Sinclair Spectrum+ in South Korea called the Samsung SPC-650 that looks identical to original British version with just an extra model number/logo. It even retains the ...
0
votes
0answers
80 views

Portable 386 that only ever beeps continuously; no video

I've acquired a late-80s portable 386 with builtin LCD in unknown working state. It only ever beeps continuously on boot, with no picture on either the built-in LCD or an external VGA-connected ...
3
votes
1answer
36 views

Is there a Spectrum +3 ROM disassembly available with the addresses of the instructions included?

In my experiments with Spectrum disk formats I've found myself looking into the ROM code a few times. Several Spectrum emulators have built-in debuggers that let me dissassemble and step through the ...
3
votes
1answer
134 views

How to emulate Pocket PC (PPC) 2003?

The OS is at least 17-18 years ago. Yet there is a lot of scattered information and dead ends, and no clarity on how to emulate Pocket PC 2003, the early precedent to Windows Mobile. How to emulate ...
4
votes
5answers
2k views

How does the shift key in a keyboard work?

The "shift" key on a keyboard is different from other keys as it can edit the outputs of the other keys on the keyboard. But how does it do it? I have one hypothesis on how the shift key does what it ...
3
votes
2answers
140 views

Why did the Apple Disk II version 3.3 change the boot protocol?

From what I understand, early versions of the Disk Controller II required that there never be two or more consecutive bit times without a phase transition (which would read as "0") but an upgrade to ...
0
votes
1answer
61 views

keyboard not operating electronica-bk-0100-01

I own a Electronica-bk-0100-01. I have only got around to connecting it up. Before that I opened up the system, checked for bad tracks, obvious issue etc. I also checked the end to end of the ...
0
votes
2answers
101 views

How do I know where the file directory is stored on a Spectrum +3 disk layout?

I'm trying to parse Spectrum +3 disk images. I only ever had a tape-based Speccy back in the day. The +3 had a built-in floppy drive but was late to the party and not that successful. It had the same ...
4
votes
4answers
899 views

How does the Spectrum +3 know whether a disk is bootable or not?

I've been looking through documentation on The Sinclair/Amstrad Spectrum +3 which was the only Spectrum that came with a built-in floppy disk drive. The disk format was based on The Amstrad CPC and ...
3
votes
4answers
366 views

“SAP” microcomputers vs real microcomputers

In Paul Malvino's "Digital Computer Electronics", he labeled 3 theoretical microcomputers which he called the SAPs or "Simple As Possible"s. The point of these 8-bit microcomputers was to teach ...
3
votes
1answer
131 views

Networking WfW 3.11 between modern ethernet and 56k internal modem card

Is there any way i could use either of those networking cards and use them on a modern ethernet system? We have aDSL where i live. If i couldnt connect it to my home network, is there any way i could ...
4
votes
3answers
223 views

How does DRAM refresh work in the Leningrad?

The Leningrad uses the КР565РУ5 chip, which is the same as a 4164. It contains 64kbits of DRAM, and the datasheet says that each of the 256 row addressed need to be strobed every 4ms. I can see how ...
19
votes
2answers
6k views

Why did Socket 3 have more pins than needed for the 486?

Intel's Socket 3, used for 486 processors, was a 19×19 pin grid array socket. However, all compatible processors, to my knowledge, used 17×17 PGA packages. What was the point of the extra pins around ...
4
votes
1answer
189 views

What is the memory layout in MS-DOS

I know that when an .COM file is loaded, DOS loads its contents into memory, sets the segment registers (CS, DS and SS) to point to the 64KB segment and then performs a jmp to the starting address. ...
0
votes
0answers
62 views

Composite video from C64 not being picked up by a modern Smart TV [duplicate]

I've purchased a Commodore 64 "as-is" from eBay. I tediously cleaned out the interior and removed all chips and dusted them out and put them back together. Still, no signal. Except for sound. So, I ...
0
votes
0answers
25 views

Keyboard binding/macro file format for Avant Stellar keyboard

I have a backup of a keymapping/macro configuration from an old Avant Stellar keyboard that was used with some legacy accounting software. The backup is a small .KBD file that I believe contains some ...
11
votes
3answers
2k views

Decoding Logic and Memory Systems for 8-bit computer - 64K address space

I am creating a minimal Z80 computer with serial output on a breadboard. I have kind of moved up from the last question, where I was executing instructions on Z80 using specific connection of ...
6
votes
1answer
118 views

Details of ZS Scorpion port 0x1ffd

There's this page about the ZS Scorpion, and I'm reading about the way bankswitching works. Port 0x7ffd is the same as on western ZX Spectrums, but to double the amount of RAM to 256k and also the ...
3
votes
1answer
163 views

“Genesis Lock-On Technology” to change the language of a Famicom game

I want to create a cartridge similar to Sonic & Knuckles or a Game Genie so that the text files loaded from the ROM or DEPROM of an original Famicom cartridge can be replaced with alternate ...
8
votes
0answers
129 views

What proprietary AT&T code/features were removed in BSD Net1 (/2), and BSD 4.4 Lite (/2) from the original 4.3BSD codebase?

