Questions tagged [memory]
For questions about computer memory in a retrocomputing context
184
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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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What happens if a 32-bit compiler receives a over-the-limit 64-bit source code? [closed]
Suppose I need to allocate a statically-sized large structure, with many array members exceeding the limit of a 32-bit compiler when combined totally. What would happen?
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8
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2
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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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19
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4
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Why did the Cray-1 have 8 parity bits per word?
According to https://en.wikipedia.org/wiki/Cray-1
The Cray-1 was built as a 64-bit system, a departure from the 7600/6600, which were 60-bit machines (a change was also planned for the 8600). ...
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27
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7
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Did anyone ever run out of stack space on the 6502?
Unlike its main rival the Z80, the 6502 had a size limit of 256 bytes for the hardware stack. That sounds like a very tight limit, but in my experience, it was never actually an issue; by the time you ...
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13
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2
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Simple doubling of ZX80 RAM
Many moons ago when I owned a ZX80, I remember (or possibly mis-remember) seeing a simple way to double the RAM to 2K by simply piggy-backing two extra 1Kx4 chips on top of the existing two (with pin-...
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8
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1
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Did the Vic-20 save money using static RAM?
The unexpanded Vic-20 had 5K of RAM. This was quite small even by 1981 standards, but it was trying to be cheap enough for consumers to buy, and it succeeded, selling over 2 million units.
One reason ...
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13
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3
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How did the Fairchild Channel F provide a 2K frame buffer?
The Fairchild Channel F, released in 1976, was the first modern game console, in the sense of being the first one to accept games as software, rather than just modular configuration switches.
Looking ...
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2
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Was it possible to give an Atari 800 (not XL) 64KB of RAM?
The original Atari 800 could have up to 48K of RAM installed through the use of memory cards. When the 800XL came out, it was now possible to have up to 64K of RAM by disabling the BASIC ROM.
After ...
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8
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2
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How did the IBM 360 detect memory errors?
What logic did the IBM 360 use to detect, and perhaps correct, memory bit errors?
- 213k
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1
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What did it cost the 8086 to support unaligned access?
The Intel 8086 supported unaligned loads and stores of 16-bit data, e.g. mov ax, foo was guaranteed to work even if foo was odd.
What did this cost, in terms of performance and chip area, compared to ...
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4
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4
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Where are the memory controllers for IBM 5150 or Altair 8800?
Wikipedia page for memory controller states that memory controllers are either part of the northbridge, or in more recent cases, integrated into the processor.
But AFAIK, neither IBM 5150 nor Altair ...
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1
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What is the motherboard part number for the Macintosh IIci that required parity memory?
This is an extension of an answer I posted years ago to the Retrocomputing question:
How did Apple fail to tap the business and scientific markets?
Most (all?) IBM PC systems required parity memory, ...
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4
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How does the Apple II address more than 128KB of RAM?
For the Apple //e, it was very common to have an extended 80-column card installed which brought the machine up to 128KB of RAM via 2 banks of 64KB each. There are soft switches in the $C0xx space ...
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33
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1
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Why did DOS-based Windows require HIMEM.SYS to boot?
My understanding is that all versions of Microsoft Windows that ran on top of DOS — that is, the lineage from Windows 1.0 up to Windows ME, even though the reliance on DOS diminished over time — ...
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3
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When did CPUs start using page mode DRAM?
According to https://en.wikipedia.org/wiki/Dynamic_random-access_memory#Page_mode_DRAM
Page mode DRAM is a minor modification to the first-generation DRAM IC interface which improved the ...
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Why does my Epson HX-20 apparently have much less RAM than expected?
When I enter:
STAT ALL
On my Epson HX-20, I get the following output:
P1: 419 Bytes
P2: 86 Bytes
P3: 0 Bytes
P4: 0 Bytes
P5: 0 Bytes
RAM FILE 256 Bytes
MEMSET 2624
105 Bytes Free
As I ...
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22
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11
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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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Why did Windows 9x allow ring-3 software to change IDT?
