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12
votes
2answers
2k views

Are these ROM cartridges and for what device?

I picked up four of these (what I assume are) ROM cartridges for a console, in a Thai second hand market in Bangkok. None of them have casings: There are three different types, distinguished by the ...
8
votes
1answer
815 views

6502 double store and copy protection?

I was watching a video on netlist simulation of the 6502. The presenter mentions how the 6502 has a double store upon using INCY, and then offhandedly mentions that this can be used for copy ...
2
votes
1answer
143 views

macOS Spaces first appearance under any guise? [closed]

Wikipedia tells me I had to wait until OS X Leopard in 2006 to first use Spaces. It does mention earlier 3rd party structures in an outside reference but the Wayback link quoted doesn't actually ...
23
votes
4answers
5k views

When did half-bad RAM chips stop being available?

The ZX Spectrum sold with either 16 or 48K RAM, necessitating an optional 32K memory bank which was achieved in a characteristically (for Sinclair) cleverly frugal way: with half-bad 64kbit DRAM chips,...
5
votes
3answers
226 views

Apple II: ProDOS, zero length prefix and MLI calls

I have a simple program on my Apple IIc written in assembly language. It starts by getting a filename from the user (just the file name, not the full path), then it opens the corresponding file with a ...
5
votes
1answer
487 views

Hitachi HD630x executable format

Can anyone tell me what executable format the Hitachi HD630x series of MPUs used? I'm looking to disassemble (out of curiosity) a binary for the Hitachi HD63A03XP microprocessor. In case anyone is ...
5
votes
1answer
218 views

Did the Power Macintosh 8500 have accelerated blitting?

Looking at online specifications for the Power Macintosh 8500, I was able to find few details on its graphics capabilities beyond quantity of VRAM and supported color depths, refresh rates, and ...
5
votes
2answers
468 views

NEC PC-88 video mode and resolution in games

I learnt that there are 4 video modes as described on wiki. I came across many games for the PC-88, like Thexder (1985), which are in the aspect ratio of 4:3 and in more than 2 colors. I don't ...
9
votes
0answers
227 views

Killer poke on the Ninendo DS via POWCNT1 register

From GBATEK, writes to a certain I/O port for power management may damage hardware: 4000304h - NDS9 - POWCNT1 - Graphics Power Control Register (R/W) 0 Enable Flag for both LCDs (0=Disable) (...
5
votes
2answers
587 views

What is the reason of the particular range of the last 4K block of memory selection in Apple II

Following my previous question on Identifying the functionality of the memory select in Apple II and now that I know that the memory select device is simply an interconnection block. Searching for ...
6
votes
2answers
481 views

Identifying the functionality of the memory select IC in Apple II

Three are ICs labeled memory select used in Apple II. One to apply A6 on the three banks of RAM ICs. One to generate /RAM_SEL applying the latched RAM output to the data bus. And one to apply /CAS on ...
38
votes
1answer
7k views

What was “the shrinkwrap issue?”

I first read "Alice in UNIX Land" (by Lincoln Spector, Texas Computer Currents, Sept. 1989), probably around the time when it was written — and at that time didn't understand very many of ...
2
votes
0answers
96 views

Running Codenet on a Commodore 64 Emulator

I finally managed to get basic networking stuff working on VICE, thanks to another thread on Retrocomputing. I'm now wondering how to setup a Codenet server emulation. I was able to identify four ...
1
vote
0answers
43 views

How to Perform RR-Net MK3 Detection on VICE Commodore 64 Emulator?

RR-Net documentation describes a detection algorithm for the MK3 model. The algorithm is supposed to reveal the last four hex digits of the MAC address. According to documentation the MAC address 28:...
5
votes
1answer
233 views

Did the Tiger Game.Com include any hardware accelerated graphics?

I stumbled upon screenshots of the Tiger Game.Com handheld running its Resident Evil 2 port and I'm curious to know what its graphical capabilities actually are: (from: https://twitter.com/_Kimimi/...
7
votes
1answer
127 views

Compucolor 2 emulator CCEmu's `.ccvf` disk format

This Compucolor 2 emulator uses disk images with the file extension .ccvf. Here is an example file. I would like to understand how to interpret that format. I understand from the documentation that ...
3
votes
2answers
336 views

Would there be any practical use of two or more VDPs or sound chips in a retro computer build?

