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21 views

System 7.5 install fails (mac IIsi)

I have been restoring a rather iconic (and temperamental!) Mac IIsi. I have trouble installing System 7.5 on an IBM drive with Apple firmware that OS 7.0 installed just fine on. I am puzzled by the ...
14 votes
2 answers
432 views

Raytheon 704 mini uses?

I came across this little machine in a roundabout fashion - 4kW of RAM and 1usec cycle for "under $10,000"! (not including ASR33) It seems this is largely lost to history. Does anyone know ...
3 votes
1 answer
80 views

Is there a routine like FETCH, STASH and SWAP for transfering data between memory bank 0 and 1 on the C128?

The BASIC 7.0 of the C128 provides commands for copying a block of bytes between an REU (RAM expansion unit) and memory in Bank 0 or 1. For those who do not own an REU, is there a function for copying ...
1 vote
1 answer
239 views

Why does Windows 95 not install so well from a Windows XP boot floppy? [closed]

First, the anecdote that inspired this question. Several years ago, I got the itch to try and install Windows 95 in a VM on my Windows 7 laptop. I had very little idea as to what I was doing at the ...
2 votes
3 answers
601 views

Efficiently defining a C function by given address in cc65

I have a function that should be callable with the following syntax: void __fastcall__ initSIDplayer1(uint8_t a); The __fastcall__ modifier here means that the argument is passed in the Accu instead ...
1 vote
1 answer
130 views

74'181 missing zero flag but strange -1 (or all 1) flag, only makes sense in active-low mode?

Out of the popular but closed question 74'181 ALU why would anyone (have) use(d) these wild functions? I break out one aspect, that of a missing zero flag output. If I wanted to build a CPU with ...
2 votes
1 answer
80 views

74181 in odd carry logic in active high mode

Out of the popular but closed question 74'181 ALU why would anyone (have) use(d) these wild functions? I break out one part. I don't get the carry logic. Normally your addition works by giving A + ...
22 votes
2 answers
3k views

What are the "Screen Holes" in Apple II graphics?

I've read the term screen holes many times in the context of Apple II graphics. From what I understand, it has something to do with the interleaving storage of graphics (or was it text) and that some ...
6 votes
2 answers
372 views

SciTech's SVGAKit seems to be incomplete

I'm trying to get into MS-DOS development for fun, and I'd like to use SciTech's SVGAKit library. The last version of it is still downloadable via the Internet Archive here. However it seems to be ...
8 votes
2 answers
639 views

74'181 ALU why would anyone (have) use(d) these wild functions? [closed]

Got myself a bunch of 74LS181, because they were cheap and they have been used in the VAX 11/780. And now I made myself a little tester breadboard where I am trying to figure this out in practice. My ...
3 votes
0 answers
107 views

Did any Dreamcast VMUs/memory cards have more than 200 blocks?

Dreamcast VMUs can store 128k in 200 "blocks". Third party memory cards increased the storage by having multiple virtual cards, each with 200 blocks. With some hacking it is possible to free ...
1 vote
0 answers
142 views

Real applications for the "weird" functions of the 74181 ALU? [duplicate]

Out of the popular but closed question 74'181 ALU why would anyone (have) use(d) these wild functions? I break off another part. We know why those many logic function exist. I am not listing them ...
11 votes
3 answers
8k views

Was the IBM 5100 ever used for codebreaking?

There's a rumor that there's something embedded in the IBM 5100 which makes it useful for codebreaking. What is the legitimacy of that claim?
2 votes
0 answers
161 views

TI-99/4a RF modulator, fuzzy video

I recently purchased a TI-99/4a. Well, 2 actually. Both work, but I only have one RF modulator. I ordered a composite adapter, but that hasn't arrived yet. Both work on the RF modulator, but the ...
2 votes
2 answers
158 views

How do I save data from a program with CC65 [closed]

I wanted to have a calculator program be able to save a set of answers on a floppy disk or tape but I have no idea what I should do. I am aware that the "cbm.h" library can be used to load ...
11 votes
3 answers
2k views

At what point did computing go from mainly performance- and functionality-oriented to security-oriented? Why? [closed]

Back in the early days of (at least personal) computing, it seems like security wasn't much of a concern at all. Pretty much everything ran as "administrator" (or whatever the equivalent was ...
18 votes
2 answers
3k views

What is the oldest reference to PEEK, POKE, and USR?

