Questions tagged [memory]

For questions about computer memory in a retrocomputing context

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3
votes
2answers
297 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 ...
6
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0answers
289 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, ...
5
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2answers
417 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 ...
6
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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
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7answers
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
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2answers
833 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
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2answers
839 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
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2answers
339 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
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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
134 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 ...
-1
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2answers
307 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 ...
5
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1answer
222 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
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2answers
191 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,...
1
vote
1answer
88 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
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1answer
176 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
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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
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2answers
150 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
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2answers
198 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. ...
2
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2answers
817 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
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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
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2answers
383 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 ...
3
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1answer
106 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* ...
13
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2answers
339 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 ...
8
votes
3answers
935 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
465 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
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1answer
568 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
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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
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1answer
298 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
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1answer
227 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
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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
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2answers
321 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
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3answers
891 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
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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
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1answer
532 views

Get himem.sys working on a 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: ...
3
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1answer
141 views

How long would a 41256 take to do 4 accesses in fast page mode?

I have been surprised at how little use eighties computers made of fast page mode access to RAM. (A notable exception being the Sinclair Spectrum, which used it to get the necessary bandwidth to video ...
1
vote
4answers
168 views

Will any modern EEPROM programmer work with the IP3604/КР556РТ5?

Just to say I'm completely new to the world of PROM and I'm a bit bewildered. My ultimate aim is to be able to program these Russian 4k bipolar PROM chips, which are the equivalent of Epson IP3604, ...
5
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9answers
596 views

Were there any games/software that used memory beyond what was advertised available to BASIC on the machine?

Were there any games/software that used memory beyond what was advertised as available to BASIC on the machine ? On home / personal computers any time up to 1984 . Without needing to plug in any ...
24
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1answer
3k views

What is a dropfile?

After reading Charles Duffy's comment on Was there a clearly identifiable "first computer" to use or demonstrate the use of virtual memory?: I had a computer science professor around 1999 ...
11
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2answers
850 views

What's the difference between the DOS HIMEM.SYS and the Windows 3.x version?

An installation of DOS (e.g. MS-DOS 5.0) will typically include a statement in its CONFIG.SYS such as DEVICE=C:\DOS\HIMEM.SYS. When installing Windows 3.1, it's setup comments (REMs) that line out, ...
14
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1answer
1k views

What manages Upper Memory Blocks (UMBs) in MS-DOS?

I had always assumed that EMM386.EXE was responsible for managing the Upper Memory Blocks - UMBs - the memory space between 640KiB and 1MiB in real mode x86. For example, on MS-DOS 6.22, help emm386....
8
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3answers
489 views

what is DMA and how does it work?

I've heard the term 'DMA' being used a lot in reference to older consoles. My very basic understanding is that it's a way for the console to access memory directly. But directly as apposed to what? ...
4
votes
1answer
915 views

How did “RAM” cartridges for the C64 work?

Section 7.1.1.2 of the VICE manual mentions that cartridge slot 1 (of the four slots 0, 1, Main and I/O) in the emulator is special in that it's designed to support "mostly RAM-based cartridges" (of ...
6
votes
1answer
245 views

Why does my Amgia 3000 show no Fast RAM even though the ZIP sockets are populated?

I am trying to get an Amiga 3000T up and running, all seems good but there's no Fast RAM. All Zips ard populated. Is there any (easy) way to test the ZIPs? Also, could something like a bad cap kill ...
15
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1answer
714 views

Under what circumstances would RAM locations 0 and 1 be written and/or read on the C64?

To be clear, I'm talking about the actual memory cells at addresses $0000 and $0001 in the DRAM chips. Devices can of course initiate read or write requests to these address on the address/data buses ...
39
votes
4answers
8k views

When did computers stop checking memory on boot?

I remember my old 8088 used to do this (640K OK) but can't remember seeing anything like this since. Does this still happen and it's just not visible? If not, when did it stop, and why? (Imagining ...
30
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1answer
3k views

Did DOS zero out the BSS area when it loaded a program?

As an example, say we have a DOS MZ EXE file that's around 20 KiB in size. The EXE header contains the value 0x1400 at offset 0x0A indicating that the program is requesting 5,120 paragraphs (or 80 KiB)...
13
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1answer
369 views

How did restarts resolve parity errors triggered by broken core-rope wires?

In his account of the history of the Apollo Guidance Computer, Don Eyles describes the role of a parity bit as follows (p. 80): ... if one of those hair thin wires in our woven core-rope memory ...
4
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1answer
336 views

Was there any VIC-20 expansion to bring memory beyond the default maximum of 40 KiB?

The Commodore 64 was very flexible in terms of how RAM could be controlled. ROMs and I/O devices could easily be swapped out by setting bits in the first two addresses of memory. The VIC-20's ROMs and ...
11
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3answers
2k views

On a Gameboy, what happens when attempting to read/write external RAM while RAM is disabled?

According to the GBdevwiki: 0000-1FFF - RAM Enable (Write Only) Before external RAM can be read or written, it must be enabled by writing to this address space. It is recommended to disable ...