Background Although BSD and its source code was freely available under the original BSD licenses, but it only covered the portion of the code which copyright was owned by Regents of the University of ...
6
votes
1answer
188 views

Did the Timex Sinclair 2068 and the Sinclair ZX Interface 2 use totally different hardware and software techniques?

Sinclair released an add-on for the Spectrum called the ZX Interface 2 that provided joystick ports and a cartridge slot. It wasn't successful and only a few cartridges were ever produced. In the US, ...
1
vote
0answers
68 views

Do we know any estimate of how many Sinclair ZX Spectrums, clones, and compatibles were made in the world?

The original ZX Spectrum was made by Sinclair and then by Amstrad in the UK. There were official versions also in the US, Europe and even India. There were very many clones and compatibles made in ...
0
votes
1answer
57 views

Do any of the open source Sinclair ZX Spectrum emulators support both TR-DOS and 3DOS?

The number of Spectrum emulators has been growing for decades now so there's quite a lot for different platforms and written in different languages. I'm interesting in learning about two of the disk ...
1
vote
2answers
294 views

What was it like to use Windows NT 3.1? [closed]

For those who used it back in the day, what was it like to use Windows NT 3.1 (or 3.5/3.51)? What did you view its pros and cons to be vs., say, the consumer version of Windows 3.1, or heck, against ...
2
votes
0answers
111 views

Algorithm to properly format 360k 5.25" diskette on 1.2M drive?

This is a low level tech question, as I develop the driver for the FDC at its command set level. Having reviewed a number of sources I can not find the algorithm of how to format the 360k diskette ...
16
votes
1answer
3k views

How did large .COM files work?

An MS-DOS .com file is just raw code/data without header, thus no linking information, and was limited to be loaded into just one segment (64kB). That's the reason corrupted binaries would print "...
2
votes
2answers
249 views

Are old Dos and Windows .com executable binaries real mode or protected mode?

Newer Windows and Dos binary executable files with the .exe extension have an MZ header in them and nowadays also a PE header. But before these there used to also be .com binary executable files and ...
1
vote
1answer
126 views

How can I link a BASIC program with BASIC 3.5 for C64?

In the magazine 64er from June 1990 a BASIC extension for running Commodore Basic V3.5 on the C64 was presented. The extension is available at csdb. However, to run a BASIC 3.5 program, it is ...
0
votes
2answers
35 views

Reading 360k floppy disk in 1.2M drive

I formatted several 5.25" diskettes with 360k and 1.2M on the Windows XP PC using 1.2M (HD) drive. I am using the same drive to read data from 360k diskette back using custom driver. The controller ...
7
votes
1answer
194 views

Did the Apple II Integer BASIC use SWEET16?

In the Byte magazine article that Woz wrote about the Apple II (Vol 2, No 5), on page 43's last paragraph he mentioned how SWEET16 was useful and he estimated that about 20% of the Integer BASIC code ...
1
vote
2answers
187 views

Reusing original Palm memory cards

I have a number of non-functional older PalmOS devices (of the 68000 processor variety, not the later ARM processor models). I'd like to be able to reuse the memory cards from these in new ...
2
votes
1answer
136 views

What 20th-century computers besides KDF9 replicated hardware for each concurrently-running program?

The KDF9 (English Electric, 1963) had a hardware option for timesharing. This provided four instances of most per-program context: the nest (16-deep expression evaluation stack), the subroutine jump ...
11
votes
2answers
3k views

In the Intel 8080, where does the “Stack” start?

Having trouble trying to search for this in the data sheet, just have seen how big it is and how it handles stack pointers. Would anyone mind helping me out where the "Stack" start on an Intel 8080?
3
votes
2answers
127 views

How did the Spectrum clones with TR-DOS and paged memory load and run code files from disk?

I've been playing with Spectrum emulators, their file formats and some reverse engineering tools recently. Thanks to this forum, I was able to parse the TR-DOS disk image format and find the bytes of ...
2
votes
2answers
114 views

How do I navigate the boot menu in later model Spectrum emulators?

35 years ago I had an original 48K Sinclair ZX Spectrum. I never had any of the Plus or 128K models and practically never even touched one as I moved onto the Amiga quite early. I'm now playing with ...
7
votes
2answers
458 views

How do you use the INHIBIT pin on the Apple II bus?

Pin 32 of the Apple II bus is a signal called /INH (short for "INHIBIT"). Some of what I found online about using this pin for an Apple II expansion card suggests it was inconsistently implemented ...
2
votes
1answer
120 views

How to force-install Pocket PC (PPC) or Windows Mobile (WM, WinMobile) .CAB apps onto Windows CE

When searching for the apps for these outdated systems, one can often find the apps available for both Pocket PC and Windows Mobile, with minimal or no changes between platforms. Sometimes there is a ...
2
votes
0answers
57 views

How to use Tasword 2 with Esxdos

I'd like to be use the Tasword 2 text editor for the ZX Spectrum to load and save text files on an SD card. Gary Lancaster provides a version of Tasword that uses Residos system calls, but as far as I ...

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