I've been reading manuals for BASIC implementations and the earliest reference I can find to PEEK, POKE, and USR is in the Altair BASIC 3.2 manual, published in 1975. This morning I came across this ...
5 votes
0 answers
128 views

How many CP/M-86 copies were sold?

Approximately how many CP/M-86 copies or licenses did Digital Research sell across the product life of the operating system? Are there any data or estimates? I know the success of MS-DOS didn't leave ...
28 votes
3 answers
3k views

What exactly did the "UNFORMAT" MS-DOS command do?

I found only this: The UNFORMAT command is used to undo the effects of formatting a disk. The command is available in MS-DOS versions 5 and later. Source: https://en.wikipedia.org/wiki/...
19 votes
3 answers
5k views

Windows 98 setup preparation hangs at 100%

I am trying to install Windows 98 on a pretty modern computer, from 2010. Why? Because I want to see if I can. Anyway, I am booting off a USB flash drive with FreeDOS on it. I formatted the USB flash ...
37 votes
8 answers
12k views

Why do articles use the term "UART" instead of "serial port"?

I am learning about old computers, and I have found the following image from this article: They use the terms "UART" instead of "serial port" and "UART driver" instead of "serial port driver", I have ...
15 votes
4 answers
1k views

Video playback software/formats for a 386?

Wanting to have my 386DX @ 20MHz play a video (any video), just as a demo. I'd prefer it to be watchable (eg 10fps and not a tiny 10x10 pixel) as opposed to a slideshow. What player software could I ...
6 votes
3 answers
452 views

Original NES from UK, that I want to work in the US

I have an original NES from England that I bought in the early 90s. I just found it again in the attic, and I want to hook it up and start playing it again. However, I now live in the USA and it's ...
3 votes
1 answer
181 views

Interpreting TRS-80 model 1/2 tape cassette audio

I got interested in writing my own code to parse tape cassette formats for a few platforms. I did OK with both Spectrum and Apple 2 tapes based on info I could find online. Speccy and Apple 2 seem to ...
11 votes
2 answers
2k views

How does MS-DOS 6 cache the DIR results?

I was wondering how the MS-DOS 6 DIR command works. I noticed that the floppy drive directory is cached so that the drive isn't read again when you run DIR a second time. In thinking there may be a ...
4 votes
2 answers
178 views

Drive icons for LaCie Tsunami

I am restoring a LaCie Tsunami 240 external disk for the Macintosh. I found a replacement Quantum LPS240 and the hardware side is well on its way. This drive displayed a custom icon in System 7 (a ...
23 votes
8 answers
3k views

Which BASIC interpreters support techniques for hybrid programming in Assembly?

It was common with Commodore BASIC (and others, I'm sure) to have machine language encoded in BASIC programs using POKEs or READ/DATA. This was needed for both performance and to access certain ...
46 votes
5 answers
11k 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-...
29 votes
5 answers
4k views

What made some 8-bit BASIC interpreters especially slow?

Most 8-bit systems had a BASIC interpreter that ran at a rate roughly commensurate with the CPU type, speed, memory bandwidth and interrupt status. Some systems, however, had interpreters that ran at ...
14 votes
4 answers
2k views

What is the Circuit for a 16K or 32K MSX computer cartridge?

This question is about the old MSX-1 computers. I have a game I wrote, as a ROM file, and I now want to play it on a real MSX computer by putting the game into cartridge form. The game has been ...
8 votes
1 answer
386 views

Looking for an 8-bit microcomputer with a hardware-accelerated database

In some old video on YouTube a few years ago, I noticed a curious computer from the end of the 70s - early 80s. In the rack (half height), typical of minicomputers of those years, there was a 14" ...
17 votes
2 answers
4k views

What is this diskette drive?

I am preparing a BBC Model B micro computer for sale which has been in storage and needs cleaning. There is a 3½" diskette drive with it, which was unfortunately stored with the slot uppermost ...
0 votes
0 answers
107 views

Laser FD-100 5.25 drive isn’t working?

I recently inherited an apple IIc plus computer and it came with a 5.25 Laser Fd-100 drive. I noticed it wasn’t working so i opened it up and noticed the laser reader wasn’t moving across the tracks. ...
24 votes
4 answers
2k views

Which (micro) computers were dominant in Australia and New Zealand in the 1980s?

Australia and New Zealand are somewhat unique among large, developed, economies because they bridge the culture of (mostly) the West with the geography of the East. I am curious how this may have ...
14 votes
1 answer
2k views

What are Hollerith machines?