I was researching how old Windows 9x viruses, such as Win95.CIH, got ring 0 access, and it's shown that one of the approaches was to get the Interrupt Descriptor Table, hook the interrupt handler and ...
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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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How did the X-Men game for Sega Genesis have its state survive a console reset?
The Sega Genesis system had a rather interesting game. X-Men (1993) was based on the popular cartoon version of the comic book series. But it had what was still one of the most unique (and unintuitive)...
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How to use all memory on an IBM PC with 8086
I'm developing software for the IBM PC with an 8086 processor. I want my program to use all available memory.
I know that I can use DOS int 21h function AH=48h to allocate all available conventional ...
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How does POST memory test work on a relatively modern (2000s) PC? Does it still test every single byte like on older ones?
I have an Asus eee 4G (AMI BIOS), I want to ask if this product actually overwrites the entire RAM during cold boot. I have the "Quick boot" feature turned off and I can see the memory being ...
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MS DOS 6.22 hangs on modern hardware after loading HIMEM.SYS
I am trying to run MS-DOS 6.22 on modern hardware. I successfully created bootable flash disk with MS-DOS 6.22. But when it starts with HIMEM.SYS enabled in CONFIG.SYS it hangs. Searching Internet the ...
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Is it possible to corrupt a Nintendo 64 save file by turning off the console when saving to the cartridge?
All consoles with memory cards (including Nintendo 64) kept reminding you that it's very important to not turn off the power while it's saving, because this would corrupt the save file.
But for the ...
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13
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2
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Why does the FRE() function in CBM BASIC v2 return negative values?
On Commodore machines featuring CBM BASIC v2, the FRE() function to query the amount of memory available to BASIC returns a negative number when the result exceeds 32767 bytes:
This quirk does not ...
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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 ...
12
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3
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How can I read from a ferrite core memory 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
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How can you run a program that is bigger than RAM?
Suppose you have a program that is 218 words long. However you are using a 16 bit machine and have 216 words of RAM. (The RAM is directly addressed by the CPU). On the other hand, you have unlimited '...
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What did game programmers and journalists mean by a "hardware trick"? [closed]
Recently, I've been hearing a good deal about hardware tricks. For instance, the YouTuber Ahoy (see A Brief History of Graphics) mentions that some game programmers resorted to "hardware tricks&...
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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 ...
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2
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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 ...
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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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Status of brute forcing all possible memory states of a video game [closed]
For an old video game that has a small enough memory footprint, it should be possible on exponentially larger modern systems to create a graph of all possible states of memory and the inputs that ...
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Z80 and video chip contending for random access
Back in the 8-bit days, I used 6502 computers, where the story about memory access was easy to understand. RAM chips of the late seventies and early eighties could do 2 MHz (or a bit more e.g. 2.6 in ...
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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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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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0
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2
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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:
...
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How did the ZX80 store both a useful program and screen memory?
I have a vague recollection from my earliest days that the ZX80 only shipped with 1K of RAM.
If this RAM was used to store both the program and the contents of the 32x24 screen, wouldn't that mean ...
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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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1
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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 ...
- 213k
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Windows 98 with 2GB of RAM
I have assembled a retro-gaming PC out of an old Shuttle SN45G with a Windows 98/Windows XP dual boot.
The motherboard can handle 2GB of RAM, but apparently Windows 98 can only handle 1 GiB.
Windows ...
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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 ...
- 213k
2
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1
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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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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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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'...
5
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2
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952
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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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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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21
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3
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5k
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What is causing the problem with the RAM in this (claimed) Spectrum 48k?
I bought what was claimed by the seller to be an Issue 4S Spectrum 48k.
I tried loading games and some worked while others didn't. Turns out it was the 16k ones that worked and 48k didn't. This ...
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Testing RAM on an OmniBook 300?
I've got an old 386 laptop - specifically an OmniBook 300 - and I'm a little suspicious of the RAM. It's exhibited some very odd symptoms, such as memory-related crashes and boot failures, so I'd like ...
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