Questions tagged [memory]

For questions about computer memory in a retrocomputing context

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Why did old consoles have special RAM dedicated for a specific task?

Even in the PlayStation/Saturn era, they had like little RAM chips which were dedicated to just "sound", or "video", or "general". Since they still needed to have the RAM ...
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5 votes
1 answer
264 views

How can I resolve these intermittent memory issues?

I own a 1999 IBM Personal Computer 300GL (Type 6275-90U). It's a Slot 1 Pentium III, Intel 440BX chipset, with a riser board for adding PCI and ISA cards and 3 PC100 DIMM memory sockets. About 50% of ...
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1 vote
1 answer
178 views

GBA reading 16-bit values (or instructions) from 32-bit bus

The GBA has various memory sections (e.g. IWRAM, EWRAM, ROM, etc), each with a bus width of either 16 bits or 32 bits. To my knowledge, the ARM7TDMI lacks any cache. When the CPU fetches 16-bit values ...
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7 votes
0 answers
275 views

How can I read from a ferrite memory core today?

I need a little help navigating this ferrite core memory technology. My end goal is to use it in a calculator or something straightforward. I understand the writing process to each core but how is ...
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7 votes
1 answer
749 views

What type of memory was used in N64 and GBA cartridges?

I would like to know if consoles like the N64 and GBA used masked ROMs or some kind of eFuse based ROM, or if they were some kind or flash or EEPROM based memory. I've read that both consoles had ...
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2 votes
1 answer
293 views

When was fixed page size, flexible assignment bank switching patented?

The 8-bit microprocessors invented in the seventies, had a 16-bit address space. It didn't take long for memory demand to exceed this, with the result that bank switching was a fact of life for the ...
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20 votes
5 answers
3k views

How did old computers address far more than 64K of memory despite only having a 16 bit address bus?

I have an old Sharp PC-G830 pocket computer from the '80s that has 32K of RAM and 256K of ROM. I also have a simple single board computer I built with 128K of RAM and a few megabytes of ROM from a ...
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23 votes
8 answers
7k views

Why was computer memory so expensive and scarce?

Computer memory used to be a limited and expensive asset for a long while (for example, in computers with 16KiB RAM or less, compared to the 2 MiB of my first PC (an Intel 486) in 1995 and current day'...
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28 votes
1 answer
6k views

Why did Nintendo 64 (1996) memory cards require a battery inside them to retain data whereas the PlayStation (1994) ones did not?

The Nintendo 64 was released in 1996. Its "Controller Pak"s, which was the name of the memory card that you put inside the controller to save the progress in certain games, require a battery ...
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5 votes
2 answers
721 views

Why did third-party PlayStation memory cards forget/delete saves?

The original PlayStation did not have any writable memory, so you had to buy "memory cards" that were plugged into the front in order to save game progress. Sony sold official cards. But ...
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11 votes
4 answers
1k views

Could the Z80 do interference-free video as the 6502 could?

Technically this isn't just about video since it applies to any regularly scheduled DMA¹ from a non-CPU subsystem, but video is the most common application of this technique so I'll use that as the ...
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18 votes
3 answers
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Did anyone ever put half a megabyte of memory in an Altair?

The Altair 8800 typically, at least in the early years after its release in 1975, operated with no more than a few kilobytes of memory, for the excellent and sufficient reasons that memory was ...
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6 votes
3 answers
449 views

How did Apple IIe software handle 64K bank switching?

The early microcomputers were well served by 8-bit CPUs with 16-bit address bus width, but later generations of these machines tended to run out of address space, and had to resort to some form of ...
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19 votes
2 answers
2k views

Why do drives occupy memory on Amigas

I was reading this question, and it sparked an old memory. I had an Amiga 600 a long time ago. And I used to play Secrets of Monkey Island on it, great game. But then I upgraded the computer and ...
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5 votes
5 answers
549 views

Save state systems

With an Amiga A500, Action Replay cartridge (v1.5 or later) and memory expansion, it was possible to save a copy of the state of memory, much like a save state in an emulator. Were there any other ...
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18 votes
10 answers
4k views

Why did BASIC programs tend to READ a redundant copy of DATA?

Take for example this BASIC version of ELIZA which starts out (in lines 50–170) by a number of READ loops which copy DATA (lines 1340 and following) into a handful of arrays. Isn't this rather ...
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4 votes
1 answer
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How does stack size affect functioning of AmigaOS and programs?