While going through the memoirs of a witness of the Holocaust in Germany, I stumbled upon the passage: there in Rudolfstadt we had a new holorydmachine from the Americans - in the barn of a farmer -...
17 votes
1 answer
2k views

Why would installing a 486DX2 make the system freeze for minutes on boot?

In the mid-1990s, a friend of mine had one of those Compaq Presario desktop PCs that had an integrated CRT SVGA display built in the same cabinet as the CPU, in a similar fashion as the early iMacs. ...
9 votes
1 answer
256 views

When was let introduced to Lisp?

Similar to When was DEFUN added to Lisp? when was let introduced? It seems like a fundamental feature but unless I missed something even maclisp didn't contain it.
5 votes
1 answer
123 views

How to avoid error when a macro package is included multiple times in ca65 assembler

Using the .MACPACK directive, predefined macro packages can be included in the assembler source code with .macpack name. For example .macpack generic defines macros like add, or sub (see https://cc65....
8 votes
2 answers
2k views

Which order does the 6502 read its vectors in?

I'm looking at gianlucag/mos6502 and Mike Chambers' fake6502. They have observable differences in the way that they read the reset vector. Rubbermallet reads the $fffc first, and then $fffd. I'm ...
1 vote
0 answers
116 views

How can software including drivers be moved from one windows (2000) installation to another?

I have a Windows 2000 system which no longer boots. We've narrowed it down to disk corruption of some Windows components, and a clean install of Windows should fix that. But there's some specialist ...
3 votes
0 answers
110 views

Can MAME save to cassette tape formats other than WAV? [closed]

MAME seems to be extremely unintuitive to use and extremely poorly documented. But it supports a ton of machines, some of which I haven't found other emulators for, so I've been persevering with it ...
66 votes
1 answer
4k views

How do I extract the program from the Radiohead "Nude" tribute by James Houston?

One of my favorite videos ever is a tribute to Radiohead "Nude" by James Houston. I have never seen the program in the video available to download, so I've just made an attempt to extract it myself. ...
7 votes
2 answers
1k views

Can you load machine code programs for cassette tape on a TRS-80 model 1 level 1?

I'm trying out TRS-80 model I/III emulators. I know there was Level 1 and Level 2. I think this refers both to the ROM and the BASIC on the model I. Level 2 ROMs were a common upgrade to the model I ...
1 vote
2 answers
498 views

Why are computer bus sizes integer multiples of the size of a byte, and when was that standardized? [closed]

Memory is organized in powers of two: 8 bits to a byte, then 16 bits to a short, 32 bits and so on. Some early computers did not necessarily have powers of two as their basic memory unit. When did it ...
1 vote
2 answers
99 views

Dump Mask ROM on MAB8421

I am trying to find a way to dump the rom contents of several MAB8421 microcontrollers. I know that on many 8048 MCUs, you can use the external access pin to dump the rom, but the 8421 doesn't have ...
6 votes
2 answers
384 views

BASIC : POKE and PEEK prohibited on the same line?

Having been raised on an 8-bit Commodore, I was never afraid of PEEKs and POKEs. I remember trying to accomplish something on a computer, in BASIC, using PEEKs and POKEs, and discovering that this ...
6 votes
1 answer
773 views

Can I use a volume wheel with different specs for the GBA?

I bought a replacement volume wheel for the GBA. There are no other potentiometers available for the GBA. The original one has 30 kΩ as shown on the schematics. The one I bought has 10 kΩ and can be ...
2 votes
2 answers
199 views

Is the volume wheel value wrong on the GBA schematics?

This GBA schematics says the GBA volume wheel (VR2 at the center bottom) is 30k ohms. Another schematics can be found here and it also says 30k. However when you do a ebay.com search for GBA ...
9 votes
1 answer
555 views

x86 PC/Dallas Semiconductors RTC style general purpose NVRAM usage

The RTCs of x86 PCs commonly include some amount of general purpose NVRAM, e.g. the DS12885 has 144 bytes general purpose (GP) NVRAM. The ACPI Specification specifies some RTC also with GP NVRAM, ...
3 votes
1 answer
174 views

How to change graphics modes from BASIC on a Timex/Sinclair 2068?

I've got the Timex/Sinclair 2068 emulation working under MAME and wanted to play with its extra graphics modes the original version of the Sinclair ZX Spectrum didn't have. But despite an hour of ...

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