Questions tagged [rom]
For questions about Read Only Memory.
85 questions
34 votes
2 answers
3k views
Why did the 8087's constant ROM contain the value ln(2)/3?
In the post Extracting ROM constants from the 8087 math coprocessor's die , the constant ROM from the Intel 8087 was reverse engineered and all 42 constants extracted. One of these constants is 1....
- 2,471
1 vote
1 answer
183 views
ROM chip width to match 18-bit CPU [closed]
Early microprocessors typically had data bus width of 8 bits. Dynamic RAM chips were typically 1 bit wide, used in rows of 8, but mask ROM chips were typically 8 bits wide. As I understand it, this ...
- 65.4k
15 votes
1 answer
392 views
Looking for information on the original Kwikstart for the Amiga 1000
I recently acquired an A1000 that has a Kwikstart card installed. This was a hardware modification (made by DKB Software) that allowed the Amiga to kick from the supplied ROMs instead of requiring ...
- 11k
13 votes
2 answers
2k views
What is the origin of corruption in ROM memories?
Since I am studying the Datamaster, I have seen that a large amount of the remaining units have ROM issues. Basically, along with the keyboard, the power supply and capacitors of the RAM boards, it is ...
- 2,298
1 vote
3 answers
955 views
What is the layout of Atari VCS/2600 ROM files?
I understand the CPU had fewer address lines than a 6502, limiting it to 8kb but that the Atari hardware didn't connect one line thus limiting cartridge access to 4kb. I further understand that the ...
- 8,214
4 votes
1 answer
484 views
How to find the dos.library functions in an Amiga rom?
I'm disassembling Amiga Kickstart 1.0 ROM (NTSC) and looking for the dos.library code. I'm sure dos.library is in the ROM since it's needed to use the disk drives. I also found this area: (Symbols ...
- 8,214
6 votes
1 answer
750 views
Did a combined RAM+ROM chip ever exist?
I'm primarily looking at the late 70s and early 80s where it seems like there would be a practical use for an IC that combined a traditional mask-ROM chip with a small amount of RAM. After all a ...
- 5,317
3 votes
2 answers
514 views
NES vs SMS ROM speed
The NES used a 6502-derived CPU at 1.79 MHz. The Sega Master System used a Z80 at 3.58 MHz. How did they differ in terms of what speed grade ROM they required in their respective cartridges? I know it'...
- 65.4k
9 votes
6 answers
5k views
Did ROM chips jump from 8K to 32K?
This is a question about mask ROM (not EPROM) chips of the 8-bit era. The size of DRAM chips increased by factors of 4, so there were 4kbit chips, then 16kbit, 64kbit, 256kbit etc. The natural width ...
- 65.4k
11 votes
2 answers
1k views
Where to obtain 3c509b empty boot ROM chip?
I'm planning to write iPXE to boot ROM of my 3c509b to enable HTTP booting on my old computer. What is the type of the ROM chip and where would you obtain it? It's 28 pin connector, please see picture ...
- 213
16 votes
4 answers
3k views
Did anybody use PCBs as macro-scale mask-ROMS?
Early on, even fairly small ROM's were quite useful. For example, you could fit a minimal upper-case only font for a terminal into something like 256 bytes. And that's a scale that a human could lay ...
- 2,437
35 votes
2 answers
9k views
Why did the Nintendo Game Boy Color make the name of any game to have a specific checksum?
Inside of the GBC's Cartridge header there is metadata for the game and the Nintendo logo. The program that runs on boot (the BIOS/Boot ROM) checks the checksum of the Nintendo logo, and always has, ...
- 523
1 vote
2 answers
282 views
Dump Mask ROM on MAB8421
I am trying to find a way to dump the rom contents of several MAB8421 microcontrollers. I know that on many 8048 MCUs, you can use the external access pin to dump the rom, but the 8421 doesn't have ...
- 11
12 votes
1 answer
948 views
Can you read the character definitions (font) in an Apple II using PEEK in Applesoft BASIC?
Can you read the character definitions (font) from ROM in an Apple II using PEEK in Applesoft BASIC? You can do this on some other computers e.g. Sinclair ZX81, Commodore 64, and Amstrad PC1512, but ...
- 505
7 votes
1 answer
2k 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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