Would that allow for better sound samples or double/triple the number of sprites & colours on screen or would that put too much pressure on the CPU or cause bottlenecks, maybe requiring 2 CPUs for ...
6
votes
3answers
1k views

What is the MOS 6502 doing on each cycle of an instruction?

So, first off, I am kind of a noob with emulators and the 6502. Summarise the problem If we for example take the instruction ADC Immediate ($69) which adds the accumulator to an immediate value and ...
6
votes
1answer
299 views

What are the differences between Leningrad-1 and Leningrad-2?

From Planet Sinclair Leningrad-1: A simple and cheap machine, this Spectrum clone acquired widespread popularity. Not very Spectrum-compatible, due to the way the machine was designed. Leningrad-2: A ...
2
votes
0answers
120 views

How many people were employed in the UK making Sinclair computers?

According to Wikipedia Sinclair Research had only 140 employees at its peak in the 1980s. I was surprised the number was so small for a company that sold something like five million computers, then I ...
10
votes
2answers
847 views

What was the communication format of the Edison stock ticker?

Thomas Edison invented the first practical stock ticker in 1869, which is considered to be an important predecessor to teletypes and computer printers. The Wikipedia page for the stock ticker ...
4
votes
2answers
382 views

Would it be possible to run Discord on Macintosh System 7?

I'm toying with the idea of using System 7 as my daily work station at home, most probably via Basilisk II running on some Linux flavour, but possibly on an actual Performa 5200. One piece of modern ...
9
votes
6answers
1k views

What did order processing on a teletype look like?

The earliest business data processing systems were based on batch processing of punchcards. Prepare cards off-line, feed a batch of them through the computer. (Why does one so often hear of payroll, ...
3
votes
1answer
183 views

Porting of software from the m68k family architecture to the DEC VAX

I am looking for impressions, memoirs, articles, guidelines - everything that is possible about the unusual direction of software migration. I am interested in non-Unix related code, and preferably ...
17
votes
1answer
1k views

How did the Nova 1200 divide so quickly?

According to https://en.wikipedia.org/wiki/Data_General_Nova The Nova 1200 executed core memory access instructions (LDA and STA) in 2.55 microseconds (μs). Use of read-only memory saved 0.4 μs. ...
17
votes
1answer
1k views

How did SABRE work interactively without screens?

The SABRE airline reservation system went online in 1964, astonishing the world by being among other things the first large-scale interactive computing system. Once the IBM 3270 video terminals were ...
8
votes
2answers
202 views

Why was the VT05 resolution 72×20?

According to https://en.wikipedia.org/wiki/VT05 the VT05 presented the user with an upper-case only ASCII character display of 20 rows by 72 columns. At first glance this seems a reasonably natural ...
14
votes
5answers
2k views

Advantage of RS-232 over 20mA current loop

According to https://en.wikipedia.org/wiki/VT52 Like other early DEC terminals, the VT50 series were equipped with both an RS-232 port as well as a 20mA current loop, an older serial standard used ...
6
votes
1answer
191 views

What information was present in line printer printout cover/trailer?

Nowadays, in corporate offices where there are typically several office printers per floor, sending a file to a printer does not result in any additional pages identifying the print job, at least by ...
9
votes
4answers
636 views

Delay loop in BASIC

Yesterday I was looking for a way to implement a delay loop on the C64. I came across this page: https://www.c64-wiki.com/wiki/TIME At the bottom of the page there is a code fragment that waits for a ...
3
votes
0answers
102 views

Converting AC'97 to a standard that can be used by my Soundblaster

I currently enjoy using a Windows 98 PC I built using parts I got either for free or very cheap. One of those parts is a sligthtly modern case - the cheapest one I could find that has a 5.25" and ...
2
votes
1answer
198 views

Modern heat sinks for Commodore C64/C128

The VIC-II and SID chips in the C64/128 are prone to over-heating and are rather expensive to replace nowadays. Some other ICs in these machines may have the same issue. An unmodified machine includes ...
5
votes
3answers
943 views

How can I read COM port addresses from BIOS in QuickBasic 4.5?

