Questions tagged [memory]
For questions about computer memory in a retrocomputing context
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Could today's flash memory be used instead of RAM in 1980s 8 bit machines?
I wonder if this is possible and could be a retro-project? (Not something I would try myself, though)
The bandwidth of flash is surely faster than yesterday's 1980s RAM (?)
Why? One possible ...
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What are the minimum system requirements to run GW-BASIC?
In DOSBox 0.74, I can run GWBASIC.EXE without any problem (DOSBox reports 632 KB of free conventional memory). It is GW-BASIC's version 3.10 dated 01-07-1989 with filesize 72576 bytes. On screen it ...
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When did the PC bus start slowing access to video RAM?
The PC architecture, from the original IBM PC onward, has always been designed around the idea that video memory will be on an expansion card. This was an unusual design decision; most 80s computers ...
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Did anyone use quarter-bad RAM chips?
There was a time in the early 80s when 64k RAM chips had a significant defect rate, such that half-bad ones could be obtained at a discount. Some computer manufacturers such as Sinclair and Tandy took ...
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Did 486 SMP systems provide Total Store Ordering?
Cache-coherent SMP (symmetric, or shared-memory, multi processing) systems can provide various grades of memory ordering guarantees, the stronger ones being more expensive but making it easier to ...
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Did any x86 CPU optionally trap unaligned access?
x86 CPUs have always supported unaligned load/store.
Early RISC CPUs didn't. So imagine writing portable code on a 386. It seems to work fine, but how do you know you haven't accidentally misaligned ...
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Did any 8-bit computers use 16kx4 RAM chips?
An 8-bit computer wanting 64K of RAM, could most straightforwardly use eight 64kx1 DRAM chips (64kbit, 1 data line). The Commodore 64 initially did this, but in the mid-80s, the cost-reduced redesign ...
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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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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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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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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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How did the IBM 360 detect memory errors?
What logic did the IBM 360 use to detect, and perhaps correct, memory bit errors?
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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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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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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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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 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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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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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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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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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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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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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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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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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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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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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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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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