A few weeks back I had an issue with a Python script resetting my Amiga on execution. Someone suggested to change stack size in startup-sequence to 4096. I just read that it can be set up to 2500000. ...
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1 vote
2 answers
174 views

How many kinds of mass-producible ROM is avaliable before 1970? [duplicate]

Back in the days before mask ROM (when invented?) we got core rope memories, or Little Old Ladies memories, which required lots of human labor to build. Were there any kinds of ROMs which were ...
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18 votes
2 answers
4k views

Did any notable product use Intel's first RAM?

The 3101 SRAM was Intel's first product. At $99.50 for 64 bits, it had enough memory to store the characters expensiv. (Sorry, the final e costs extra.) Is there a record of any product using it?
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4 votes
2 answers
299 views

How many 6SN7 tubes did it take to store a bit?

One of the most important components of a computer is a circuit called a flip-flop, which has two stable states (that it can flip-flop between, hence the name); it is used for temporary storage of a ...
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42 votes
11 answers
8k views

How did early laser printers get by with so little memory?

The first HP Laserjet only had 128K of memory. To print an area of 7.5 by 10 inches at 300 DPI requires 844K if it's kept as a single bitmapped image. Obviously they were doing something clever to ...
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4 votes
1 answer
521 views

Building a Memory Management Unit to expand the 16Bit Address space [closed]

I'm in the middle of making an 8Bit computer, I've selected Z80, the 20Mhz version, which is cheap and readily available. Since Z80 has a 16bit address line it can only address 64KB of memory location....
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6 votes
1 answer
700 views

Why does the VICE "load" command skip the first two bytes?

I am studying assembly of the C64, and of course using VICE to do so. VICE has the load command to load data straight into the C64 RAM. I reckoned I could use that to put machine code into RAM and run ...
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6 votes
1 answer
273 views

What were the different RAM refresh techniques in the 80s

I've looked at some techniques that were used at the beginning of the eighties to refresh the RAM (CPU-based refresh for the Z80, or the use of the video circuit for computers that shared the bus ...
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13 votes
4 answers
3k views

CPU frequency / memory wait states at end of the 80s

According to the advertisements of the late eighties, you could find RAM having an access time ranging from 120 to 80 ns (150 to 210 cycle times). A 386SX-25 could execute a typical register to ...
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2 votes
0 answers
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How to get back from RAM1 to ROM after setting the bank bit to 1 [closed]

Mapping more than 64kb of address space regarding cjs answer: How to get back from RAM1 to ROM after setting the bank bit to 1? the next instruction from the program counter would be read from RAM1 ...
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5 votes
4 answers
413 views

Cheapest type of Read-Only Memory allowing Random access before Year 1970

Back in the 50s and 60s people had: random access, read-write memories like Magnetic Cores. sequential access, read-write memories like Delay Lines and Magnetic Tapes. And: sequential access, write ...
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4 votes
2 answers
450 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 ...
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39 votes
8 answers
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?
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3 votes
2 answers
408 views

What high nibble values can you get when you read the 4 bit color memory on a C64/C128?

The C64 and the C128 have a memory for storing the color values of a character. The size of this memory is 1k x 4bit (2k x 4bit for the C128 which can do a double buffering), thus reading the value at ...
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8 votes
1 answer
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Why was the Nintendo 64 bad at textures?

The Nintendo 64 had a reputation for being great at drawing triangles, but not so good at texturing them, so that many games fell back on heavy use of untextured (though Gouraud shaded) triangles, ...
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5 votes
2 answers
883 views

How fast was Rambus compared to regular EDO RAM?

The Nintendo 64 used Rambus RDRAM. This was an unusual choice, e.g. the PlayStation used regular EDO RAM which I gather most consoles and computers did at the time. As I understand it, Nintendo chose ...
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7 votes
4 answers
2k views

Could any computers use 16k or 64k RAM chips?

An interesting feature of the Apple II was that it had three rows of sockets for RAM chips, each of which could take either 4k or 16k chips. That meant the minimum configuration was 4K (cheap) but it ...
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15 votes
8 answers
4k views

Could a Z80 address a total of 128 KB of ROM and RAM?

In a nutshell, could the Z80 address 64 KB of ROM and 64 KB of RAM, or just 64 KB for both RAM and ROM? Unfortunately, I couldn't find an exact and a direct answer to my question while searching. ...
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6 votes
2 answers
871 views

Does the 6800 always handle unaligned access correctly?