I have been using the following code to get comm port addresses from BIOS in QuickBasic 4.5: PRINT "Hex addresses for ports 0 to 3 from BIOS." DEF SEG = 0 FOR x = 0 TO 3 z = &H400 + ...
5
votes
3answers
289 views

Modern (cooler) replacements for vintage static RAM chips

The device I'm using (a SYM-1, probably c. 1979) has a stack of L2114-UCE 1024x4 static RAM chips ("2114 static, TTL in/out 1024x4 N-MOS RAM", the -UCE means "450ns access time, 315mW ...
4
votes
2answers
438 views

How much memory does this SYM-1 have?

I have a SYM-1 with the following memory configuration: How much memory is that? Those all appear to be L2114UCE chips, which are described as "Static 1024x4 NMOS RAM", but I'm not sure how ...
0
votes
2answers
219 views

CPU slaves on a PCI card to retrofit single processor to multiple processors. Any ideas how? [closed]

My desktop computer is no longer manufactured and no longer supported since more than 18 years ago. It was a very expensive top of the line business computer back in the day. I like it and wish to ...
7
votes
1answer
1k views

I can't read DS 1MB floppy disks

Using an USB external floppy drive, I've been able to use my Mac to back up files from a big box of 3.5 inch floppies (800K, HD 1.4MB). But I cannot even read my DS 1MB floppies using either the ...
4
votes
1answer
534 views

Sym-1: What is the “f” register?

Running SUPERMON on a Synertek SYM-1, the R (REG) command cycles through a number of registers. Most are self explanatory: p is the program counter (pc) s is the stack pointer a, x, and y are obvious ...
11
votes
2answers
2k views

Intel 386 multiply bug

Some early models of Intel 80386 processors had a bug with 32-bit integer multiplication. Those which were found to have the bug were marked "16-bit S/W ONLY" (not sure what S/W is supposed ...
22
votes
1answer
2k views

Where are the sources of the original curses library?

The curses library is a terminal control library for Unix-like systems used in text based user interface applications. It has been used in many games in the past. It was developed by Ken Arnold and ...
39
votes
8answers
11k views

Why is EEPROM called ROM if it can be written to?

Is there a historical reason? Since it is rewritable it isn't read only by definition, so why call it so?
12
votes
3answers
2k views

What 8086 instructions accept REP?

I tried this code in my assembler, set to 16 bit mode: bits 16 rep mov ds, ax Surprisingly, no error was thrown. Is this even valid? Wasn't rep only supposed to work with string instructions? Is it ...
1
vote
1answer
324 views

What to do with stone age x86 computers? [closed]

Not sure if retro is proper place... I have two old notebooks with x86 processors in the 100s range of MHz. While nostalgics might appreciate them, I'm wondering if there is any proper point in ...
10
votes
1answer
709 views

PET as a terminal

While reading about the SuperPET I just recalled another PET modification. My uni had an 11/780 that I learned FORTRAN on. It used modified PETs as input terminals. This took the form of a modified ...
2
votes
1answer
204 views

What's with the TX-0 punchtape instructions?

The TX-0 has a class of instructions very similar to the PDP-style microprogrammed, operation instructions. Fill the opcode field with all ones, and then select which microoperations you want to ...
6
votes
1answer
159 views

Chaining IRQ's with BASIC & Kernal routines turned off

Having disabled BASIC and Kernal routines I set up an IRQ to run the following code when the raster line reaches 200: .irq1 inc 53280 // change border colour // lda #$ff // clear the ...
5
votes
1answer
237 views

PC 90s 2D Platformer Puzzler Indie Exit Levels With Robot

Platform(s): PC (Used to play on Windows 95/98) Genre: 2D Platformer, Puzzler, Indie, Overcome some square obstacles, Exit to door or portal next level (100 levels approx if not a bit less or more) ...
7
votes
2answers
453 views

Reverse engineering an RS-422 protocol with access to only one device?

I have a console, but not the main computer it's designed to connect to. My goal is to interface this with a (Linux) PC, and hopefully more than just the keyboard. I have never tried something like ...
4
votes
1answer
141 views

Macintosh II ROM Replacement

I'd like to upgrade my Macintosh II to FDHD, I have a SWIM chip (to replace the WIM chip), but don't know how to burn the ROMS. The upgrade process I'm trying to do is described in the book: "...
4
votes
1answer
243 views

Identifying and recovering programs from tapes

A couple of days ago, I was given some old tapes with programs written on them. However, I am having some trouble with them. I do not know what computer they were programed for. After recognising the ...

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