Questions tagged [memory]

For questions about computer memory in a retrocomputing context

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5
votes
5answers
494 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 ...
18
votes
10answers
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 ...
3
votes
1answer
254 views

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. ...
1
vote
2answers
157 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 ...
18
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2answers
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?
4
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2answers
251 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 ...
41
votes
11answers
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 ...
4
votes
1answer
320 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....
6
votes
1answer
672 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 ...
6
votes
1answer
200 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 ...
13
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4answers
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 ...
2
votes
0answers
93 views

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 ...
5
votes
4answers
371 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 ...
4
votes
2answers
445 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 ...
39
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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?
3
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2answers
346 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 ...
8
votes
1answer
669 views

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, ...
4
votes
2answers
520 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 ...
7
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4answers
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 ...
15
votes
8answers
3k 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. ...
6
votes
2answers
848 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, ...
3
votes
2answers
862 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 ...
6
votes
2answers
374 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:...
11
votes
3answers
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 ...
2
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2answers
143 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 ...
-3
votes
2answers
391 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 ...
6
votes
1answer
273 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 ...
2
votes
2answers
219 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,...
2
votes
1answer
235 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 ...
3
votes
1answer
248 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 ...
20
votes
8answers
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 ...
1
vote
2answers
177 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?
19
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11answers
4k 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 ...
3
votes
2answers
213 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. ...
3
votes
2answers
862 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 ...
8
votes
5answers
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 ...
4
votes
2answers
552 views

Aside from legacy systems, are there any contemporary uses for magnetic core memory?

Core has some interesting properties (nonvolatility, high reliability, resilient to radiation) that might make it useful in some situations. I know early versions of the computers on the Space ...
4
votes
1answer
135 views

How was the second bank of Apple IIc ROM accessed?

The original Apple IIc had a 27128 16 KB ROM mapped into the $C100-$FFFF range (the $C000 page was decoded for I/O). According to the Apple IIc Technical Reference Manual the ROMEN1* and ROMEN2* ...
14
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3answers
506 views

Was the Commodore 128 movable zero page / stack and second block of color RAM actually used?

The Commodore 128 hardware allowed two things that weren't possible on the C64: Moving the 6502 zero page and 6502 stack to another place in RAM besides pages 0 and 1, and switching the CPU and/or the ...
11
votes
3answers
1k views

How can I access/use memory outside of the standard 1 MB address range of MS-DOS?

How do you access more memory (above the 1MB) in DOS if the 640KB of conventional memory are not enough? I have read a lot about this, but I couldn't figure out how to do this in actual code. Is ...
4
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7answers
489 views

Static memory partitioning

Does anyone know of any operating system that used static memory partitioning: contiguous physical memory allocation with one process per partition, one partition per process, partitions generated at ...
5
votes
1answer
730 views

How much memory did the PlayStation development kit have?

The PlayStation 1 had two megabytes of main memory, one megabyte of video memory and half a megabyte of audio memory. Squeezing everything to fit into these limits was one of the big challenges of ...
26
votes
4answers
4k views

Why was it common to reference memory locations using negative numbers on some BASICs?

If you had an Apple II, it was common in BASIC to reference memory locations above the 32K point by using a negative number. For example, if you wanted to click the speaker you would PEEK/POKE -16336 ...
4
votes
1answer
405 views

How wide were the RAM chips in the PlayStation 1?

In earlier years, it was common for DRAM chips to be one bit wide, so that an 8-bit machine would use eight of them to form one memory bank. Occasionally, 4-bit-wide chips would be used, e.g. the ...
2
votes
1answer
249 views

What were the wholesale costs of 256kbit vs 1Mbit DRAM chips in 1994?

In the early eighties, 64kbit DRAM chips replaced 16kbit ones by being cheaper per bit. Around 1987, 256kbit replaced 64kbit in turn, so computers like the Commodore 64 started using two of them for ...
10
votes
1answer
1k views

What sort of RAM chips did the Commodore 64 use in 1994?

For the first few years after its release in 1982, the Commodore 64 used eight RAM chips of 64kbit each. In the late eighties, it became cheaper to use a pair of 256kbit chips of the 4-bit-wide ...
8
votes
2answers
394 views

In an Apple IIc, how is memory beyond 128K addressed?

I always thought than in a memory-expanded Apple IIc fitted with firmware version 3 or 4 and an Apple-built memory expansion, the extra memory above and beyond the first 128K is connected in a way ...
10
votes
3answers
1k views

Cost of dynamic versus static RAM in the early days

Early pioneers building memory cards for personal computers, tended to use static RAM, because it's quite a bit easier to get to work. Later, dynamic RAM became de rigueur, for the simple and ...
9
votes
3answers
2k views

Did multiplexed address/data lines make memory access slower?

Looking at the pinout of e.g. the 8088, it multiplexes the data lines onto eight of the address lines; presumably the designers judged that being able to squeeze the chip into a 40-pin package, would ...
0
votes
1answer
596 views

Get himem.sys working on an AMI 1.06.09 bios (not on VM)

I tried many 98SE boot disks online, they all boot successfully on my mobile workstation from USB (C:\>), but all can't run the Windows 98SE Installer because of XMS Memory, giving an error like: ...