I asked a similar question about the Intel 8080 to which I guessed the answer would probably be yes, because later Intel CPUs did fully handle unaligned access. I am less sure about the Motorola 6800, ...
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3 votes
2 answers
900 views

Does the 8080 always handle unaligned access correctly?

The 8080 is referred to as an 8-bit CPU because it has an 8-bit data bus, but there are a number of cases where it must perform 16-bit memory access, for example when reading or writing a 16-bit ...
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6 votes
2 answers
435 views

VAX 11/780 16MB memory board - what was the physical size?

I'm trying to get a feel for what it looked like when you designed a computer to have a lot of memory chips stuffed into it. To that end, I found this: https://commons.wikimedia.org/wiki/File:...
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11 votes
3 answers
2k views

Is this the reason why fread/fwrite has 2 `size_t` arguments?

It just came to me that, the C standard I/O functions fread and fwrite are having 2 size_t arguments because of I guess possibly, that on some systems, there may be more memory of which whose size can ...
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2 votes
2 answers
148 views

How to limit RAM available to Workbench

Is there a way to limit Fast RAM used by Amiga OS 3.1, i.e. if A500 with 030 MMU detects full 64MB in address ranges 0x40000000 to 0x44000000. Instead, can I choose to map only 8MB in lower ranges at ...
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-3 votes
2 answers
431 views

How can 8bits = 1byte but also = 255 bytes at the same time? [closed]

I don't understand why 8bits is defined as being equal to 1byte or 1octet but at the same time the maximum capacity of an 8bit bus or 8bit databus would be 255 bytes because 128 64 32 16 8 4 2 1 1 1 ...
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6 votes
1 answer
372 views

Could the Apple IIGS play any and all Amiga MOD files?

The Apple IIGS has a wavetable synthesis sound chip with dedicated 64 kilobytes of RAM. I assume the sound architecture dictates that samples have to be loaded into that dedicated RAM to be able to be ...
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2 votes
2 answers
253 views

Why isn't this invocation of XMS function Move EMB 0Bh in Turbo C correct?

Following on from my last question, I cannot get Move Extended Memory Block (Function 0Bh) working in Turbo C 2.01. The following main.c contains only the minimum functions: get the XMS driver pointer,...
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2 votes
1 answer
320 views

CDTV Diagrom 1.2 Extended Memory Test AddressError Detected

I've picked up this CDTV some time ago, but didn't have DiagROM to test it properly. It is running perfectly fine, all features. My diag chip arrived this morning, and when I get to Extended Memory ...
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4 votes
1 answer
357 views

How does the GameBoy's Memory Controller MBC1 Work in Mode 1?

In short, are banks 20h/40h/60h accessible in mode 1? The Pan Docs state that when in mode 1, those banks become accessible. "...on large carts (using the secondary banking register to specify ...
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21 votes
8 answers
5k views

Which CPUs, if any, had an 8-bit address space?

Even the Intel 4004, which had a 4-bit word size, had a 12-bit address space. I'm wondering if any commercial CPUs had an 8-bit or similar address-space for programs, data, or both. I'm particularly ...
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  • 471
1 vote
2 answers
215 views

How much memory in this 1040STE system

What is the total size of 1040STE with 4 of these SIMMs installed? How to check the memory using software and which one?
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19 votes
11 answers
5k views

Was it possible to write a novel on a BBC Micro 16kb/32kb memory era computer without expansions?

BBC Micro model B has 32k memory. An average book, like Mary Shelley's Frankenstein, has about 350,000 characters in it. So you'd need over 10 times the memory to load it in, plus the software to edit ...
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  • 299
6 votes
2 answers
306 views

Why was the maximum byte size of 8 bits on IBM 7030?

As far as I know, IBM 7030 used term byte. But this byte was just an imaginary term to make easier for our brain to work with bits. So it had nothing in common with a physical realization of the CPU. ...
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3 votes
2 answers
895 views

Why did IBM 7030 or IBM 360 use byte and word addressing simultaneously

In 1950s machines had a 36 bit words. And in this word we could pack symbols using 6 bits. And to fetch this symbols from the word programmer should do it using bit manipulations. In 1961 IBM released ...
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8 votes
5 answers
2k views

Why did raster displays require semiconductor memory

This source states that introduction of raster graphics display began in mid-1970s only after affordable semiconductor memory had become available on the market. Would it be at all possible to make a ...
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